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post #2 of Old 10-06-2012
Stu Jackson
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Re: Battery capacity - Peukert stuff

I don't think so. The P equation has only time and discharge amperage involved, Cp= I n t where n is a log function of I and t. It has nothing to do with battery bank capacity, it tells you the difference in time remaining when larger draws are made.

In fact, most battery monitors, if they're like the Links, only affect the time remaining function and NOT the amp hours consumed. Why? 'Cuz the only effect the Peukert function has is time remaining (which, of course, HAS to be based on any given battery bank capacity). That's simply linear -- bigger bank, bigger time remaining.

The Link manuals, especially the Link 2000, are pretty good at explaining this stuff. Xantrex has a discontinued models manual download section on their website.

The P equation essentially says: a higher load beyond the 20 hour rating takes more out of a bank, of ANY size, a lighter load takes less.

If you do the math on the exponential function, you'll see the differences.

In the real world, if you are imposing unusually larger loads on your house bank, it'll last less time because higher draws reduce the power availability, but only on time remaining, not on amp hours consumed.

That said, it really makes little difference.

Do the math.

Stu Jackson, Catalina 34, 1986, M25 engine, Rocna 10 (22#), Maple Bay, BC, Canada
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