mckibben

Hi I am going from nicd rx packs to nimh packs 4.8v I have been reading about nimh charging. Can some one give me a number on fast charging a nimh pack. I am using a 2000 mha pack from tower hobbies. And i have a very good charger. I know that a nimh pack can not be fast charged like a nicd pack. My deal is i am at the flying field. battery pack is down and i want to charge it up to fly some more. How high can i set my charger to get the rx pack charged up in short time and not destroy the pack?
Thanks[8D]

drumduan

I would go for 1C.....

Mikecam

1/10 C would be the best but you could try a higher rating just feel the pack while charging and if it gets hot it's too much, warm is fine.


Fixed my mistake.

mckibben

I do not get what 1C means It's a 2000 mah battery does that mean i can fast charge it at 2000 mah. All i know about the battery pack is it is nimh 4.8 2000 mah Slow charge is 200mah. Fast charge is what? My charger does not have 1c on it.

drumduan

2000mah is how much energy is stored in it. 2000mah is 2amps. By definition that battery could deliver 2amps, constantly, for 1hour.

So if your set up uses 20amps at full throttle you could full throttle for 2/20th of an hour (60mins/20 = 3mins. 3x2=6min flight time). In reality this would be slightly less due to mechanical inefficiencies and the fact that the higher the amp draw the less efficient but that is more than enough detail for now?!

1C means 1xcapacitiy of the battery. So a nimh can be charged at about 1C, so a 2000mah pack can be charged at 2amps taking about an hour to charge.  A 2000mah lipo that can be charged at 2C would be charged at 4amps and take 30mins.

1C = 1hr to charge, 2C = 30mins to charge, 3C= 20mins to charge, 4C= 15mins to charge etc.

It is best to charge batteries almost as slowly as you have time for (too slow a rate and it will never charge fully, too fast and you will never be allowed inside again!!)

So, 1C for your 2000mah nimh would be charge it at max of 2amps. If you have more than an hour to spare I would charge at 1/2C which is.....................1amp and it should take 2hrs.

Mikecam

Sorry late at night. Fixed my post to read 1/10 C and not 1C. drum is right and 1/2 C or 1000 mAh or 1 amp charge for a 2000 mAh nimh should be fine. You won't take the whole 2000 mAh out so if you only take out 1000 mAh then charging at 1000 mAh will take one hour.

Also do a discharge and make sure you are still getting close to 2000 mAh out of the battery.

If your charger can do life battery's they are even better then the nimh and worth some reading up on.

mckibben

Thank you so very much for the info about charging this kind of battery. As time goes on i plan to use nimh on all my rx and tx stuff.
Thank you, Tom

Goldenduff

Eneloop Sanyo are the best nimh for transmitters.