5 items
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SMAKNSee Similar
SMAKN® 2 Wire Green Dc 4.0-30v LED Panel Digital Display Voltage Meter Voltmeter - SMAKN
DocoolerSee Similar
Docooler 10A 12V/24V Solar Charge Controller Solar Panel Battery Regulator Safe Protection - Docooler
ALLPOWERS™ New 18V 5W Portable Solar Car Boat Power Solar Panel Battery Charger Maintainer for Automobile Motorcycle Tractor Boat Batteries - ALLPOWERS
IOTA Engineering
IOTA Engineering IQ4 Smart Charger - IOTA Engineering
ALLPOWERS 18V 12V 7.5W Portable Solar Car Boat Power Sunpower Solar Panel Battery Charger Maintainer for Automobile Motorcycle Tractor Boat RV Batteries - ALLPOWERS

Side by Side Comparison of: SMAKN vs Docooler vs ALLPOWERS vs IOTA Engineering

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SMAKN http://ecx.images-amazon.com/images/I/411Y0nFyZyL._SL160_.jpg
SMAKN® 2 Wire Green Dc 4.0-30v LED Panel Digital Display Voltage Meter Voltmeter - SMAKN
Docooler http://ecx.images-amazon.com/images/I/51JeQtZ3RhL._SL160_.jpg
Docooler 10A 12V/24V Solar Charge Controller Solar Panel Battery Regulator Safe Protection - Docooler
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ALLPOWERS http://ecx.images-amazon.com/images/I/41BTp0SJbSL._SL160_.jpg
ALLPOWERS™ New 18V 5W Portable Solar Car Boat Power Solar Panel Battery Charger Maintainer for Automobile Motorcycle Tractor Boat Batteries - ALLPOWERS
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IOTA Engineering https://images-na.ssl-images-amazon.com/images/I/31szyzp723L._SL160_.jpg
IOTA Engineering IQ4 Smart Charger - IOTA Engineering
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ALLPOWERS https://images-na.ssl-images-amazon.com/images/I/41pTsIe9yFL._SL160_.jpg
ALLPOWERS 18V 12V 7.5W Portable Solar Car Boat Power Sunpower Solar Panel Battery Charger Maintainer for Automobile Motorcycle Tractor Boat RV Batteries - ALLPOWERS
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eComparisons ScoreThe "Comparison Score" Is calculated based on the average number of times this item was compared with other items in this category by our users
User Rating (Amazon)
User Rating (Amazon)

Five Star Reviews:

Great little voltage display
August 31, 2017
Great little voltage display, I made a little camper in my pick up and wanted a box to tell my solar charge state and mount a phone charger, this worked great with some basic parts from Home Depot.
Easy to use and clear to see
July 18, 2017
Easy to use and clear to see. Super fast installation. Used this to monitor a battery without always having to hookup my volt meter everytime.
Good value for a cheap and accurate voltage display
January 27, 2015
Bought this to monitor voltages on some of my RC video equipment. It's small, cheap, and accurate. Mine was accurate right out of the box (tested with a Greenlee DM-820a multimeter), so no further adjustment was necessary. The display is nice and bright, visible even in daylight. Can't ask for anything better for this application.

2 things to be aware of:
1) The plug on the back is a little loose - not the plug soldered onto the board, but the removable plug containing the voltage leads. I don't expect it to come apart while the display is mounted, but if you're not permanently mounting the display, you may want to reinforce the connection with some hot glue or similar non-conductive adhesive.
2) The clips on the side are positioned for this display to be mounted on a panel that is 3/16in or less. I mounted mine on a 1/4in plywood board and had to wedge it in there without the clips to hold it firmly. Seems to work just fine though.
Before I permanently mounted it to my chassis to measure ...
November 29, 2014
Before I permanently mounted it to my chassis to measure a 13V +/- 2V source, I connected it to my bench power supply and varied the voltage from about 3v to 20v. I cross checked its accuracy against my Fluke 87V, a more accurate and higher resolution meter. This SMAKN meter was about 0.5V off in the low voltage range, up to about 7-8V. However, beyond that range it seemed to track the Fluke quite well. It has a pot to calibrate it, but I didn't mess with it. Its default accuracy was OK for my use.

The green display is pleasant and large enough to read from several feet away.

Considering that it cost me just about $6 including Prime shipping, it wouldn't be fair for me to complain that it is not as accurate as a Fluke that costs a few hundred dollars. For $6, it is 5 stars!
SMAKN heck yeah! This unit is adjustable for accuracy.
May 2, 2014
Bought these to install in my 50/10/2 amp manual battery chargers. Just made keeping the batteries charged on 5 vehicles a whole lot easier. Now I don't have to drag a multimeter along with the charger.
I mounted the SMAKN ( love that name) volt meter on the front right below the original amp meter. Looks awesome, especially at night I can check where voltage is at a glance from afar.

Both SMAKN VMs I recieved were reading .1 V too high according to my expensive Greenlea multimeter which read 13.9 V. I noticed a variable resistor on the PCB marked "VR". It takes a small flat screwdriver such as for eyeglass repair to fit it. I turned it CCW just a few hairs and lost .3 V on the display so it doesn't take much to make a fine adjustment. Got both meters down to 13.9 from 14 and everything is peachy.

