"DSK" wrote ...
..... a simpler rule of thumb is to crank the
engine
over while watching a volt meter (a digital mulitmeter set to record
minimum V works
best) and see if the voltage drops below 10.5V. If yes, you need either
more battery
or a dedicated starting battery.

-rick- wrote:
Thanks Doug.

Are you measuring the voltage at the battery or the starter during this
test?

At the battery, it's most important what the battery "sees" as it's voltage
drop; assuming the current is enough to crank & start the thing. Not a bad idea
to check both places.

Fair Skies-
Doug King