Ever want a seriously powerful PCB for charging a Li-Ion pack? Whatever you want it for, [Redherring32] has got it — it’s a board bearing the TPS25750D and BQ25713 chips, that lets you push up to 100 W into your 1S Li-Ion pack through the magic of USB Power Delivery (USB-PD).
Why do you need so much power? Well, when you put together a large amount of Li-Ion cells, this is how you charge it all at once – an average laptop might charge the internal battery at 30 W, and it’s not uncommon for laptop batteries to be dwarfed by hackers’-built packs.
A 4-layer creation peppered with vias, this board’s a hefty one — it’s not often that you see a Li-Ion charger designed to push as much current as possible into a cell, and the chips are smart enough for that. As far as the onboard chips’ capabilities go, the board could handle pack configurations from 1S to 4S, and even act as a USB-PD source — check the IC configuration before you expect to use it for any specific purpose.
Want a simpler charger, even if it’s less powerful? Remember, you can use PPS-capable PD chargers for topping up Li-Ion packs, with barely any extra hardware required.
Off topic, but still. Remember to work as close to your operational voltage as possible. Yes you can step-up/down anything to anything but voltage conversion ratios exist and you’re not getting any younger, so why complicate things?
I recently made a flashlight from a single 3.7V 18650 and tried to drive a 20W 12V LED. Everything on the circuit was getting HOT! Then I put another 18650 in series, and increased the voltage to 7.2V. The heating disappeared, in fact I was barely able to feel it.