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post #9 of Old 10-07-2012
Maine Sail
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Re: Battery capacity - Peukert stuff

Originally Posted by asdf38 View Post
Stu, that's all right but previously you said this:
"Anyway, the answer to your question is that a bigger bank, twice the size, would have twice the time to go based on similar loads. That's all."

That's either contradicting the reasoning in the passage you just quoted, or it's confusing.

Again to the OP's question, he's right, doubling the capacity with either an additional cell or a larger cell results in a 10% "bonus" capacity because of this equation.
If we look at capacity, and the average load, on a bank with a Peukert of 1.25, we can look at it like this:

The boat uses an average of a 5A load.

100Ah bank at a 5A load will deliver 100 Ah's. (50 Ah's usable to 50% SOC)

200Ah bank at a 5A load will deliver 238 Ah's (138 Ah's usable to 50% SOC)

300Ah bank at a 5A load will deliver 395 Ah's (245 Ah's usable to 50% SOC)

400 Ah bank at a 5A load will deliver 566 Ah's (366 Ah's usable to 50% SOC)

-Maine Sail / CS-36T

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