Charging a 2 cell nimh 2.4v with a 4.8 reciver charger

[Giuseppe Saroli]

Hi I have been told that I can charge my on board 2 cell 3.800 nimh battery's that I use for my on board glow with a standard receiver 4.8v charger is this correct ! Thanks you in advance

[iqon]

.....yes any size nimh

[Giuseppe Saroli]

I am confused is not the size of the battery but the voltage the rx charger is for 4 cell 4.8V so it must push 4.8 volt to charge 4 cell at 300 miliamps I am going to connect it to a 2.4V surely is to much and might damage the 2 battery's

So confused Thanks

[Geoff S]

The charge regime for a NiMh battery is for a constant current not a constant voltage so, to some extent the voltage is irrelevant. However, I assume you're using a simple wall charger with no charge detection (there's slight negative slope to the voltage when NiCads and NiMh batteries reach full charge which, on a more sophisticated charger, ends the process) so you need to time it carefully. Personally I'd throw it away and buy a decent charger which are quite cheap anyway. Then you'd really know the state of your battery before flight and have some confidence that it really is fully charged.

Geoff

[Giuseppe Saroli]

Thanks Geoff I have a new charger that came with my hitec sport 6 and is design for nimh tx and rx and has got 2 light and the rx light goes off when fully charged I think would this be ok ,otherwise I don't mind keeping a eye on it, if is rated at 300 milliamps how long would it take to charge my 2 nimh battery rated at 3.800 milliamps each thanks again I hope I am making sense here

[Martin Harris - Moderator]

It depends on how much you've taken out of it during the last session.

Geoff's advice is very sound but if you're charging a 3.8Ah battery at 300 mA then you won't do much harm by charging a little beyond full capacity.

Unless you recharge using a "smart" charger, you won't really have much idea how much capacity is used during a typical flight so there's a lot of guesswork involved. A small "smart" charger from one of the internet suppliers will be very cheap and a good investment. Keep the wall charger for initial forming charges (which are really just full charges with a bit extra to ensure all cells are topped up) and use the new one for all your normal charging at appropriate rates (not too low on NiMH to avoid "false peaks " - between 1/2 and 1 C (i.e. 1900 mA to 3800 mA in your case) is a decent guide.

(Just noticed your info about the light going off on the charger but I can't see any indication that it peak detects - at a 15 hour charge rate as advised by the Hitec manual on line it would be likely to be rather hit and miss if it does!)

Edited By Martin Harris on 04/11/2015 16:03:56