# beginner help raising voltage from 2-3V to ~14V

Discussion in 'The Projects Forum' started by rpistudent, Nov 30, 2010.

1. ### rpistudent Thread Starter New Member

Nov 30, 2010
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I need help with a project. I have no practical electrical knowledge and I do not really understand what I need. First, we are generating electricity using a generator. It will be rectified into DC.
At this point the electricity will likely be 2-3V and ~20A.
We need to raise this voltage to between 13-15V and have as high a current as possible.
This Voltage is needed to charge a 12V gel-cell battery.
The battery can accept very high currents.

How do I do this.
I tried to look at voltage regulators but none fit this criteria and can be adjusted to these settings. Any help and advice are appreciated.

Last edited: Nov 30, 2010
2. ### thatoneguy AAC Fanatic!

Feb 19, 2009
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A search for "boost mode regulator" will give ideas. What is the source of the 2-3V? Is it straight DC, or something from a generator that varies between 2 and 3 V?

Efficiency won't be the greatest, you will lose over 10% minimum.

Rearranging the source, such as putting solar panels in series instead of parallel, will give better results.

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3. ### rpistudent Thread Starter New Member

Nov 30, 2010
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the input voltage is coming from a generator so it will vary a little between 2 and 3.

4. ### rpistudent Thread Starter New Member

Nov 30, 2010
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i cant seem to find any products that can handle a current above 1A (and im looking for atleast above 5A) and accept an input voltage that low (2-3V). Are there products like this on the market or are these specs so not normal where there wouldnt be any normal use for them.

5. ### thatoneguy AAC Fanatic!

Feb 19, 2009
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What type of generator? Homopolar?

Is it a DC motor being run as a generator?

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6. ### rpistudent Thread Starter New Member

Nov 30, 2010
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its a 3-phase AC electric generator (using magnets). It is built similar to a wind generator. This goes to a rectifier that converts it to DC.
At that point I am getting a wire with approx. 2.6V and 20A DC current, which I need to change to ~14V DC current

7. ### thatoneguy AAC Fanatic!

Feb 19, 2009
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In that case, you may be better off using transformers to step up the 3 phases to a useful level, then rectify and regulate the output. Power will still be the same, an increase in voltage will mean less current for the same power.

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8. ### SgtWookie Expert

Jul 17, 2007
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What is the frequency of your 3-phase output? If it is low, you will need large, heavy transformers. If it's reasonably high frequency, you may be able to make a much more compact transformers.

9. ### wayneh Expert

Sep 9, 2010
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Actually there will be a big power gain by stepping up voltage first, because of the big loss the OP is suffering in his rectifier. This could easily be equal to the present output, as the diodes could easily be dropping over 2v at that current. I'm not saying you'll recover all this with the step up, just that there is some potential and it makes sense to step up BEFORE rectifying.

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