Nimh battery charge/discharge?

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ShowMaster
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Nimh battery charge/discharge?

Post by ShowMaster »

I'm going to use a 2400ma HK LSD 4 cell pack for my nitro plane airborne pack. The receiver will be a d8R. I'm also using switch glow glow plug driver off of the same pack to save weight.
The glow driver claims to use 120MA for every 5 min on delivering 1.5A to the plug or 1.5A/hr.
I plane to have the plug lite up every time the throttle goes below 50%. I'm ok with only several flights per charge and tipping off the pack when not flying or just swapping packs.
I started building this plane in 1982 and the OS .46 long stroke new engine may cutout at low throttle. If it survives the test and trim flights I'll sort out or replace the carb.
So what I need help with is some solid or fuzzy battery capacity math.
What's a good charge rate to insure 100% charging and what should I expect as a practical under load Ma rating and at what cutoff voltage?
I'm planning to cycle the pack 3 times before using it btw.
We know the d8R is good to 3v and with telemetry I'll know when the pack is close to 4v.
The glow driver will be on ch6 so I can control its on/off coupling to the throttle channel if I get a low rec battery warning.
I think I've pretty much got the logistics worked out except for knowing what to expect from the Nimh pack as far as usable 2400ma in this application.
A typical 10 min flight and long taxi way at idle will probably have the glow driver on for 5 min per flight.
Any ideas on charge/discharge practice values for a 2400ma LSD pack?
Thanks

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jhsa
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Re: Nimh battery charge/discharge?

Post by jhsa »

If my opinion matters, I don't like the idea of a single pack for receiver/servos and glow plug driver..

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MikeB
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Re: Nimh battery charge/discharge?

Post by MikeB »

I'd agree. I can think of several failure modes which could result in short in the glow plug driver resulting in a very rapid discharge and resulting loss of control.
I'd consider two smaller batteries (AAA around 1000mAh) one for the radio and one for the glow plug. About the same weight.

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erskyTx/er9x developer
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ShowMaster
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Re: Nimh battery charge/discharge?

Post by ShowMaster »

Ok, I'll rethink it. I'm replacing a 1100ma 4 cell nicad pack that's very heavy, I'll weigh 2 AA Nimh packs or one AA & one AAA pack be the nicad pack.
The glow driver is able to use other sources if the red wire is isolated in a throttle Y cable.
I could also use a 2 cell lipo glow battery since the d8r has the A2 port available to monitor the lipo.

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