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Lipo swelling on discharge

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Lipo swelling on discharge

Old 05-30-2005, 05:06 PM
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rcAirTycoon
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Default Lipo swelling on discharge

Hey all.

I'm new to electric flight and have a SIG Kadet EP42 that I have powered with a Thunder Power 1320 mAh 11.1 volt lipo.

I don't have a lipo cutoff set up yet so the first time I flew it I only had it up around five minutes to prevent over-discharge. When it got down I checked the battery and noticed it was hot and one cell was swelling... The swelling went down and I was able to charge it back to full capacity with my GP Triton with no heat or swelling. I've flown it two times since and both times the same cell swells and the battery gets hot. I checked voltage upon landing and the last time the battery was still reading 11.1 volts (this was after around 5 minutes of flight). I've decided to stop flying it until I get some answers.

Anybody have any idea why this battery might be behaving this way?

J
Old 05-30-2005, 05:43 PM
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Fly-n-3D
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Default RE: Lipo swelling on discharge

You might have damanged the battery.
Old 05-30-2005, 06:21 PM
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exeter_acres
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Default RE: Lipo swelling on discharge

what setup are you using? motor? prop? etc?

Do you use a watt meter (if not...buy one..they are worth it) to measure the amps/watts? What sort of current are you pulling?
Old 05-30-2005, 10:46 PM
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rcAirTycoon
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Default RE: Lipo swelling on discharge

it's the SIG super 400 motor and a 7 x 5 electric prop... I don't have a watt meter--but it sounds like I should go ahead and get one. I've looked around and could only find the Astro Flight Whatt Meter. Is that the one you were thinking of?

J
Old 05-31-2005, 01:05 AM
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Default RE: Lipo swelling on discharge

.I would advise not to fly with this battery until you check the current (amps) of the motor. Either the pack is overloaded or the cell you have swelling is defective. If swelling is noticed a fire could result in the next few minutes ( This is the reason for the warnings on Li-Po batteries). If you read some of the other posts concerning Li-Po fires, it is more than just a small flame and once a cell starts swelling it may be a few minutes before it becomes a flame thrower. A LI-PO pack should never exceed 140 deg F. I love the LI-PO packs, but just like glow fuel we must be cautious.

Vultch
Old 05-31-2005, 11:15 AM
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Default RE: Lipo swelling on discharge

thanks Vultch

that's more or less what I thought which is why I've stopped flying it! How will I be able to tell if the pack is overloaded?
Old 05-31-2005, 12:35 PM
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Default RE: Lipo swelling on discharge

You will need an ammeter to check the motor current. Disconnect one battery lead and connect the ammeter in series with it. then run the motor up to full power and check the amps drawn. Check the max C rating of the pack (ie. 1320mah X 10C = 13.2 amps). If you exceed the max rating of the pack then you are in an overloaded condition. the ammeter should be rated at least 20 amps. You could salvage one from an automobile battery charger, but leave some room for error as they are not the most accurate in the world. Hope this helps.

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