# Math Help ( Hey, I'm new to this stuff ) Thought it was a simple multiplication problem

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scouttster
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Joined: 12/19/2011
Points: 14

Gentleman is selling batteries as reads:
\$58.20 for 28 = 3.7v 2400mah batteries.
Enough to make a 25.9v 9.6ah pack that works with the EZip 24v controller!

I figured he arrived at his figures by 28 X 3.7 for the voltage and 28 X 2.4 for the amphours. I was way wrong.. Can someone explain, how he arrived at 25.9 Volts and 9.6ah?
Thanks, I'm new to all this and just trying to learn.

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Spaceangel
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Joined: 07/15/2009
Points: 497
Re: Math Help ( Hey, I'm new to this stuff ) Thought it ...

I think I lost you in your typing of the number of cells and voltage pack? I want to convert my scoot to LiFePO4 and I know 4 lithium cells = 12.8 volt nominal so times 5 = a tad more than 60 volt pack but close enough I think. What exactly do you need? I am going to cut my frame to make testing and replacing easier.
Russell

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mf70
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Joined: 12/01/2006
Points: 712
Re: Math Help ( Hey, I'm new to this stuff ) Thought it ...

He's building four serial strings of seven cells, and running the four strings in parallel:

7 x 3.7V = 25.9V

4 x 2.4AH = 9.6 AH

The math is correct.

Mark

mf70
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Joined: 12/01/2006
Points: 712
Re: Math Help ( Hey, I'm new to this stuff ) Thought it ...

Oops. The board won't let me edit. To add, now, whether your simple charger will keep all these cells balanced without a BMI is another question. I don't think it will, and that's part of the reason I've still got lead in my sled.

Mark (again)

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