Battery charging

Flashlight Modding and DIY Parts
1

Hello,

I’m building a battery pack using two 21700 Samsung 50E batteries connected in parralel.

I used some Aliexpress BMS that has common pads for charging and discharging.
It probably didn’t comunicate well with my charger.
I’m wondering is it safe to charge/discharge the mentioned pack using 4.2V 2A CC/CV charger.
I’m using Dualflex driver board from TaskLed for driving the LED-s.

I uploaded the photo of the charger in the post.

Screenshot_20260702_014029_com_alibaba_aliexpresshd_ProductDetailActivity
Screenshot_20260702_014029_com_alibaba_aliexpresshd_ProductDetailActivity1080×2388 242 KB

Screenshot_20260702_014514_com_alibaba_aliexpresshd_ProductDetailActivity
Screenshot_20260702_014514_com_alibaba_aliexpresshd_ProductDetailActivity1080×2388 279 KB

2

Parallel? Yeah, probably. If true cc/cv, yeah.

3

Any suggestions on which BMS to put or smth?

4

Not in the slightest. A bms is for series cells. You can parallel 100 cells and charge them directly as if charging 1 cell.

5

Typically you do not need bms for single cell charging, but for short circuit protection, or too much load you may want one, which one depends on range of current your project draws