using other batteries

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edk4971
 
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Joined: Sun May 06, 2007 8:24 pm

using other batteries

Post by edk4971 »

Hello,
I'm thinking about starting a project for an RF remote (arduino + RF module + Mythtv). I've already built a minty boost, and I'm wondering 3 things:

First could I use a battery other than AA's? I have an old RAZR laying around, I was going to steal the battery out of that. It puts out 3.6V, would that damage the mintyboost circuit?

Second, I'm not an EE, just an IT guy, so if it isn't too much trouble could you give me some pointers on how to build the charging circuit? In my head I have a magic picture of me connecting the +5v and GND from the phone charger to the + and - on the battery but Murphy tells me it's a little more complicated than that. I did find one link that looks promising to my limited technical knowledge: http://www.afrotechmods.com/reallycheap ... /batts.htm
and as an added bonus... pretty cheap to build
Of course if this really is not even in the ballpark, I'll pick up an external battery charger and just rip it apart :-)

Third, when I add the charger voltage to the circuit, assuming it's around 5V, will that damage the minty boost or interrupt power to the arduino? My basic understanding of Ohm's Law tells me since they're connected in parallel the voltage will go up to 5V from the charger (since it is bigger) and the Amps will be the sum of the battery (??mA, not sure how to figure it out, but it's 820mAh if that helps) and the charger (which says it's 550mA)

I'm really hoping this project is possible with my limited skills, and I know I'm asking a lot so I don't mind if you tell me bugger off if I'm in too far over my head :-) Really what I'm trying to do here is make a rechargeable battery pack for my Arduino by modifying your sweet (no pun intended) Minty Boost

Thanks!
Elliott

adafruit
 
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Re: using other batteries

Post by adafruit »

edk4971 wrote: First could I use a battery other than AA's? I have an old RAZR laying around, I was going to steal the battery out of that. It puts out 3.6V, would that damage the mintyboost circuit?
a 3.6V battery is AOK
Second, I'm not an EE, just an IT guy, so if it isn't too much trouble could you give me some pointers on how to build the charging circuit?
for what? a LiIon? you should use an official charger. otherwise you stand a very good chance of damaging the battery.

Third, when I add the charger voltage to the circuit, assuming it's around 5V, will that damage the minty boost or interrupt power to the arduino?
no, a li-ion charger gives out 3.2-4.2V so it should be OK to run the charger onto the battery onto a mintyboost to get 5V out.

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edk4971
 
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Post by edk4971 »

great, roger, and thanks a lot!

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