The funny thing is, I use a Nitecore i8 at home. It's extremely simple, and I often charge my eneloops in it. But it auto-detects to my liking, and while it's a bit big and expensive, it was also a gift. It also charges slowly, but I care more about battery health than charge speed. The only step up that makes sense in my head currently is to the MC3000, because for the fun don't-actually-need-them features, that's the one that ticks the most boxes.
I do have a spare single-cell USB-powered charger, it is actually a SupFire AC-16, but I've only used it once. It actually currently lives at work. I have a cool tiny charger for my 10250s from CRX and my Klarus Mini One Ti charges its own 10180 cell. I can't remember for sure, but I might also have a charger that came with one of my ThorFire lights somewhere...
You need to make sure that if a shadow moves across the solar cell and voltage drops below the minimum spec the charger recovers gracefully and continues to charge —- rather than resetting to starting from scratch again. This has been a problem and caution I’ve seen brought up repeatedly with small chargers when people tried using solar cells with them.
But you just gave me an idea on the software side that would be extremely nice.
Why not make an emergency mode in which it turns off charging if the voltage drops between 4,5-10V, trying to consume as little power as possible just to keep itself on and preventing settings from changing?
Well, what I meant was that the hardware doesn’t have to crash or “reset” when a shadow looms overhead. It can be made to gracefully recover as if nothing happened. I don’t know if it needs software support for that or not. I assume not. But I’m not an EE.
https://www.aliexpress.com/item/32882318330.html?storeId=923042&spm=a2g1y.12024536.productList_2808692.subject_8
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The icharger 208b is relatively small in size with alot of power handling but the power supply to reach the capabilities of the charger takes almost twice the size of the charger.
Charging 4 li-ions at 3 amps each would need around 70 watts from the power supply. The max charge rate would all depend on how small and efficient you could make the power supply for it’s size.
If your trying to find out the discharge capacity and have it graphed like HKJ does, I don’t see why you need to do more than one cell at a time. To me seeing what one cell can do at 3 amps is more important than what 4 cells can do at .5 amps.
Doing 4 cells at a time would require 4 data logging graphs going at once which I guess is possible but the first link I posted would handle one battery at 3 amps, so for 4, you’ll need 4 of those or one 4 times the size.
And how much power are they discharging and how big is the load discharger.
If its going to be all in one unit a middle ground has to be meet somewhere, if not then bulkier additional devices could be added I guess.