Hi, all!
I am doing embedded projects, and for that purpose, i bought 18650 LiPo cells (3400mAh ones, this vastly
beats the price/wh of the pouch cells i could find) with protection circuitery. To put it behind : these are not
something_fire fake/crap cells, but samsung ones; i also checked the capacity and it was accurate. So i have good quality cells, i have a balancing charger to balance them properly before doing packs, and i'm super cautious.
So here is the problem. I have those 3.4Ah cells, and i want to use multiple cells in parallel for increased capacity. I keep them in parallel to avoid the need of a BMS. Now, in my application, i don't want to extract the batteries to charge them. So i use a lipo charging circuit. At the moment an adafruit one that is great, but a bit expensive. The problem is that it can only provide up to 1 amp of charging current to the batteries. So with 4 batteries, i'm in for more than 13 hours.
Firthermore, i'd like my device to be able to work like a laptop : if i plug it to charge it, i can keep using it. So i need more current.
So what i want to do is to use multiple charging circuits in parallel to do that. The reasoning is that current will increase, and since the boards will all read the same tension from the batteries, they will have similar behaviours.
However, i am concerned by the fact that if a charger sends current while another reads, the reader will get a 4.2V tension and stop chargin. I don't think that it would matter at end of charge, if one charger stops slightly before another, but during the charge i fear that i may be problematic.
Do you think that i can use multiple lipo charge circuits in parallel to charge the batteries (each time, bellow 1C, even 1/3C) and thus increase the current or not?
Otherwise, i considered using a charger per battery/couple of batteries, then connect the positives poles of the batteries to a diode, then merging all + together after the diodes, so that the current couldn't flow from one charger to another. Is it a valid aproach?
So, if one would tell me if any of those two aproaches is valid or not, and if not why? By the way, if you want to bring precisions even if it is valid, feel free, i like reading and learning stuff
I tried searching on the web, but all i find is how to connect two lipo in parallel or in series.
Many thanks in advance!