Nimh rx battery maintenance?

[muscleflex]

Hi all,
I have an Eneloope receiver battery for my scale nitro heli.
It's a 4000mah 8 cell (parallel or series charged to double capacity?) AA batteries.

Now.. is there a way of me caring for them? Can I do discharge/charge cycles on them? I can't cycle them individually unfortunately as the cells are soldered but I just want to look after them well as I don't want to have to replace them because they've been neglected...

[Grumpy]

There aren't really any special rules for NiMh, if you charge with a good quality charger and avoid running them totally flat (which you wouldn't do with an Rx pack anyway) you should be good. People sometimes bang on about 'memory effect' and say to fully cycle them to prevent it, but if memory effect exists at all it only exists for NiCd batteries, not for NiMh

[myxiplx]

Yeah, these don't need monitoring as individual cells, I believe it's because they trickle charge until full and the chemistry naturally ensures the cells don't overcharge.

Just charge it and use it

[muscleflex]

Thanks both!
I just wanted to be sure as I actually have not flown this one since last summer so wasn't sure if I needed to cycle the batteries or just leave them as it is...

PS - is it safe to charge at 1c for NiMh or do I need to charge lower?

[heliphil]

I would not charge at 1C !!! trickle charge at 0.1 C

[horneteer]

General rule of thumb with NiMH packs is to always charge at 0.5C for peak performance and longevity. Trickle charging will be fine though. If you do charge at something like 0.5C, make sure you cycle it at least once before you use it in the air. Otherwise you run a high risk of undercharging. This is because NiMH chargers can easily misread the state of charge when an NiMH has been sitting around unused. Delta peak chargers almost always terminate the charge very early on packs that have not been woken up. NiMH batteries do suffer from memory effect, although not to the same extent at Nicad. NiMH batteries largely recover from this effect through occasional cycling.

[cycled]

You can't usually balance-charge NiMH packs. Normally this isn't an issue, but while checking cells with a multimeter I did find one cell of a four-set at 0V while others were charged. So it might be worth checking individual cells, especially if the charged full-voltage isn't quite what is expected.