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HomeRC & PowerAircraftHelicopterRadio - Servo - Gyro - Gov - Batt › Battery info - Parallel vs large battery
09-21-2013 09:34 PM  5 years agoPost 1
flyrchelis

rrApprentice

La Quinta, Ca

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Looking for some input re batteries. I have built an Octo Copter. I have 2 5000 65-130 C Batteries I put in parallel. After 5 minutes of flying as a test one battery took 3273mah and the other took 735mah. Is it normal for them to not go down evenly. I'm trying to figure out if I'm better off to run 2 in parallel or get one large battery. I have found a 10,000 mah battery at 25C continuous. I'm running 8 Avroto motors and they say the max power at 14.8 volts is 390 watts. So I figure that is about 9.3 amps per motor or almost 75 amps.

Thanks
Rich

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09-21-2013 10:31 PM  5 years agoPost 2
Dr.Ben

rrMaster

Richmond, VA, USA

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Something is wrong. The packs should not discharge with that great an asymmetry. Are the packs the same age and health with similar IR's?

Nothing wrong with a single higher capacity pack other than have a greater investment in a single pack if something were go wrong with that one pack.

Ben Minor

Peak Aircraft/Team Minicopter Team Futaba Team Kontronik USA

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09-21-2013 11:05 PM  5 years agoPost 3
flyrchelis

rrApprentice

La Quinta, Ca

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One of the packs is swollen at bit and the other is not. I didn't measure the IR.

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09-21-2013 11:24 PM  5 years agoPost 4
flyrchelis

rrApprentice

La Quinta, Ca

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Dr. Ben....

Looking at the spec's above what is the lowest C rating that I could get away with.

Thanks

Rich

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09-23-2013 03:25 PM  5 years agoPost 5
dkshema

rrMaster

Cedar Rapids, IA

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One of the packs is swollen at bit and the other is not. I didn't measure the IR.
It is not easy to measure the internal impedance of a battery. Some chargers will do it for the pack as a whole, or for the individual cells making up the pack.

On the other hand, one pack being swollen, and the other not -- you either have a bad mismatch between the packs, or one is very old, one is relatively new. Are they both the same pack, same age, same C rating?

-----

A 5000 mah pack with a 65C rating, is good for 325 amps. You should not be pulling the max current on a continuous basis.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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09-23-2013 05:33 PM  5 years agoPost 6
qraptor

rrApprentice

Illinois

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I didn't measure the IR
If your charger can do it, measuring the IR is probably the best way for you to know when the pack, or if possible, the individual cell is going bad.

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