The hole required to panel mount these bad boys is 1-25/32" x 1"

I might buy more of these to put on my riding mowers just because they look so cool. The green LED would match the John Deere too!
gives the proper amount of overcharge protection to my battery and safely powers 12v load
August 27, 2017
I needed to wire up a solar panel to charge a 12v SLA battery that would power a security alarm system I installed on a cargo trailer. This product is easy to wire in and understand -- I didn't need the manual. All of the icons and LED indicators are perfect for what I needed. My solar panel outputs 18v on a bright, sunny day. So, this gives the proper amount of overcharge protection to my battery and safely powers my security alarm system.
More Than a Charge Controller! This is a Load Controller Too!
June 21, 2017
This little charge controller has already been through a tough North Dakota summer- and is still working great!I thought for sure I was going to have to build a weatherproof enclosure for this as the sides are open for ventilation. I figured dirt and rain would have this system of the fritz in just days. But since this was an experimental system for solar powered pumps, I figured I might as well sacrifice this inexpensive controller to see where the limits are.To my surprise, the system has been wet, dirty and shocked hard when the 2X4 it was attached to fell over in a rain\wind storm. So far, it still works perfectly. It appears there is some sort of coating on the circuit board that insulates it from the environment! Whoever built this understood it's a field unit and designed it accordingly.The screws on the base can be tightened very tight to hold wire connectors securely- without stripping or breaking the device. The screws are made from plated metals to prevent corrosion and the base where the screws attach to is metal too. No worries about breaking this device with field use when you really need to torque the wires down hard. This has hard metal where it counts!The unit comes with two open holes on the side for screwing it onto a piece of wood. (Or you could even tack it on with a nail.)The drawing for connections is universal and obvious. If you can put in a car battery, you can install this with a solar panel and batteries.As to it's ability, I paired this with two recycled 8AH 12V Sealed Lead Acid (SLA) batteries. It does a better job charging these than my expensive battery "conditioner" that's 20 times bigger and heavier than this controller.It's meant to be paired with a solar panel and if you are looking for its match in ruggedness and price, check out the ECO-WORTHY 20 Watts Epoxy Solar Panel I reviewed. I got really lucky and found two very inexpensive systems that were both ideal matches for my tough applications.If you are looking for systems to use outside in a garden or farm environment, I recommend these two systems!Put the Eco-Worthy 20 watt epoxy solar panel (crazy tough- I seriously abused mine and it looks brand new,) with this controller and keep any small scale battery array or starting batteries fully charge all the time. Auto-detects 24V and 12V battery arrays, measures their charge state and decides to charge them when their is excess power. It also supplies the load with the solar cell when their is excess power and it won't let the batteries discharge below a recommend state while powering the load! That means it powers the load from the batteries at night and will turn the load off once the batteries reach their discharge point. So this is much more than just a charge controller! It's a smart load controller too!!!!!Great for fountains, security\gate systems, outdoor video, cars\trucks\tractors\mowers\motorcycles\ski mobiles or any other vehicle that will sit a while and needs to have it's battery charged.My application is for a small 12V water pump in garden. (Think small waterfall pump.) 350mA continuous water pump 24X7. Still going strong after a months use!
Good device. Works as expected.
June 26, 2015
Great little controller for my project. I use this to maintain the voltage on a old truck battery. From there I run 6 4.2 inch computer fans to cool 3 grid-tie inverters on my solar panel arrays. It took about a week to bring the battery up to full charge and go into float charge mode.I run the fans off the "load" terminals, I would have preferred that the load output turned off when the sun no longer powered the charge controller but it provides power to the fans 24/7. It doesn't appear that there is an adjustment for the "load" output. In my case it doesn't matter, the 50 watt panel used with the charge controller keeps the battery up, I haven't seen it drop below 12.3 volts after running the fans all night.
Works as described. Just be smarter than the 1 star reviewers.
May 27, 2015
Seems to be working just fine. See people complaining about this killing batteries when still attached to battery and put into storage where there is no light. It does have 3 LED lights that will continuously stay on to indicate battery charge level.. Not sure if thats strong enough to nuke a large battery eventually but I suppose its possible. The smart thing to do, is add some male and female quick disconnect connectors in between all your wires so you can disconnect the battery from the Charge Controller when storing. You should always disconnect form this device when charging from a different source also. Just be smart and you wont have the problems you see on the 1 star reviews here.
Better than i expected, No micro board flaws. I think this will work well!
May 11, 2015
I did a bit of research on these, CMP12's (10amp), There are many verities, i figured i would get the newer one with the good heatsink good potentiometers and a crappy micro fuse, but i got a totally different one, with micro potentiometer, the upgraded heatsink, and the original auto breaker(instead of the fuse) SO I'M REALLY IMPRESSED!I will update after i hook my 80watt panel to this and run it over the next camping trip (probably get back to the review in june) If it turns out well i'll post pictures of mine without the case so you can see what i'm talking about.
Good value for controllers
July 1, 2014
I have 2 on my boat - one for the starter battery, one for the accessory power. Seems to do the job nicely - batteries are topped off during the week and ready for the weekend. Probably not as efficient as the MPPT type controllers, but in my case a few extra watts isn't a big issue.
Beach Bum and loving it
July 20, 2017
This product worked like a champ on the beach. We connected our inverter to a projector and watched movies on the beach during the night and in the morning the solar panel was pointed at the East and we were relaxing and drinking and enjoying the beach.In the evening the battery was ready and with no issues but to provide more power to the projector.
Does the job, so far! Read this, so you know what you're getting.
March 16, 2017
I was a bit skeptical of these after reading so other reviews, so I did a bit of testing. Hopefully my results will be helpful. My situation is that I am retired, have 2 vehicles and don't have a need to drive much. But it seemed like every time the weather turned bad, the 4WDs battery was dead, and every time it turned nice the rag-top was dead. Not only a pain to drag out a charger, but it's really bad for batteries to sit there dead. So I decided to get one of these and, if it worked out well, get a second so I didn't have to swap it between cars. After a couple months use and a bit of testing, here's what I can tell you:1) Don't expect this to charge a dead battery. Not designed to, and won't. What it will do is offset the natural loss in the battery and the minimal drain that the vehicle may have when off due to such things as the computer, security system, etc. There is an isolation diode contained within the solar panel to prevent back-feed drain regardless of whether the lighter or clip-on cable is used.2) The Red LED on the lighter plug is your friend, if you know how to use it. a) Connect lighter plug to solar panel, but do not plug into lighter socket. Aim panel towards sun and observe that LED lights, then aim away from sun and it goes out. This proves that the panel is generating electricity. b) Disconnect lighter plug from solar panel and plug into lighter socket, with ignition off. Verify that LED lights. This proves that socket is live with key off. c) Connect lighter cord to panel, and install panel either on the dash, windshield or (my preference) on the passenger's visor which can be rotated to catch the best sun based on how you park. Protect the panel from the elements; this is not an outdoor panel.3) Do NOT disconnect when driving, just rotate so it does not impede your visibility. The isolation diode will protect the panel and vehicle from each other regardless of whether the car is running or not. Frequently plugging and unplugging the lighter socket increases the chances of a bad connection inside the socket. If you must disconnect, do so at the panel end instead, and make sure the LED is on before reconnecting. If it ever seems as though it has failed, repeat the tests in step 2 above.If you do the above, I think you'll find this does what you need it to, and does it well. Hopefully this fills in the gaps in the manual, as well.
Works very well, keeps my vehicle battery maintained and ready to go
December 3, 2016
My vehicle battery kept going dead after the vehicle sat for a couple weeks, it being our spare vehicle at the time it was not very handy for it to not start on those mornings you needed to leave and your primary vehicle was not running properly etc.I purchased this charger and hooked the alligator clips directly to the battery, the cable is long enough you can then run it inside the vehicle and plug it into the solar panel and place it in the dash. I ran the wires discreetly to keep it all clean looking and you cannot see the panel on the dash while driving (every vehicle will be different). After 5 months we still have not went to use the vehicle and had a dead battery so it works very well. I will be purchasing more for my other vehicles that sometimes sit and various yard/farm equipment that sits.I am impressed with the ability such a little panel has.Please keep in mind this panel will not take the place of a malfunctioning alternator or a "bad: battery, but it will prolong the life your batteries. drained car batteries loose life quickly, not being deep cycle batteries these batteries are not made for multiple "cycles" of the charge on them .
simple, well thought out, good value
August 7, 2016
Obviously made in china, but I'm unusually impressed. Flaps that attach to suction cups have clothing snaps to tuck them neatly away and the power port plug (cigarette lighter plug) has a red light, which I quickly realized to be a great diagnostic tool.Plug the power port plug's pigtail into your vehicle without the solar panel while the key is out of your ignition. If it lights up, you have a live plug, not a switched plug. If it doesn't light up, you need to run a wire since power won't get to the battery otherwise. Also, when the pigtail is attached to the panel and not plugged in, you know if it's making power.I'll know in a month if this will keep my truck's battery from going flat.I really like the 2 pigtails they include, but it's wise to have a fuse between the panel and the battery, which is why back-feeding through a power port is preferable.
I would recommend this product to anyone that their vehicle sits more ...
March 19, 2016
I am a truck driver, and my car sits for several days at a time. With all the technologies installed in todays new cars, they cause massive drain on your batteries. The first time my car battery was drained and I had to have a service call to jump start my vehicle, as soon as I go home, I was online with Amazon to find a battery charger I could use to trickle charge my battery and keep the cranking power of the battery at the proper levels. It will not overcharge your battery. I would recommend this product to anyone that their vehicle sits more than 3 days before using. It is easy to install and use.
Worked great in place of a plug-in charger
May 18, 2015
This worked great. The motorcycle battery was dead, having been left unused for a solid year. I attached it in the late afternoon and it had enough juice to try to turn over the starter a few times, but the bike wouldn't start right away. I put it back on the next morning and the bike was running before noon. It was in full sun in the morning, and tilted up a bit to help with angle of exposure. This was exactly what I hoped this would provide and if you aren't in an all-fired hurry you could get by with one of these instead of a plug-in charger.
Great piece at a great price.
July 30, 2017
Love the idea not having to worry about the charging system and very easy to install.
Great product
June 2, 2017
Quick delivery and works with converter great
Works perfectly
April 5, 2017
Work just as planned in our travel trailer. Lots of money saving over the RV store.
Performs well and worth the purchase. Since I received ...
March 18, 2017
Performs well and worth the purchase.Since I received it, we've been at RV parks on shore power until 10 days ago. Since then this shows its stuff.What used to take a couple hours to charge the motor home house batteries, and then only to 12.6 VDC. With this plugged in, they charge in about half the time and up to 13.0 - 13.2 VDC that the deep-cycle batteries should be.
Nice addition to our iota DLS45 charger
January 31, 2015
Nice addition to our iota DLS45 charger. We live off grid and this speeds up the charging process of the battery bank when we run the generator. Much nicer than remembering to plug/unplug the manual jumper wire. 14.8v boost, 14.2v saturation, 13.6 float modes switch automatically with this item.
Simple and great IOTA addon.
November 15, 2013
Turning a 90 amp IOTA into a smart charger by simply plugging in the module is great! Be warned that if this unit is left plugged in and you don't install a blocking DIODE your battery system will lose charge over time due to the backflow of electricity. Simply plug the module into the port on your IOTA and let it start charging away.

