This is just a 5 AMP rated Dc to Dc step down/buck converter. One Can get a half dozen for 10 bucks or so
I have a set of beard trimmers, now powered with a single 2012 era AA Eneloop after original battery failed.
The original wall wart powersupply/charger did not get packed in a recent move, so i found a barrell connector which fit, soldered it to bucker’s output, set it to 1.62v from a 12vdc source, and no green charging light on trimmer, no measurable current flowing. drat.
Raise voltage potentiometer, and green light comes on. yeehaw.
Dial voltage up until I see 0.18amps flowing, and then check every so often, for warmth, terminate when I do many hours later. Bucker Voltage was, and is, set to 2.32v, and it works well.
I just set the timer on my smart phone for 4 hours , unplug bucker, check battery voltage, if below 1.42, restart, set timer for an hour, lather rinse repeat till warm, or battery voltage rests at ~1.38v or above.
This bucker is just a single potentiometer for voltage adjustment. but there are dual pot versions for amperage limiting.
Enter a 3s 18650 holder. Set my non current limiting 100 amp power supply to 12.55v, hook up pack measuring 9.23v and the pack is accepting 10+ amps.
Dial voltage way down until it is about 2 amps, comeback a bit later to find well below 0.5 amps, bump up voltage more until 2 amps is flowing, again, until 2 amps or 12.55 v is reached.
Not wanting to babysit the voltage potentiometer, i think of my XL4005 bucker which does have current control.
Wire it up, set it to 12.5v, without pack connected, then connect discharged pack and dial current potentiometer to allow no more than 1.4 amps.
Heck, I got 10 hours to recharge, lower current to 0.2 amps. walk away. check every so often, watch voltage slowly rise toward 12.5v, and when it does, watch amps taper.
I know I should terminate when it accepts ~ 0.1 amps or less, but often come back to see 0.00 amps, but could be 0.04 as my wattmeter is not high precision below that.
Pack voltage is in the 12.45v range when I do remove charger/bucker. Each cell is within 0.04 of each other. I can and do charge them individually when they drift apart after many cycles or high charge/discharge currents reveal the resistance on the inter connects.
How important it it to terminate charge current at 0.1 amps, when each cell is charged near, but under, the 4.2v max?
These are matched cells from an old 1.5ah 18v Ryobi battery
