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Question about batteries

Hi again,

I have a RC Apache helicopter from JayCar (Australia) and 'I think' the battery is dead, seeing it won't turn on. I know its has 7.4 volts and is 850Ah, but to replace the battery would cost $50.

Would it be possible to replace the battery with 5 1.5v AA or AAA bateries instead?


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You need energy dense.  How much extra weight is that going to add, and whats the overall weight of your heli?  You may want to snag an energizer datasheet and see what the drop in Ah is, as that will limit flight time alot I'm guessing.

Try connecting another source of power to the helicopter just to make sure the battery is the problem. Make sure polarity is correct and the voltage is between about 6-8V. If it does turn on your best bet is to try getting a similar battery at hobbyking. Look for a 2S (2 cell Series) lipo of the same dimension. They should have plenty of batteries that will work just as good as the original. Stay away from AA AAA if you want to use the original charger.

Your original LiPo battery (I think that's a LiPo anyway) is capable of delivering its power mucher faster than any off the shelf AA battery. Your 850 mAh might very well be able to deliver up to 12 Ampere. Or even more. And choppers need it. That's why Jaycar is charging you $50 for it.

Shopping online will get you better deal.

but to test if it is the battery can i use AA AAAs?


I have in my very hand, (3) 7.4v 900mAh lipo batteries and I paid $21 USD for them (all 3, 7 bucks a piece). How in the world can such a small lipo cost so much? Is it a Australian thing? Exchange rate? Can't get 'em from China?

Even my big lipos (for my plane) are not that much... 11.4v  2600mAh (and I paid around $16 for them)



It`s an Australian thing. There are no cheap electronics shops that run a retail store front here. We especially get price gouged on batteries and ICs in particular. $25 USD for an atmega168 which costs $4 elsewhere is a good example.

$25 dollar chips and nation-wide monthly bandwidth limits... My heart goes out...