Two lithium chargers in parallel

GijsW

1 mW
Joined
Jun 5, 2020
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13
Hi everyone,

Does anyone know whether or not it's possible to charge a single lithium (LiFePo4 in my case) with two parallel chargers?
The reason I'd like to do this, is that for my application (an electric boat) sometimes I'm constrained by a 6A circuit breaker, while other times I could go up to 16A (depending on where I charge).
So I figured maybe I can put two (in my case 10A 87.6V) chargers in parallel, and just turn on one when I'm on a 6A outlet, and two on a 16A outlet. An additional advantage would be redundancy (one charger fails, I'm not stranded).

I tried searching on this forum/google but couldn't find a satisfactory answer, so it would be great if one of you guys could help me.
Maybe added diodes will help?
 
It depends on the charger design. Some don't parallel well because they check the voltage of the pack before they turn on, and may check during charge (by turning off output momentarily). If they do this and detect a higher voltage than what they expect (like from the other charger) they may not turn their output (back) on, and so it would only charge via one charger. This type of charger (and some others) also wont' work if you use diodes to isolate them from each other, because it also isolates them from the pack, so they can't check pack voltage to know if they should turn on or off, etc. There's usually no way to know if this is going to happen without testing the specific chargers in the specific situation. Mostly I expect the average ebiek charger probably works ok this way, but no direct experience with it.

There are some types (the "dumbest" ones) that work easily when paralleled, especially stuff like LED PSUs (Meanwell HLG or ELG series, for instance), because they simply always output whatever voltage they are set to (or designed for), regardless of what they're connected to, and just limit current to whatever they're set to (or designed for). But these don't have a shutoff for when the pack is full, so unless you manually check this during charge, they'll continue to trickle charge the pack "forever" (which may or may not be a problem, depending on the pack and the voltage the chargers go to, etc). So far this is the only method I've used for paralleling chargers; it does work.

Another solution is to use a charger that has programmable / selectable modes, so you can use a "fast charging" profile when you have more power available, and a "slow charging" profile when you don't.
 
Your comments were very helpful, thanks!

I found a vendor on alibaba (Sichuan Lingxiang Technology) who can supply me with 2 chargers which I can parallel when using a simple combining circuit supplied by them.

Thanks again!
 
You have a link for this charger and let us know how it works out the last charger I bought blew up the second time I plugged it in I got my money back you have to wait a month
 
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