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Four Star Reviews:

Good meter display for good price!
April 10, 2017
The display is brighter than you'd expect. The unit I received is very accurate for the price, within 0.1 volt of what my EXTECH multimeter reads.

Would like a trimpot for lowering the display brightness. If there is a trimpot for brightness then instructions or a label on the silkscreen showing it.
Simple, reasonably accurate, adjustable
August 3, 2015
This is a decent voltmeter. I am using it to monitor my motorcycle battery. I have it hooked up to a switch that also turns on other accessories on my motorcycle.

It's very simple to install, just splice some longer wire to your positive and negative contacts and it will run off of the power source. It does draw power so you need to install a switch or disconnect it when not in use. It was not accurate out of the box, but this was solved easily by the adjustment knob.

You may want to fill the connection point, or even the entire back end with hot glue to keep it waterproof and to ensure the connector does not rattle loose.

I had to send my original back for a replacement, but the replacement worked just fine.
Does the job
November 10, 2014
What a sweet little voltage reader. I put in a solar system on my Motor Home and need something to monitor the voltage -- the controler only has idiot lights, and while some see me as an idiot, I don't so I had to have something a real idiot could read. Hum, did I say that right? Anyway this works as it should and I can see battery condition at a glance. Cut a hole in a thin panel next to a cupboard, about eye level -- traced out and measured a couple of times to get it just right, cut the rectangular hole and pressed this little gem in for a perfect fit. No screws need, nice and clean.
Good little Meter
June 17, 2014
I havent installed it yet but i have tested it with a 9v battery and seems to work just fine. crisp display and seems well built.

Only down side is the shipping and handling is excessive, 5.99 for the product but then charged me $6.01 shipping. was mailed from IN to KY (neighbor state). Small light weight just in a bubble wrapped envelope. I also at the same time ordered a charge controller (much heavier then this meter) from another company on the same order which came from southern CA area and same bubble wrapped envelope (slightly larger size) and they only charged $2 shipping.

Pros: Product seems really good quality and arrived 2 days early then estimated.

Cons: Excessive shipping fees which i suspect so it can have a perceived cheaper price listing and just make up for it on the shipping fee as a marketing gimmick.
Quite nice, but needs some improvements
February 22, 2014
I bought two for monitoring my solar voltage coming straight down from the array. It proved to be quite accurate, fast, eye-catching display, and inexpensive. Here are my gripes though:

- The black and wires are way too small (think 6 strands of hair). I was able to splice enough wire off to extend the length with longer wire. I was able to solder and heat shrink over the wires...but, dang that was a PITA.

- I mounted it into a project box I got at RShack. I had to use a utility knife to cut a rectangle out to match the backside dimensions of the meter. That was, well, a PITA. It didn't fit perfectly in the rectangle cutout because this meter has 4 mounting clicky deals that stopped it from going all the way in. So, in order to secure it to the project box...I used Shoe Goo (rock hard rubber cement) and let it sit overnight. That worked great.

- Be careful with the wires and the little plug in connector. Do they make a connector plug with heavier wire? That would help.

-Needs a faceplate type mount with 4 screw holes.
Four Stars
July 14, 2017
Nice little controllers, but not adjustable in anyway
Almost perfect (I think)
June 24, 2016
This doesn't matter if you disconnect the charge controller after charging completes; but, either this model does not have a blocking diode or mine is broken, because my "conected" leds continue a weak glow after I disconnect the solar panel. I have ordered a second controller to test this problem; but, in any event, this is a great little package, especially the prong connectors and plastic shield cover. Those who complain about the "load" circuit not working probably do not know how load circuits work (only when there is no solar panel and/or when battery is fully charged). Check two controllers to verify before returning as defective. You need two for a backup anyway, so quitcherbit**in about buying a second one.
Great starting charger
February 29, 2016
I've had it for about 3 months and don't use it daily. I have mainly been using it with a 10 watt panel to charge my daughter's power wheel car. I did have to put a blocking diode in line from the panel as there was some current flowing back into the panel. I don't remember where I read thos information, but always make sure the solar panel is disconnected if there is no battery. If the panel is hooked up without a battery it can damage the controller.
Dead output in 7 days
February 10, 2016
Stopped working in 7 days. My project consist of a 12 volt 5 watts solar panel, a 12 volt 7 amp battery, a 12 volt to 5V/2A power supply and the Docooler Solar Charge Controller. The load output worked sometimes, when it did my battery gets a full charge during the day, and supply my power supply during the night. However the controller NEVER show all 3 LEDs indicating full battery ( I tested the battery using a volt meter). Now on the 7th day all 3 LEDs stopped working and 1 to 2 volts on the load output. I then tried using it as a 24 volt setup, I got a 24V load output but still no battery level indication.UPDATE: I received a faulty one so the seller sent me a replacement and now after almost a year the replacement stopped working. No voltage on the load output.The seller quickly send a replacement but took a while to arrive because it came from China. It is working perfect, I guess I just got a faulty one the first time, I will upgrade to a 20 amps soon. The red LEDs indicating how much charge the battery has are very bright but they don't bother me, they actually gets brighter (one by one gradually) as the battery receives charge, so I can say I can "see" my battery charging.
Great solar controller for my small project
May 30, 2014
I built a solar powered water pump for my water slide. I used a 12v pump, ATV 12 v battery, a solar panel I bought from Harbor Freight and this little controller. Seems to work great.
Works well for the price, but not perfect
May 28, 2014
My cheap-o 7A controller disintegrated over time, like it was made of paper, and I needed a heavier controller anyway for my additional panels.This one is doing it's job quite well, no reverse feed at night, very little loss from panels to batteries, and the addition of contacts for LOAD are really nice to have!So far, I have zero complaints after two months of use.EDIT - 4/14/2015:After using this charge controller for a year, it is still doing its job well, but not as well as it was last year. The output Voltage last year was 13.3V, and now it is pushing 12.8 on the average day. This is still sufficient to maintain a full-charge on a vehicle's battery, but not nearly enough to efficiently charge deep-cycle batteries in a solar bank. Dropping to 4-stars
Great trickle charge...
May 8, 2017
Usually after leaving the battery bank for two weeks or more, I come back and find them between 76%-81%. With this little trickle charger which Is in a port side window, the sun side of the sailboat, after two weeks came to sail and the battery bank was at 90%. It does what it says it will, I was very surprised because of it's small size and cost. Will see how well it does for a weekend trip.
I recently lost a perfectly good battery because I did not have a trickle charger ...
April 25, 2017
I have used these solar powered trickle chargers for many years. They keep getting lighter in weight and this product is very light weight. I recently lost a perfectly good battery because I did not have a trickle charger and hadn't started the vehicle for several months. I have had trickle chargers on a car that gets started maybe once or twice a year and the car still starts right up. It is the best way to keep your battery in good condition if you don't use the vehicle regularly. I also use it on my boat over the winter and the battery has never failed. The only drawback on this particular product is that the length of the cables with the alligator clips is shorter than others I have owned. It still fits on my Suburban but with only inches to spare. Otherwise I am very happy.
April 7, 2017
I didn't have an application for this solar panel at the time of purchase. I ordered this particular panel because of it's specifications and also price value. Upon receipt we inspected the panel for physical defects and found none. We then load tested the panel to verify advertised output and it performed flawlessly. My only comment would be that I wished it would have come with Siamese bullet style connectors like some of the other brands of 'DC' chargers and maintainers out there instead of the 'DC POWER ' style connectors which would have made it compatible with the others. Maybe ALLPOWER could manufacture a small adapter that would do that function I can never give a product a ' 5 STAR RATING' only because there is always room for improvement ; like in the example stated previously The power available LED on the cigarette lighter plug is a ' PLUS ' but could have been incorporated into the panel itself to verify it was producing power irregardless of output choice In closing I would like to commend ALLPOWER on a great product at a reasonable price. I would welcome similar products from this manufacturer.Thank you !!!
Trickle charger
January 30, 2017
This charger is primarily a battery maintainer. I tried starting my vehicle after two weeks. The battery had plenty of "juice" to start the vehicle. I had previously set the solar panel on my dash with cigarette charging cable attached. All charger equipment worked as designed.
Clip on to battery and stay charged. I purchased ...
December 2, 2016
Clip on to battery and stay charged. I purchased this product to keep my 06 Sportsman charged up between uses. My folks have had an atv for years (2000 Magnum) on the farm and after sitting from time to time the battery just couldn't maintain its charge, didn't want that to happen to mine. Have had the charger on for about a month now and electric start works every time.minus 1 star for the cheap fabric around the solar cells, wish it would have its own weather tight plastic case or thin aluminum box with window for the cells
I use this to keep my 8Ah fish finder battery ...
December 5, 2015
I use this to keep my 8Ah fish finder battery charged on extended bushwhacking camping trips. Fished 3-4 hours every day for a week a couple times and this summer and this kept it charged. I wired the leads to a 12V marine plug and installed the receptacle end in my kayak and wired it to the battery. Let's me charge with the panel or plug in my phone charger and charge the phone from the battery. I also installed a stern post light. Make sure you keep the polarity correct if you do this.
A small price to pay for the potential to (hopefully) dramatically extend house battery life.
October 17, 2017
Am grateful that this controller is available to turn my 2 stage converter/charger (IOTA DLS-45 M Series) into a smart 4 stage charger for such a reasonable price, and that simply plugs in and you are done. Being that the brainless converter/charger was installed on my RV when purchased, can't imagine why the smart option was not selected at the start for the small step in cost. I will look forward to an improved battery life, else I will update this review and rating.
Four Stars
October 17, 2016
I don't know how to know it's working. But I trust that it is.
Four Stars
February 3, 2016
Working very well
A necessary assessory.
January 20, 2014
This little unit does a very nice job at managing the charging rates for my MH house batteries, especially bringing equalization in to play. The difference is so significant that I am quite surprised it is not already built in to the IOTA charger.

