Designing a multi-cell Lithium-Ion charging board or (small cc/cv buck or boost)

Thread Starter


Joined Feb 1, 2019
Hey guys,

I'm a big lithium battery nerd! I've built tons of battery packs from all sorts of different lithium chemistry's and cell types. From 2000mah/2ah single cell, upto 5kWH 16s batteries.

The problem I've been running into is on the smaller end.
You have:

* TP5046 boards for single cell charging with and without built-in charge and discharge protection.

* TP5100 boards, same as above but for 2cell/2s batteries...

But that's about it...

my main question is-

I guess without it being complicated sounding I need a way to make a tiny CC/CV buck/boost converter. I wouldn't rather use Fix-It valued resistors instead of trim pots which would also reduce the size... most switching Regulators I can find are either really expensive or they're discontinued and for the multi-cell battery charging IC's are normally really expensive to just buy 10 of them...


does anyone know of a relatively cheap IC that is capable of charging multiple cells in series that I could create a PCB for relatively cheap and small, that isn't overly complex. I don't mind having to use a separate Buck or boost converter since these boards are easily obtainable and are very small. I just need a way of charging multiple cells in series that will fit into all sorts of DIY projects. And it doesn't necessarily have to have built-in balancing either I can put a BMS on the battery pack itself..

Whole story...

there are tons of cheap single cell and multiple cell BMS protection boards. I just don't understand why they do not make a multi-cell BMS board with on-board charging using a buck or boost circuit. Or at least multi cell charging modules like the ones I mentioned above. That can be connected to a battery pack which has a BMS already.

normally I have to use a CC/CV Boost or Buck converter in order to charge any small battery packs over 2s. And this is inconvenient since most of these buck and boost converters are relatively large and will not fit inside of most projects like the TP5046 etc..

I recently just came across something very similar on eBay that claims to be a 1s, 2's, 3s charging module. Using some IC and a buck converter. And depending on which pads you short out will tell it how many cells are connected. As soon as I seen it I placed an order for 1 and hoping when I get it, the IC markings are readable. It's the only multi-cell up to three cells charging module I have ever came across. Picture below (any ideas what IC its using?)


Joined Nov 6, 2012
What do you intend to use for Input Power ??
Why does it need to be a SMPS ??
How much Charging Current do you want ??