I used this for charging a sla battery that keeps my Raspberry Pi weather station up and running.it really helps to have an electronics background and be familiar with how the chip that runs this thing works. If not, this may not be for you. The datasheet for the chip is available online.what I did was swap out the current sense resistor to 0.1 ohm which limited the current to 2A. Then I used a discharged battery to adjust the MPPT point to 18v which was the value for my solar panel. Then I used a fully charged battery to set the voltage to 14v which is kind of a midpoint voltage for an SLA battery that works for me. I also changed out the heat sink for a smaller one, then connected the top of the heatsink to a larger metal plate. The problem with the supplied heat sink is that protrusions from thru hole components are at risk of a short. In my mind this is a significant risk factor and one that has come up in other reviews.Because this ended up working out as well as it did it gets five stars from me !

Review date: 6-5-2024, Revision: B...They deleted my original review. This is another try...This is a DIY solar controller. It requires that you google, an alignment procedure that's, might be a bit too much for some to follow (you need to have, and know how to use, a volt and current meter - Your volt and current meter, needs to go up to at least, to your solar panels spec'd output). See below, "Required reading," for how to align the controller.I used mine on an OLD Sunsie SE-1800 (18W) solar panel, with new leads. This was without the in-line diode that were made by Sunsue, that I already had. My panel has an OP of 21v approx., and short circuit test op current of 0.44A (440mA), sitting outside, under full sun. Other spec's are, 1.2A at 15V (18W).Using this MPPT controller, I got 0.52A output, from inside my car (sitting on my dashboard, under full sun, through the cars windshield.). I use this set up to keep my cars battery charged, because the car sits a lot. And, I have HAM radio's pulling parasitic current, and I can't just disconnect the radios. My battery is an AGM. Its a Odyssey ODX-AGM34R (this is oversized for my car, because, HAM Radio).Bottom line after, misreading one sentence, I had to re do the set up, as described below (google, the above key words, or read below, "Required reading"), and now the controller seems to be working correctly. I'll keep checking on it..Required reading:Google : “robotzero.one 5a-mppt-charger-instructions”Below is the just of what the instructions say (it a copy)....Instructions for setting up the MPPT-V08A Lithium Solar Charge Controller with CN3722The information in the listings for these modules is virtually incomprehensible so after a bit of trial and error I’ve worked out how to set the maximum output current for your solar panel and the cut off voltage for your batteries. The instructions below are using the following items.Step 1First turn the voltage pot fully anti-clockwise and turn the MPPT pot fully clockwise. You will be able to hear them click when they are fully turned.Step 2Connect the solar panel but don’t connect the batteries.Connect a voltmeter across the battery terminals.Turn the MPPT pot anticlockwise until a voltage reading appears and the LED flashes blueStep 3Connect batteries that aren’t fully charged via an ammeter.Turn the voltage pot clockwise until a reading appears and the LED turns red.Step 4Adjust the MPPT pot to reach the highest value on the ammeter. This is the maximum charging current your solar panel can provide.Step 5Charge the batteries in a quality charger until they are full.Connect the charged batteries.Slowly turn the voltage pot anti-clockwise until the current shown on the ammeter is 0. This is the cut off for charging when the batteries are full IE the maximum charging voltage.AdviceNote that the above is just a tutorial for setting up these devices. Your finished system must include battery balancing so your batteries are evenly charged. Without a balancing system your maximum charging voltage could be unevenly distributed. For example if your maximum is set at 16.8 for 4 batteries you might expect them all to be topped up to 4.2v but without the BMS they are could have any value that adds up to 16.8v. Some of them could be overcharging.

Based on the website description, setting this device up for use sounded pretty simple. It is not. So be aware.

The guide in the description is easy to follow but the potentiometers don't click, so you have to spin them a lot and do some guess and checking. But I was able to get it to charge my 18v power tool battery with an old 100w solar panel. I made a video of this on Youtube @hackertwins idk if I can post links in a review

Unit arrived DOA, appears to be a heat sink short to some leads that were trimmed long. Also no instructions whatsoever. Popped heat sink off and the unit started working but rubs hot as one might expect.

You have to adjust the right voltage for the type of battery. Beside that it work ok.

This is a great little manual MPPT charger! I got it for a particular project needing to charge 12ah worth of LiFePo4 cells from a small solar panel. This is a manual MPPT, so when you adjust the set points, it's particular to the panel you tune it for.The output voltage is adjustable for any battery chemistry or direct use you need. Just follow the instructions someone else already posted to set the input current and output voltage

Great simple MPPT charge controller for small systems. I used this to build a 10w solar street lamp with a 19v NIMH battery pack and a 20w PV panel it works great. Adjustment via potentiometers. Simple.