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Old 09-28-2013
Rusty123 Rusty123 is offline
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Re: How big of a starting battery do I really need?

I did some shopping and research today - here's what I found:

There seems to be two general capacities of U1 batteries available: around 350 CCA for about $55, and around 250 CCA for about $35.

The smallest automotive battery at Costco was a group 35: around 600 CCA for about $65. While the price and capacity compares favorably to the U1, I don't think I have the room for it. So I'm leaning towards a larger capacity U1.

(BTW, my Yanmar manual calls for a battery with a capacity of 70 AH (no rate mentioned). These small batteries don't seem to list AH capacity, so that's not much use).

One concern I have about all of these small batteries: they seem to invariably be maintenance free (or even sealed), which concerns me a bit since the start battery will be paralleled with my house bank during charging. I'm still learning about the dynamics of batteries and charging systems, but something tells me that paralleling a small, almost always fully charged battery that cannot be topped off; to a large, sometimes substantially discharged battery bank; using the same charger for both, might be a mistake.

Is my concern warranted?
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