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c4xp Youare my brother from another mother :) I had the exact same modifications done.

MrBungle 20/01/2019
This device works quite well at lower currents (< 3A). MPPT via panel voltage tracking seems to work quite well. I have mine outputting an almost consistant 10 Watts(2.8A @ 3.6v) into a 1s20p Lithium battery(nom. 3.6v, 45Ah) from a 12.5 Watt panel (21Voc, 17Vmp), so approx. 80% efficiency, even in 42 degree celcius ambient heat with panel temperature above 60 deg C !! (Australian summer). In 'cooler' summer weather (mid 20's) I get maybe an extra Watt out at mid day (~11W -ish). Although this is advertised as working up to 5A, even after extensive testing I was not able to get much above 4A with a 25Watt(measured) panel and very good heatsinking: I only get 15 Watts out (4.2A@3.6v) so efficiency at higher currents suffers badly (25W in, 15W out = ~60% efficiency) This item, as shipped, will NOT work with 1S lithium because the regulation voltage can only be adjusted down to ~6.5v, however, it is relatively easy to modify it for 1S operation. To do this, simply replace the 22k resistor (R7, marked 223, 0603 size) with something around 75k to 100k. I used an 82k resistor which alows me to adjust regulation from ~3.0v to ~9v. Note that the supplied heatsink itself is okay, but it is useless as supplied because it is mounted with a thick dob of silicone adhesive. This is because A) the current sense shunt resistor is thru-hole and protrudes, and B) the PCB tracks under it have exposed solder pads. Poor design/lack of forethought by whoever did the PCB layout!. Therefore, mounting the heatsink directly to the PCB would cause a short circuit. I have modified mine with heatsinks on the top side packages(Mosfets and Diodes), and also a heatsink with a drilled hole (to clear the shunt solder pad) un the underside using double-sided tape as insulation to avoid shorts with the board tracks. Not exactly ideal, but much better than as-supplied.
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