Really stupid battery question, but...

[Talonclaw117]

I know I don't need to discharge NiMHs, but I've been using NiCADs for a while, and I've forgotten if NiMHs heat up if you keep them charging for too long. I use a Zero One trickle charger. Cheers.

[Stealthbomber]

All batteries heat up if you charget hem too fast or for too long.

 

Although NiMh batteries don't suffer with memory effect (which means you don't need to discharge them) it is often worth discharging them simply to make sure your charger doesn't over-cook them.

[The General]

Yes, NiMH batteries heat up. However its not really a sign of damage as much as the cells are full. Over charging will cause damage though.

 

Its really bad news using a trickle charger with this type of battery to be honest. You are not going to get the performance from the battery trickle charging. Some suggest you are conditioning the battery for a low drain application doing this. Airsoft is a high drain application. Charging at a higher level than trickle would make more sense.

 

As an example I charge my 1500 mah mini batteries at 1.5amps. As long as you dont go over the mah to amps rule and its a thermal/delta sensing smart charger, its safe as far as I am aware.

 

1200 mah 1.2 amps

 

600 mah, 0.6 amps

 

and so on, but I dont go much above 2 amps even with large batteries at 4600 mah.

 

You need a smart charger where you can adjust the input power.

 

I use a Propeak 2500 Varipulse and its so easy to use.

[England Wonder]

Batteries will get warmer when being charged and discharged, it's just how it it. You only need to worry if they get really hot.

 

The General's suggestion of charging currents seems rather high to me. I know the componant shop 1500mah packs have a max charge rate of 1.5 amps but it will reduce the life span to always charge them that fast. I go for about 1 amp which takes a little over two hours.

 

what's the trickle charge rate of the charger? If you get a good charger it will have delta V detection. Mine charges to this and then trickle charges at 100ma (or 50ma depending). Also NiMH cells do have memory, just no where near as much as NiCd.

I noticed this with my bike lights (5ah 14.4v battery) when it was used 5days a week through the winter.

 

Also worth noting that NiMH cells are best stored at 40% charged if being stored for long periods of time. I do a couple of charge/discharge cycles while packs aren't in use.