jcccc

Hi Group-

I have a bunch of Ni-MH AA and AAA batteries that have differing mAh and voltage ratings. Some are 1.25V and 2500 mAh and others are 1.2 V and 1700 mAh. But I don't have four of each size to make a 4 cell RX pack for my plane.

I have AAA with 1000 mAh and 700 mAh and some with 900 mAh.

What would happen if I used say 3 AA cells with 12.5V, 2500 mAh and one AA cell at 1.2V and 1700mAh to make an RX battery pack for my plane?

I guess my gerneral overall question is can I mix AA and AAA, 1.25 and 1.2 V and also differing mAh rating without harming anything while powering the RX and servos properly? And also, what is the result of slow charging them in the plane with a wall slow charger overnight?


Jcccc

rcairflr

My Feedback: (44)

Some of the cells would be undercharged, some would be overcharged, some would possibly get very hot. What you are trying to do is a no-no.

jcccc

Thanks rcairflr-

But can you elborate? Using a wall charger outputing 75 to 100 ma will hardly overcharge a 1700 or 2500mAh battery overnight. These chargers don't even overcharge the stock 600mAh Rx battery that comes with the radio overnight. I can better understand that 1.25V mixed with 1.2v batteries isn't a good idea.

Jc

GRANT ED

The different capacity batteries will discharge at slightly different rates. Is it really worth risking your plane? Spend the $2 to buy another cell so you have a matching pack.

nikg

I agree. If this was a car application I'd say knock yourself out, but planes are different. Don't take chances. Go get 4 decent new cells, make your own pack and for $10-$15 you can have some peace of mind instead of watching as your plane plumets to the ground screaming, "Why didn't you just buy the right cells??!!!"

BTW-I'm very frugal, but this seems like $$ wisely spent.

jcccc

so what if they discharge at slightly different rates. 1700 and 2500 mAh are much greater then the normal 600 mAh. These are new 'decent ' cells.

Can you explain further?

roblej

I agree with you, jcccc, nothing is gonna happen. If you were talking about 30A ó 40A discharge pack, 10SC elements, the above answers will be correct. But a RX pack, that usually does not discharge more than 200mA-300mA in a flying morning is going to work well enough mixing 1700mA and 2500mA elements. The pack is going to work as if all bateries would be 1700.

Obviously, try before, make some cicles of charge and discharge at low charge rate and check the temperature while charging.

swede47

My Feedback: (5)

Thats what I think too