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Three Star Reviews:

I was using this to monitor my batteries on an E-Bike . . . .
September 26, 2016
I was using this to monitor my batteries on an E-Bike. After several months, it got so I have to tap the screen to get all the segments to light up. No big deal, but I suppose that some day I will have to tear the panel apart and replace this item. I am thinking it's all the bumping and crashes that induced this problem, so I really don't blame the meter. I have three other digital meters that seem to have survived the same treatment, so it looks like by the luck of the draw I got one a bit more sensitive to being knocked around. Still, a good digital meter.
Nice, but not very heavy duty
December 26, 2015
I've gone through several of these in just a year. For the price they are great, but they aren't made to last very long if you run them 100% of the time. I've had them on my Camper Trailer battery so I know when to charge the battery, and the LED's burn out after a pretty short time.. 4 months? Not to mention the wires are REALLY thin gauge.
Seems OK, but
July 23, 2015
The unit is very tiny. I was surprised. Hopefully it displays the correct voltage.
Not bad, but not great either
July 2, 2015
The construction of this meter is not great. The PCB traces are on the top side of the board, so the connector has no mechanical support. The only thing holding it on is the adhesion of the traces to the board substrate. Which means that it's going to pull off with very minor stress. When mine failed, I just cut the connector off the wires and routed them around the side of the board, and through the holes from the bottom. This creates a much more mechanically sound connection. Really, there's no point in even having the connector there in the first place.

The nice part of this is that it includes a trimmer to calibrate the meter, and it already comes calibrated to a reasonable tolerance. As much as you can expect for three digits, anyway. There's a diode that protects from negative voltage reaching the chip, and if you pull that off, you separate the chip's power supply from the main sampling input. If you give it an external supply, you can measure down to 0 volts, and it has the added benefit of not loading down what you're trying to measure. Doing that, you can probably also measure higher than 30 volts, but I don't have a power supply that goes high enough to test it.

