ORIGINAL: ImpalaPolicePack
im charging 5s and 6s 5000mah packs at 7amps. i know its not 1c but i dont care if the packs does not last as long since they are cheap to buy.
i tought that i was only pulling 7amps, why is it more because of a 5s pack ?
anyway, like you said, the ps should handle it...
Ready for a bit of math?
Charging a 5s pack at 7A requires up to 147w of power (4.2v/cell * 5cells * 7amps). Since the charger is not 100% efficient (typically around 80%), add in another 20% of power for 176.4w. That is the power the charger will pull from the power supply. Since the PS outputs 12v, the power supply will need to supply 14.7A (176.4w/12v).
Charging a 6s pack at 7A requires up to 176.4w of power (4.2v/cell * 6cells * 7amps). Again, to account for efficiency losses, add in another 20% for 211.68w. At 12v PS output, it has to supply 17.64A of current.
I say "up to X watts" because the most power a charger will have to output is
just before the battery reaches 4.2v per cell and so is still in the CC phase of the charge. Before and after that point, the actual power required is a little less, but we always want to use worst-case to figure things like this.