Battery Capacity

Submitted: Tuesday, Feb 19, 2002 at 01:00
ThreadID: 769 Views:1796 Replies:3 FollowUps:4
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Could anyone assist with a formula for converting battery capacity from cold crank amps [cca]to amp hours [a/h]
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Reply By: Dennis N - Tuesday, Feb 19, 2002 at 01:00

Tuesday, Feb 19, 2002 at 01:00
Mark,

Dug this formula up using Google [wanted to know myself seeing you asked]

Cam from a University of Hawaii electronics website. hope it is of use:

Many batteries today are rated in CCA or RC. CCA is Cold Cranking Amps. CCA is approximately equal to the RC of a battery times five. [1000 CCA is about 190 RC]. RC is Reserve Capacity. You can convert RC to amp/hours by the following formula:

Amp/Hours = (Reserve Capacity / 2) plus 16
AnswerID: 2148

Follow Up By: Rich - Wednesday, Feb 20, 2002 at 01:00

Wednesday, Feb 20, 2002 at 01:00
Dennis
I would like to THANK YOU!

I searched for nearly an hour for this exact info. (using Google !!) Perhaps my wording was incorrect?

Do you still have the URL?

My problems are solved with just this inforamtion.

Cheers
Rich
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FollowupID: 755

Follow Up By: Mark - Wednesday, Feb 20, 2002 at 01:00

Wednesday, Feb 20, 2002 at 01:00
Many thanks to all those who responded to my question.
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Follow Up By: Dennis N - Wednesday, Feb 20, 2002 at 01:00

Wednesday, Feb 20, 2002 at 01:00
Mark, I Dont know too much about the subject but I got the formula from the following page:
http://www.chem.hawaii.edu/uham/bat.html
Hope this helps. The search query I used was "formula for converting cold crank amps to amp hours" - it was the first item on the page.
regards
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Reply By: Steve - Wednesday, Feb 20, 2002 at 01:00

Wednesday, Feb 20, 2002 at 01:00
Beware using the formula too literally. It is for standard construction batteries. Note that there are significant differences in the construction of Deep cycle to starting batteries. For example a standard 75 amp/hour starting battery may have 1000CCA (if your starting a landcruiser ;). However, a deep cycle 75 amp battery may only be able to deliver 500CCA...as it is not meant for high amp starting. Best way is to check the labels or web sites.
AnswerID: 2151

Reply By: porl - Wednesday, Feb 20, 2002 at 01:00

Wednesday, Feb 20, 2002 at 01:00
As per the last response - the formula may work for certain types of batteries but deep cycle batteries are fundamentally different in construction to starting batteries and for that very reason they are measured in CCA and not RC. An good example of the last reply is my deep cycle yellow top optima - it has a rating of 65ah but at 0 degrees centrigrade can put out from memory something like 950CCA - which certainly does not fit the formula proposed - but that of course is perhaps because the optima is not a wet celled battery. etc etc. Also, don't use a starting battery as a deep cycle battery to draw down to its DOD (depth of discharge) or you will get a fraction of its expected lifespan.
AnswerID: 2152

Follow Up By: Taj - Wednesday, Feb 20, 2002 at 01:00

Wednesday, Feb 20, 2002 at 01:00
Sorry to but in on your thread Mark, I have an aux batt. Yuasa 57 with a CCA 445 and an RC 96 , in layman terms is this a small/large capacity batt (no mention of deep cycle etc on batt.)The reason I ask is that I am not happy with the perormance running my fridge etc. for more than a day and a bit without having to run the engine. Thanks Taj
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