Apart from the connector pulling off, my only other complaint is that the display is WAY too bright. It seriously lights up a dark room. I could fix it by replacing the 6 SMD resistors, but it's really more trouble than it's worth.
Nice Meter, but wires and connector are very fragile
January 15, 2015
Very nice little meter. The one I received was accurate and the display was bright. The wires & power connector are very fragile, however. Make sure you mount it solidly with no stress or vibration on the wires. The power connector on mine broke loose from the circuit board. I only took two stars off for the meter breaking in less than one day, because I had not mounted it solidly yet.
Its ok
June 29, 2017
its ok, not sure if the performance is as good as it could be tho.
December 13, 2016
Can't give more than or less than 3. Light weight. Doesn't seem to be well made but I am just using it to try make an ammo box solar generator for 12v batteries.
Five Stars
July 12, 2016
Seems to be working good, have not touched it since I installed it a few months ago. Update It still charges the battery but the output to the device being powered has become very unreliable when dealing with higher amperage (5<) Had to hook the device I was powering directly to the battery. Seems to still be working fine with lower amperage electronic components.
you would think a Solar Charge Controller would have a ...
July 11, 2016
you would think a Solar Charge Controller would have a port for solar panel cables. But no you gat to cut them or make them. Come on guys get your head out of their!.And give this the right cable ports!
Pot Luck Product
July 3, 2016
40/60 chance that "Load" has any output. If you buy this one, make yourself a test rig with a battery, panel, and multi-meter (connect in that order) and check load before spending time wiring up your system. Had 3 of 5 units in 2016 returned. No hassle on returns. Eventually I just switched over to the 20A version (which to date has had no issues).
power hungry controller
January 3, 2015
we got this to use as a battery charge controller .but it eats more power then it allowed to be put in the battery ???i am using a 5 watt panel and a 10 watt panel in parallel and can just barely keep a little 12v 5ah battery alive ?i would only use this with a 100 watt panel and a deep cycle battery .
So id definitely recommend if you just want to keep your battery from ...
October 21, 2017
I have a bass boat and I bought 2 of these to keep my trolling motor batteries charged while my boat is in outdoor storage. My outdoor storage facility does not have power to plug normal chargers into. I take my boat out about once a month and I just took it out. They should change the name of these to "Battery Maintainers" not battery chargers cause I don't think it charges the batteries very much. I think these just keep the batteries from dying is about all. I figured theyd charge up the batteries if I didn't use the boat but once a month...I just took out the boat after 2 months of storage and my trolling motor lasted 2 hours before it was completely dead and when using a normal plug in charger they'll go 10+ hours and still have over 50% of the charge when coming home.So id definitely recommend if you just want to keep your battery from dying but if you want it to actually charge up a 12v battery I'd go with some of the ones I saw that were 100W.
Falls apart after normal light use in the sun
September 23, 2017
Fell apart from the heat, left all this small plastic fiber bits. But giving two stars because it does seem to charge, however i would still want them to use better materials.Update: The seller has contacted me and has assured me that this is a problem that they are trying to fix with the cloth, it seems to be related to the temperature. They have been courteous and prompt while trying to resolve my problem.I have upgraded the star review because of how concerned they are about my experience.
good luck to you
May 16, 2017
The charger itself seems to work okay. However, if your intention is to mount the solar panel on your deck to charge your ATV or lawnmower battery underneath the deck, good luck to you, because the cord from the panel to the clips is VERY SHORT. I had to find an alternate mounting area for the tiny cord to reach my Suzuki ATVs and Toro Zero-turn lawnmower.
hooked 2 to a Docooler 20A 12V/24V Solar Charge Controller ...
April 20, 2017
hooked 2 to a Docooler 20A 12V/24V Solar Charge Controller Solar Panel Battery Regulator Safe Protection They dont seem to add enough charge to the battery to keep the battery charged and power the LEDs on the regulator.
Not enough output
March 21, 2017
It doesn't keep the battery on our motorhome charged when parked for over one month.
Ok for very light duty applications.
November 30, 2016
Works ok I guess. It doesn't have enough output to keep the car like I hoped it would. I bought this to keep the battery topped up in the jeep I use for snow plowing. The jeep has an aftermarket alarm on it that constantly draws power. The alarm will draw the battery in less than a week. This solar panel just isn't big enough for the job.

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Two Star Reviews:

Two Stars
January 12, 2017
no good
February 22, 2016
Two stars, it works good but the back is wide open, needs to be closed off with plastic or something
It reads two tenths of a volt low and there ...
July 25, 2015
It reads two tenths of a volt low and there is no adjustment. Not accurate enough for what I need.
Nice Display, Short Lifespan
March 11, 2015
Easy-to-read display, and consumes very little power. I really liked it until it died after 30 hours of use.
Very very weakly built. Not for industrial use.
May 2, 2014
I like the display. I like the size. I like the low draw.

I don't like the weak wiring and circuit connections. I have two of these. It has a fatal flaw though. The plug on the back that is soldered into the board. The soldering is very weak & fragile. You can easily break it with light pressure. So if you buy it - keep it stationary. Don't expect to move it around much. Don't expect it hold up during difficult installations.

