Mixing Batteries With Different Ratings

battery
multirotor

#1

I’m upgrading from a quadcopter to a hexacopter which means my battery amp draw goes from 64 amps to 96.
The current battery I have is 5200mah with a 10c rating. (54 continuous amp draw. 20c (104amp max.) I know this is not ideal but it works fine. If I upgrade to 6 rotors I was thinking about getting this battery (https://hobbyking.com/en_us/turnigy-graphene-8000mah-4s-15c-w-xt60.html). It allows for 120 continuous amp draw. I don’t want to just put the old perfectly good battery on a shelf, if I put both batteries in series for a total of 13200mah, would that work even though the 5200mah battery only has a 10c rating? Would the 15c battery take most of the load off? The 8000mah new battery is 4s and 5200mah old battery is 3s.

Thanks


#2

Hi
Firstly you CANNOT put a 3S and a 4S in parallel,:scream: the terminal voltages are different and the 4S will try to charge the 3S with a high current which will destroy or worse the 3S
You can put batteries of the same S configuration in parallel with different C (discharge) ratings :slight_smile: and as you suspect at those times when your hex draws a high current (rapid climb etc.) the higher C rated battery will produce more power. I don’t see this as an issue at all
Hop this helps
Steve :slight_smile:


#3

Thanks Steve,

Would these two batteries work in series (Battery 1: Positive to drone, negative to Battery two’s Positive. Battery 2’s negative to drone.)

Multistar High Capacity 3S 5200mAh ( https://hobbyking.com/en_us/multistar-high-capacity-3s-5200mah-multi-rotor-lipo-pack.html )

Turnigy Graphene Professional 8000mAh 4S 15C ( https://hobbyking.com/en_us/turnigy-graphene-8000mah-4s-15c-w-xt60.html )

Thanks :slight_smile: @stevietee10


#4

Hi
This would give you a terminal voltage of 25.9v (nominal) and about 29.4v (fully charged) and the first thing to do is check your ESC’s and Motors can handle this power, which I doubt but not having knowledge of your set-up I should not comment any further on that :slight_smile:

On an electrical point of view, there is nothing to stop 3S and 4S being used in series. The big difference in C rating and capacity (mAh ratings) will cause an uneven discharge rate between the batteries which you would need handling.

FWIW my suggestion would be to get/use the Graphene 4S 8000mAh 15C (120A burst) on the hex (two of the same in parallel if you need more flight time) and use the 3S for something else.

Hope this helps
Steve :slight_smile: