Even smaller!

Ideas and questions about MintyBoost kits

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alavin89
 
Posts: 6
Joined: Tue Apr 08, 2014 8:06 pm

Even smaller!

Post by alavin89 »

Hi, my MintyBoost works great, but now I'm trying to make a minimalist phone charger. I'm trying to use 3V button cells in series so I don't need the step up voltage regulator. Right now I just have power and ground to the respective USB terminals, with a 100uF cap in parallel. My device says it's charging, but the power % is decreasing! Any ideas? Please help, I'm a bit of a newb and trying to learn as I go.

Thank you,
Alex

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adafruit_support_bill
 
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Joined: Sat Feb 07, 2009 10:11 am

Re: Even smaller!

Post by adafruit_support_bill »

You are not going to get the kind of current you need to charge a phone from button cells. Most phones need at least 500mA and those cells are designed for discharge rates in the micro-amp range. They have a pretty high internal resistance, so if you try to discharge them at more than a few milliamps, you get a large voltage drop and a decrease in effective capacity.

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