Wires need to be longer and bigger guage too.
docooler Solar Charge Controller quit working
February 18, 2017
The load end quit working less than a month after I started using it
very cheap
February 18, 2016
it is very easy to short circuit and when it does the entire thing sparks and black smoke comes out, other than that it's decent
Good for your first solar project, but all those lights are quite random (Updated)
January 6, 2016
Update, Jan '16: I briefly shorted the wires attached to the load on this unit and it no longer functions at all. I disassembled, expecting to see a fuse or something but nothing. My fault. Use a fuse, or be careful. Lowering rating to two stars.We were shipped a basically generic product - it says 'CE' and 'CMP12' - no Docooler branding like the image here. We attached a 22W solar panel and a 12V 7AH motorbike battery to it. The brand-new battery shows two lights (ie medium charge) and the 'charge' light comes on when it's sunny and goes off when it gets dark - looking good.The strange thing is that the 'load' light is always on, even though there's nothing attached to the load outputs. It will always be on as long as you have a battery attached. Basically this light has little meaning other than indicating that the unit itself is functioning, and/or acting as an extra battery light.While we were yet to attach a load to this unit the battery lights would go up to three almost as soon as the sun came out, then go back to two as soon as the sun went down. Attaching a 4W water pump would make the lights go down to two after 90 seconds. We just hoped the lights were unreliable, and that we didn't have a faulty battery.For the big test we disconnected the solar panel, attached the 4W water pump, and left it running until the next morning. After 20 hours we were surprised to see the pump was still running and there were still two battery lights! We calculated the 7AH battery should be just about finished after 20hrs at 4 watts, but no problem. Also, with no solar panel attached the 'charge' light would always be illuminated or half-illuminated.So those lights are quite random. Keep a solar panel connected the whole time, ignore the 'load' light, and use the battery lights as a very rough guide. Clearly it's charging the battery to its maximum capacity and keeping it in good condition.I'll give a generous three stars because it's basically 'okay' - even though I recommend you don't actually buy one of these - it's just a generic model and these are being sold under half-a-dozen brands including 'generic' - all cheaper than we paid for this, down to about six dollars.This model is fun to use, guides you in wiring up your first project, and I assume it does the intended job in keeping your battery in good condition.
buy a better one you will be glad you did
December 20, 2015
buy a better one you will be glad you did
Draws too much current for a Solar Charge Controller.
December 1, 2015
Draws too much current for a Solar Charge Controller. At 12VDC, I measured the current draw at almost 16mA. This may not sound like a lot, but over a 24 hr period, this will drain your battery by 384 mA-Hrs. Not good.
Its a cheap controller. Killed my battery in a year.
April 15, 2015
You get what you pay for. Its basically just a voltage on/off switch with a low voltage disconnect. Not PWM. It does not have common ground between all legs which is a pain if you want to measure PV and Bat voltage from the same ground plain. I gave it 4/5 stars because the price is cheap so performance is what I would expect.Update: After a year this thing fried my 7ah battery, likely overcharging it. I put the controller it on a meter and it would be at 14.4-14.6V continuously even after the battery was charged. Does not appear to have a float V mode on this thing. Full Bulk voltage all the time.
Only works when direct sunlight is available. If you ...
August 5, 2017
Only works when direct sunlight is available. If you plug it into a cigarette lighter outlet in your car and leave it on overnight, it will drain the battery. Therefore, it is not of any use as a trickle charger to maintain battery charge during long periods between driving the car.
The material around the cell just disintegrates with the sun
July 24, 2017
Meant to be on the sun to charge your battery, but the material around the cell just disintegrates with the sun. Had to throw it away. It did keep the battery charge for a longer time, but could not keep it to just leave the car parked for extended periods and we have to change the battery in the end.
Power Vampire
July 21, 2017
What a great idea. I'm retired so my car, 2005 Scion Xb, sits 3 or 4 days at a time without use so I got this. Plugged it into the socket, got the bright red light, but the radio started playing. Weird right. So figured I would use it but just always remember to turn off the radio when I turned off the ignition. Twice in the last week I've had to have a jump to get my car started. Still a bright red light coming from this power vampire. I've had it past the time to send it back and get a refund so I'm out the bucks on this one.
Not enough power to keep up with an automotive security system!
April 16, 2017
Do not order this solar charger if you need one to maintain an automotive battery on a later model car or truck that has a security system. It simply does not generate enough power to keep up with the parasitic draw on the vehicles battery due to the security system. I tried using this on a bone stock 1998 Honda accord with a fully charged AGM battery. The charger was plugged into a 12Volt power outlet that is active when the key is off. The car sat for two weeks without being driven with the charger plugged in. Needless to say, the battery was dead when I tried to start the car. Very disappointed!
The battery worked fine and had no problems
March 9, 2017
This thing did not work and completely ruined my year old optima battery.The battery worked fine and had no problems.I used this thing because I dont drive my truck often. The truck still would die after a few weeks of not using it (my alarm system drains the battery)After a month or so the optima would only charge up to about 10% (Per autozones charging methods)
April 20, 2016
Per my measurements, this puts out about 160mA in direct sunlight in Florida. Voltage is right at 18v. Anything less than direct, bright sunlight and amperage drops down to ~40 - 60mA. Tested this using the cigarette lighter plug and with the alligator clips. I was thinking about permanently mounting this in my truck since it doesn't get driven much, but I'm not confident this will do an adequate job of keeping the battery charged, unless the truck is constantly moved so the panel gets direct sunlight.Also, like other have mentioned, the LED in the cigarette lighter pulls power from the plug itself. So if you leave it plugged in overnight, it will actually DRAIN your battery.
Great if you don't need 15v to equalize you batteries.
October 12, 2016
I discovered that you can not crank the IOTA chargers up to the voltage recommendedby my battery manufacturer for an equalizing charge.Both this and the charger also came with zero directions.

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One Star Reviews:

