> I noticed there is talk about 105 amp hours, what is the difference
between
> that and the New Interstate Marine/RV battery that came with that
1989 23
> footer I bought at the auction. The Interstate Battery does not say
amp hours
> rating, but has 975 CCA and 1150 MCA. What would the Amp hour rating
on this
> large battery?
Makers of deep cycle batteries have stopped using the AH rating system.
Everybody applied it differently and it was impossible to compare brands.
The new system, which everybody agreed to is called Reserve Capacity Minutes.
It is a rating based on a discharge rate of 25 amp per minute at 80 deg
temperature. A new Interstate Group 27 (13" long) battery has a Reserve
Capacity rating of 160
minutes. This is the battery used by Airstream for about the last 5
years.
When shopping for deep cycle batteries you can use the Reserve Capacity
rating to compare between brands. When Costco introduced their store brand
of batteries the Reserve Capacity rating was in direct proportion to the
cost. The lower the cost the lower the rating. By the way 160 minutes isn't
as bad as it sounds. A 25 amp load is very high. Even a furnace will only
draw 1/2 that. A typical light bulb draws .5 amps per hour. So turn on
5 light bulbs (2.5A) and you can leave them on for hours.
Leave one light on and you can go 5.5 days.
Hope this helps more than confuses.
Charlie