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[~7.4V 800mAh] alkaline battery pack Answered

I need to create a battery pack with 7.4 to 7.5 volts and 800 mAh (or greater) in the lightest package possable with alkaline batteries. If circuitry is needed that would be fine.

Its for a mid-small sized RC Helecopter

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steveastroukBest Answer (author)2010-05-14

That's 5.92 Wh.... A 1.5 V 2300mA AA battery is 3.45 Wh, so two will meet your energy spec. Then a lightweight switcher can meet your voltage spec.

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user

And, where can I go to make this lightweight switcher?

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user

How good is your EE ? I'd build one round a chip like the LT3757, but it wouldn't be for the faint hearted.

Steve

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user

My Electrical Engineering is  advanced, I just need a good schematic and a list of what I need.

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user

Well the datasheet has what you need in principle. This is not  a design for running on a breadboard, it needs a PCB, and it has to be tiny, because this is a very fast switching circuit. There's a reference design in the datasheet, which should be modifiable for your requirements.

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steveastrouk (author)2010-05-14
user

It doesn't seem like this circuit will meet my demands. remember that it must power a RC Helicopter

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user

You didn't state the discharge current: I specified 800mA to begin with.

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user

The Helicopter is, E-Flite's Blade CX Twin-Rotor Helicopter

It has 2 FK-180 SH motors (Datasheet found here.)
And 2 Sub-Micro S60 Servos (Found here.)

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user

I'll guess at 3Amps then ?

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user

Well, I ran the Helli from my DC power supply and it went up to 4.5 amps at full throttle.

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user

NOW we have some working numbers !
;-)
Steve

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