September 7, 2015
Bought two.- one failed after 6 minutes second after 22 minutes. Waste of time.
Four Stars
March 10, 2015
bought in 2014. just installed. worked 4 days before display segments failed. maybe it died in the box.
Didn't work.
January 24, 2015
After asking the question, will this work for a vehicle charging system and receiving verification that it would I tested the meter. Wired it all up, sadly as soon at I powered my car on the unit started to get hot and the tiny wires melted through their insulation. I'm not sure if it was a bad unit or if they just can't handle the power.
Labeled Wrong @ manuf.
July 29, 2014
Ordered DC 4 to 30 volt. Will not measure above 20.5 volts. Marked 4 to 30 on end, but 0 to 19 on the side. I used an adjustable DC voltage source and all of the meters were ok at 20 v but failed to measure above 20.5 v
Failure in minutes
June 20, 2014
2 out of the 3 items still work-- the Voltage Meter failed in about 1 hour.-- doesn't work any more.--
I purchased two of Docooler 10a 12/24v Solar Charge controller ...
September 12, 2017
I purchased two of Docooler 10a 12/24v Solar Charge controller and they do not control the solar panel charge at all. Fried my deep cell lead acid battery. Voltage in from solar panel to controller measured with meter was 19.5 volts, voltage out from controller to battery 19.5 volts on both units. Confirmed voltage meter accuracy with 12 volt battery.
September 12, 2017
Had my solar panel battery and pond pump hooked up lasted 2 weeks before it burned out crap product
August 7, 2017
Finally got around to installing this year. Unit worked for about 4 months and then just completely crapped out. First it stopped giving power to the load terminals (batteries were full).... and then it just completely stopped working period.
Draws more battery than a quality 10W panel creates
May 9, 2017
I had this hooked up to my camper in storage. Panel got direct sun about 85% of the day and indirect the rest. The panel is a quality 10W panel from an industrial source. Either the controller wastes too much current, doesn't prevent backflow, or both. Regardless my two 120AH camper batteries were drained from 13.5V when I parked the camper to 11.5V over a few weeks time. The goal of this unit was to keep the batteries topped off while in storage. Clearly a failure.
Find something else, spend more money and make sure you buy from someone who ships from the US, not China,
June 3, 2016
Terrible quality, will not last too long and definitely not very well seal to make it waterproof. When contacting the seller they don't have enough English to help you well neither they understand the way customer service is done in the US. Believe me you don't want to buy from this seller.
Got a defective one, returned for refund.
November 22, 2014
Defective, had to return. It would take voltage from the solar panel and charge the batteries but it wouldn't output any voltage on the LOAD terminals. One of the battery power level LED was defective (lit, off, lit), it has 3 red LED to indicate battery level.I returned it and purchased 2 of the 20A version and they both work as it should. Glad I did since the 20A version was about the same price as the 10A version.
Did not at all meet my expectations.
September 22, 2017
I bought one of these, tried it for a couple of weeks, and the voltage on my car battery, which was unused otherwise, actually decreased. I’ve an older car that, as long as I haven’t left a door ajar, doesn’t seem to lose any noticeable power when it sits. I thought this would be enough to offset occasionally opening it up and checking on a few things when it isn’t being used, but it just isn’t. Output voltage was close enough to the 18v, but it just doesn’t put out enough power. The position was good too. My car is facing south and almost completely unobstructed, so putting the panel on the dash was pretty much the ideal spot.At least the return process was quick and painless.For reference, it’s a mid-sized car that doesn’t take a ton of juice, a 2000 Subaru Outback.
Would NOT recommend.
March 30, 2017
ALLPOWERS 18V 5W Portable Solar Car Battery Charger Bundle with Cigarette Lighter Plug, Battery Charging Clip Line, Suction Cups & ManualWas hoping and praying this would be the answer. ...BUT...Doesn't work car is as dead as a door nail.!!!! Would NOT recommend.
didn't charge for me at all like it says
March 24, 2017
No Bueno.....didn't charge for me at all like it says.....and I live in Phx AZ....lots of sunshine here.
It Might Charge a Hotwheels
June 12, 2016
Waste of money. Wire to the charging connection are thin as threads. No noticeable effect on battery.
Light on the unit does not light checked the fuse my be I just got a bad one.
November 24, 2015
Unfortunately it does not work at all. Keep it plugged in and it would not keep battery charged. Light on the unit does not light checked the fuse my be I just got a bad one.
is fine, but there is not a big difference with ...
October 7, 2015
is fine, but there is not a big difference with the panel or without for my 27 marine Battery (trolling motor).
Mine a Dud?
May 10, 2014
I hate to denigrate a product everyone likes so well, but I'm not happy. I bought this when I bought a new battery, to protect an expensive investment in my motor home. It sits much of the time plugged in with little draw down, so over charging is an issue. But, rather than controlling the charge, the Iota seems to just block it. Even running the generator. Everything works off the generator, truck alternator, or house supply, but coach battery won't charge. After taking it back off, the battery charges, but doesn't hold it long, without use. Hope I didn't damage it with a misguided attempt so protect it.

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Pricing info
Old Price
Old Price
$6.99updated: Jan 22, 2019
$9.99updated: Jan 23, 2019
$22.99updated: Jan 23, 2019
$18.95updated: Jan 23, 2019
$24.99updated: Jan 23, 2019
Article Number
Article Number
IOTA Engineering
51.2 in
70.9 in
51.2 in
29.5 in
63.0 in
271.7 in
173.2 in
531.5 in
236.2 in
563.0 in
IOTA Engineering
Product Group
Product Group
Home Improvement
Lawn & Patio
Automotive Parts and Accessories
Automotive Parts and Accessories
Automotive Parts and Accessories
Product Type
Product Type
IOTA Engineering
IOTA Engineering
0.2 oz
1.2 oz
2.6 oz
0.1 oz
0.2 oz
149.6 in
157.5 in
212.6 in
157.5 in
236.2 in

Measure voltage: DC 3.3-30V (two wires Access)

Measurement precision:0.01V(3-10V); 0.1V (10-30V)

Display: Three 0.56

Display color: Green

Operating temperature: -10°c to 65°c

Automatically manage the working of solar panel and battery in solar system.

Overloading & short-circuit protection.Reverse discharging & reverse-polarity protection.

Under-voltage and over-charging protection.

Protection from lightning strike.Prolong the battery life cycle and keep the load work well.

Easy to set up and operate.Suitable for small solar energy system.

ALLPOWERS Car battery maintainer can charge 12V batteries with the power of the sun and create 5 watts of energy

Mono-crystalline silicon panel works in all daylight conditions and is weatherproof for added durability

Works with automobile, motorcycle, tractor, boat batteries and more

Built-in blocking diode to prevent reverse discharge

Package: ALLPOWERS car battery charger, cigarette lighter plug, clip line, clip line, Manual



ALLPOWERS sunpower car battery maintainer can charge 12V batteries with the power of the sun and create 7.5 watts of energy

Sunpower solar panel works in all daylight conditions and is water resistant for added durability

Works with automobile, motorcycle, tractor, boat batteries and more ( ★ below 18V device )

Built-in blocking diode to prevent reverse discharge

Package: ALLPOWERS car battery charger, cigarette lighter plug, clip line, suction cupds, instruction manual, 18-month warranty and friendly customer service

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