> At 05:11 PM 2/16/2005 +1000, you wrote:
> >Bill,
>
>What would you expect the battery to show under starting load.
>
>George ( down under)
>
>
The Hawker Odyssey PC 680 that
most folks use has an internal
> resistance of 0.007 Ohms. A typical
starter draws perhaps 200 amps in cold
> weather. This means that the
battery voltage will drop 200 x 0.007 = 1.4
> volt initially. If the
battery is fully charged,the voltage will be
> about 12.8 - 1.4
= 11.4 volts for the first few of blades. As you
> continue to
crank, the voltage will continue to decline. If you continue to
> draw
200 amps for 60 seconds (at 77 degrees F) the battery voltage will sag
>
down to 7.2 volts.
>
>
If you do crank for this long,
it might take as long as ten
> minutes for the battery to charge back up
to 13 volts. (Of course this
> depends on the size of your alternator and
the draw from other loads on the
> system.)
>
>
There are nifty charts and
graphs at:
>
>
http://www.batterymart.com/pdf_files/odyssey_guide.pdf>
>
Went to this site and is good, however no weights
are given. One curious thing, the 625 seems to outperform the 680 in CCA, CA,
HCA, and reserve but not in PHCA. Looks to me if you don't need to few extra
cranking amps, the 625 would be the battery of choice (it should be
lighter?)