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# boost volts deflate amps? Answered

I recently came to know about a "mintyboost" from "steveastrouk"( a very helpful and trusted member of instructables).It boosts up volts while bringing down amps very much like a step up transformer.Well I've got 2 AA rechargeable batteries rated 1.2 volts and 1900mAh.So here's my first question-I connect these batteries in parallel and they give out a total of 2.4 volts okay fine....but what about the amps?will they get added up like volts and produce 3800mAh current?The latter part-I need to boost this 2.4 volts to 5 volts by bringing down the amps(any value is fine as long as its above 0.7 Amps).Could you please give me a specificated instruction on how to do this?If to use a "mintyboost"what software should I use to calculate the required values and......... the rest...... Pls don't think I'm lazy.I really want to do this so badly...

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## 7 Replies

2xAA rechargeable in series gives 2.4V @ TOTAL 1900mAh.
2xAA rechargeable in parallel gives 1.2V @ TOTAL 3800mAh.
^^ those numbers are volts and capacity, not amps.

The mintyboost will use series (so 2.4v) and will output 500mA at 5V. Volts times amps = watts.
mintyboost will output about 2.5W. (0.5A * 5V)
Assuming it's 80% efficient...it will draw about (2.5W/80%) = 3.1 watts...
at 2.4 input volts, 3.1 watts will draw 1.3 amps from the batteries. (3.1/2.4).

The mintyboost is a kit. You do no calculation - you just put it together (soldering required) and add batteries.
Since you have 1900mAh batteries, at 1300mA draw, they will last 1.46 hours. Capacity divided by current = runtime. (mAh / mA = h)

Thank you mpilchfamily for that nice diagram and Frollard for your help.I also thank steveastrouk and iceng for their contributions.I convey my gratitude to all of you because ya'll have helped me equally and I can't choose a best answer!

iceng (author)2013-01-22
Good tutelage Question !

Everyone has pointed out that similar same batteries ;
• In series add voltage current stays the same
• In parallel add current  voltage stays the same

mpilchfamily (author)2013-01-22

If you connect the batteries in parallel you won't get 2.4V you'll only get 1.2V. When you connect 2 batteries of the same type in parallel you get double the available amperage. If you connect 2 batteries of the same type in series you get double the voltage.

The 1900mAh is a rating of how long the batteries will last. So they can output up to 1.9A over the course of an hour before running out of power. If less amperage is being drawn than they will last longer. If you put your 2 batteries in parallel than you will have 1.2V going to the minty boost with up to 3.8A that can be output in an hour running the batteries dry.

So if your looking to make the minty boost last longer you'll need 4 batteries. Wire the batteries so that you have 2 pairs of batteries that are wired in parallel and then wire those pairs together in series. I attached an image to help you see how it would work.

steveastrouk (author)2013-01-22

JFYI, the 1900mAHr is usually measured at a 10 hour rate - they'll hold considerably less energy if you run it out in an hour, because of IR drop in the internal resistance, and chemistry reasons.

mpilchfamily (author)2013-01-22

Thanks!

mpilchfamily (author)2013-01-22

Here is the image.

This will give you longer run time that a single pair of batteries would. Just make sure the batteries are all the same and brand new.