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Old 06-24-2009, 01:49 PM   #9 (permalink)
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Originally Posted by wjdennis View Post
Black Panther wrote: The idea is that the second pack would be smaller capacity, but newer tech with a high C rating and the same nominal voltage. if preserved as a fresh pack until that hill, when you paralleled them, the second pack should supply the majority of the current simply by the balance of each packs capability to deliver the current. your low C pack will tend to sag as it approaches its c rating and when paralleled to a high C pack which maintains the voltage, the low C pack will not be able to push as much current because the paralleled voltage is higher than what it can push that much current in to.

Without the second pack connected, the voltage would drop more under load and your low C pack delivers more current at the expense of battery stress.

With the high C pack connected, the high C pack will not stress until much higher current loads, so it can keep the paralleled voltage at a respectable level until you have nearly depleted them.

I hope this clarifies it somewhat.
Black Panther,
I'm not saving the second pack until a hill. Cruising at highway speed requires 100A. I want the lower-C pack to deliver no more than 70A, ever. So while cruising, the higher-C pack will be delivering 30A, and the lower-C pack 70A through the controller. When the hill comes, the higher-C pack will deliver more amps, with the lower-C pack remaining at 70A through the controller.

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