David Massey wrote:
>
> P.P.S. CCA is not a measure of capacity. That is measured in Amp-Hours.
> Few manufacturers list the A-H rating of the battery in a prominent way.
Last time I looked, most battery manufacturers were posting "Reserve
Capacity" or RC, which is an indication of battery capacity. RC is
given in minutes, and is the number of minutes a battery can deliver a
fixed current before reaching a specified terminal voltage. (Sorry, I
don't recall the current or voltage off-hand.) It's still really an
amp-hour rating, just presented in a different fashion.
Although IMO the switch to RC was simply to confuse the battery buying
public, there is actually a rationale for it : RC is supposed to more
accurately reflect what users are actually interested in : how long can
you leave your headlights on and still start the car ?
The problem with amp-hour ratings of lead-acid car batteries is that the
number varies greatly with how fast the battery is discharged. The
previous standard was the "20-hour" rating, where the discharge current
was fixed at the value that the battery could deliver for 20 hours. The
new 'RC' standard instead uses the same current for all batteries. The
name and units were changed mostly to prevent confusion with the old
standard (which typically resulted in higher AH ratings than the new
one).
Randall
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