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When should they be replaced ?

Old 07-24-2011, 09:10 AM
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2robinhood
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Default When should they be replaced ?

When should RX battery ( Nimh ) packs be replaced ?

I am running two 35%ers with the same set-up.
Two 6V 2700mah Nimh packs on the RX.
I am having absolutely no issues with them, they just are into their fourth flying season.
If the voltage is there and the mah's are there ( cycling them through a discharge that reads the mah in the packs ) are they still good to go or should they be replace after a certain amount of time ?
Old 07-24-2011, 11:34 AM
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krayzc-RCU
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Default RE: When should they be replaced ?

i would google that question as i have seen it out there seems they rec. when a certain percentage is loss
Old 07-24-2011, 12:50 PM
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pe reivers
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Default RE: When should they be replaced ?

With NiCad's the life span is about 8 years. I have no data for NiMH. My educated guess would be to check the energy storage capacity under load. If down to 80% I would use the batteries for less critical devices.
Old 07-24-2011, 03:16 PM
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Jezmo
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Default RE: When should they be replaced ?

I used dual 6V 2700 mAh NiMH's before going to A123's in my 50cc Extra. The NiMH's started to show distress on my CBAIII battery analyzer somewhere in the fourth year. At lower current draw they would deliver close to the rated capacity but really started to fade quickly when pressed hard. I would look at new packs if you have no way to test them with at least an 8 amp load. Mine would do 8 to 10 amps pretty easy when new without falling below 1.0 volt per cell but by the fourth year would fall below 1.0 volt per cell with as little as 5 amps load. In my 50cc with power hungry digital servos that just wasn't enough for my tastes. After replacing the packs with dual A123 2300's the difference was amazing in control response in-flight. If you have a way of hanging 7 or 8 amps on them and testing the voltage then as long as they don't depress to less than 1.0 volt per cell and have 80% capacity with a decent load as Pe said (I'd say at around a 500ma load), I would keep using them until they fall below those specs.


P.S. Be careful with the little servo type connectors many packs come with, they will get hot and melt somewhere around 5 to 6 amps. I used to use the small Deans connectors on mine for a bit more robustness.

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