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HelicopterRadio - Servo - Gyro - Gov - Batt › Have I damaged it?
11-27-2007 06:44 PM  10 years agoPost 1
400driver

rrApprentice

uk/ Spain

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hi,
I have a United hobbies 2500mah 3 cell lipo for my Futaba Tx. The battery has been working really well and the first charge has lasted about 3 months.
I discharged the lipo in the Tx down to 9.9 volts and then put it on charge. The charger cutoff at 2500mah, now i try never to over discharge lipos..have i overdischarged this one as so much went back in. My aim is always to put no more than 80% back in to any lipos.
Is it possible that the pack has been under labelled? I,e its actually a 2600 mah pack?
On the subject of UH i have just receivved a replacement pack from them after i sent them pictures of a puffed pack!They didnt even want the old one. They said that that particular run had some faults.

More days at home would be nice!

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11-27-2007 08:03 PM  10 years agoPost 2
helimatt

rrElite Veteran

Lafayette, IN

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Couple questions:

Did you purposely discharge to 9.9V in order to cycle the pack (as in Nicad practice)? Not necessary for lipos. You probably knew that already but I just thought I'd mention it.

If it didn't puff, I doubt you've seriously degraded the pack and if you did it would show as reduced capacity. There is a lot of "spare" capacity for a TX pack so just watch the voltage levels as you use it. Better yet, cycle it on your charger to monitor actual capacity at a typical load.

The TX does not draw much current from the pack so it gets an easy ride. Discharging more than 80% in those conditions is far less serious than for a flight motor duty where high there is high current draw.

Never, ever, ever, ever give up.

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11-27-2007 08:07 PM  10 years agoPost 3
400driver

rrApprentice

uk/ Spain

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I just felt at 9.9 it was about time to charge the pack.The pack looks perfect as before, so it doesnt show any outward signs of damage. I will stop at just over 10 volts next time and see what goes back in.
Thanks

More days at home would be nice!

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11-27-2007 10:18 PM  10 years agoPost 4
wannabfishin02

rrApprentice

barnhart, Mo-63012

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Im not sure about that specific battery, but 3.3 volts per cell shouldnt be too much of a discharge on a lipo pack. I think your plenty safe there.

A bad day of flying is better than a good day of work

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11-28-2007 12:31 PM  10 years agoPost 5
400driver

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uk/ Spain

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thats what i thought, so was surprised when 2500 mah went back in!

More days at home would be nice!

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11-28-2007 12:42 PM  10 years agoPost 6
copperclad

rrElite Veteran

NY

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hi
you understand that the minimum voltage has to be measured under load , if you are measuring with a voltmeter while the battery is at rest you will get a much higher reading , hth , dana

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11-28-2007 09:49 PM  10 years agoPost 7
wannabfishin02

rrApprentice

barnhart, Mo-63012

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I think he was using the radio voltage meter as a tester which would put it under a very light load. Even at that, I would think 3.3v per cell would be ok. The mah put back in wouldnt be a huge concern if it were mine, but I may not run the pack as low in the future so as not to shorten the lifespan of the battery pack.

A bad day of flying is better than a good day of work

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11-29-2007 03:41 AM  10 years agoPost 8
400driver

rrApprentice

uk/ Spain

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Yes, the reading was taken off the panel of my 9CHp.

More days at home would be nice!

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HelicopterRadio - Servo - Gyro - Gov - Batt › Have I damaged it?
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