Can the battery be charged and discharged at the same time?

[maxchao]

I have an Align 3CX all in one charger, and yes this charger needs a fan to run it without overheating it. I stick a fan on the back and soldered a Dean’s connector to it, and yes I gotta have an power source for the fan. I don’t wanna mess things around in the charger and I don’t want to use two wall outlets when I’m charging. So here is my question:
Can I charge the battery and use the charging battery to run the external fan?
The fan is rated at 12V and 0.07A which is really small compare to the charging system, but I don’t know if have the battery charged and discharged at the same time would harm it.
The battery is 2100mah 3S, or sometimes 1320 3S
Thanks!

Josh

[jrohland]

I suggest you not do this. A LiPo charger has to be able to read the voltage from the pack as it charges. What you are thinking of doing will change the readings the charger is getting from the pack.

Because the charger will actually be running the fan, it might believe the pack is not getting charged. The charger will keep pushing more power back into the pack even if the pack is full.

While you may only cause the charger to never shut off the charge, I would be concerned about the pack getting overcharged. An overcharged LiPo can catch fire.

To answer your question can a pack can be charged and discharged at the same time. The answer is yes, sort-of. You see a balancer works by discharging individual cells in the pack when the cell or cells have greater voltage than other cells in the pack. Of course, this discharge is done with some intelligence.

I don't have an answer to how you should run the fan. However, I would not do it the way you are thinking of.

jrohland

[maxchao]

Ah! That makes sense, I'm glad I have not try it yet. while these charger are all trying to put as much as mah into the battery as possible, a little more might be bad for the battery. I will try to find some other source then. Like power the fan from inside, I'm still trying to find which point to solder to.
but Thanks jrohland!

Josh