Mixing different MA size in Series - RC Groups
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Nov 09, 2017, 05:16 PM
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kell490's Avatar
Discussion

Mixing different MA size in Series


I need 8S power for my EDF I have an issue with one cell of my 6S Hyperion G7.
Original battery configuration

Hyperion G7 HVLI 6S in series with G7 HVLI 2S both 5200MA 90C Burst 45C continues Charged to 4.35 per cell

I want exchange it for a Revo so I can fly this weekend until I get the Hyperion sorted out.

New setup will be
Revo 6S 4400 MA 4.20 Blend 70C Continues 140C burst with Hyperion 2S 5200MA in series Revo charged to 4.2V Hyperion 2S charged to 4.35V since it's a HV the revo is not ill lose a few volts and some time due to 800MA loss of capacity ill gain in lighter battery. I think it will work fine I don't think capacity really makes much difference other then run time since it's in series still have more then enough power. Wanted to get some feedback on this before I try it.

Hyperion 6S HV + 2S HV = 34.8V

Revo 6S 4.2V + 2S Hyperion 4.35V = 33.4
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Nov 09, 2017, 06:05 PM
Bombs away! Err...landing
Ira NZ's Avatar
Basically, never mix different MAH capacity cells in series. You'll risk overdischarging or over charging the lower capacity ones and destroying them or blowing them up.
Nov 09, 2017, 06:08 PM
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Nope. Do not do it.
Nov 09, 2017, 07:51 PM
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kell490's Avatar
Quote:
Originally Posted by Ira NZ
Basically, never mix different MAH capacity cells in series. You'll risk overdischarging or over charging the lower capacity ones and destroying them or blowing them up.
How would I over charge one I don't charge them while they are plugged together in series I'm charging the batteries separate then I have a Y cable which puts them in series when I put them in the Jet. I figure the only issue is my discharge time will be based on the lower 4400MA battery cutting down flying time Ill have to watch the voltage so I don't over discharge the smaller 4400MA battery.
Nov 09, 2017, 08:03 PM
Registered User
Quote:
Originally Posted by kell490
How would I over charge one I don't charge them while they are plugged together in series I'm charging the batteries separate then I have a Y cable which puts them in series when I put them in the Jet. I figure the only issue is my discharge time will be based on the lower 4400MA battery cutting down flying time Ill have to watch the voltage so I don't over discharge the smaller 4400MA battery.
You are correct, charging is not an issue if charging separately. As far as discharging, one of my packs I use for EDF I run a 5S 4000mah and 3S 5000mah for an 8S setup, I am able to fly a normal 4 min flight duration, I notice the smaller capacity pack is always around .05 volts lower. Typically 3.77 to the larger packs' 3.82, so apart from the extra dead weight, it's really not an issue at all. If you're really concerned you could add a little voltage telemetry sensor to the smaller pack to monitor it as an added safety measure.
Nov 10, 2017, 03:33 PM
RELAX. You'll live longer
785boats's Avatar
If you are intent on doing it, only charge the Hyperion pack up to 4.2v/cell to match the Revo pack.
This will also lose about 500mah of capacity so the flight time will be reduced a bit more.
But at least the voltages & the discharge rates will be more even. But still base your time around the smaller 4400mah pack.
Nov 10, 2017, 06:49 PM
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kell490's Avatar
Ended up not doing it because the revo battery didn't fit right I picked up a new Hyperion to replace the one I'm having a issue with some good information here if someone else needs to know.
Nov 17, 2017, 11:48 AM
Proud to eat Kraut ;-)
Julez's Avatar
Generally it's not a problem if you find a way to operate each battery within specs.


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