Good points.
Bob did make the point that the smaller the battery, the more frequent the
load checking to avoid dead battery in air syndrome. B&C do not quote CCA
on their website, and I've asked them to provide such information for
comparison.
Shaun Simpkins
A207
----- Original Message -----
From: "Fred Fillinger" <fillinger@ameritech.net>
>
> It's odd they use that ampere-hour stuff (mere capacity), whereas for
> cranking engines, internal resistance is as important per Nuckolls, so
> stuff like CCA - cold cranking amps - is the spec on batteries for
> engine applications. Cranking amps reflect both capacity and internal
> resistance, and the Odyssey PC625 I have is 265 CCA (440 HCA - "hot"
> at 80F). Cranking amps is the amps it delivers for 30 sec. while
> maintaining 10-point-something volts. "AH" is based on something like
> a 20-hour discharge rate, but other specs suggest the PC625 is about
> 13AH. That's also why Nuckolls says even an 8AH batt, if RG and hence
> low internal resistance, will work, but I would add not for too much
> cranking nor allow for in-service degradation.
>
> Also, the 50W starter draw would be average. If you've ever seen the
> wild needle dance on those little induction ammeters placed on a
> battery cable, it's the compression stroke that hurts, and quick
> starting is oomph into that stroke rather than average cranking RPM,
> else no one could hand-prop an airplane. And Bob H. notes the effect
> of 50% more oomphs per revolution on his six-banger. That's what a
> higher CCA provides.
>
> Regards,
> Fred F.
>
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