Quote:
Originally Posted by mk351e
well, I gotta admit, I'm kinda crappin' my pants now, as it seems that I've REALLY missed the boat on chargers here!! It seems like these PS's are BIG, HEAVY, expensive, or cheap and extra work (CPU PS). Sooo,
1)how do you figure out what size power supply you need for your charger? Hyperion 610 - I know I need a 12VDC unit, but how many amps?
2) how do you figure out charge time on a 6S 5000mah pack? Ie, how is it calculated?
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If you want to know you can maximize the chargers capabilities (250W) then you would need something capable of at least 20A constant(250W/12V=20.8A).
As I mentioned, my PS (CPU PS from ebay) claims to be 30A (360W), but was getting a little overworked after running at 150W for to long, although in hindsight it might have been that the outlet or circuit in the house was being overworked (was plugged into my TV’s surge protector with the TV and DVR on).
But to directly answer your question:
if 1S = 4.2V at fully charged voltage
and you have 6S or 25.2V
charging at 1C (for 5000mAh 1C=5A)
So 25.2V*5A=126W <--minimum continuous watts
126W/12V (PS input voltage)=10.5A
So you need at minimum a PS that can handle 10.5A continuous (plus whatever power the charger itself will draw).
Depending on what type of charger you buy you might be able to get a 15A (if it is rated for 15A continuous) or you might need a 20A (if it is rated at peak).
As for charge time:
As long as you can provide you charger at least 126W of energy (as we just went over that is 10.5A @12V) then you can charge at a 1C rating, at 1C rating you can charge you battery in around an hour (shorter if the battery isn't at LCV, longer if it is out of balance. But it should be around 1 hour +/- 15 minutes for almost all charging situations.