Quote:
Originally Posted by bollwerk
The Reserve Capacity (RC) looks the same on both batteries, so all you should need to do is just use Carly to tell your car you have a new battery. No other settings should need to be changed. (I don't yet have Carly, so I'm not sure how the process works)
I'm not sure why the Ah values are different though. Same RC should also mean same Ah, according to things I've read.
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I'm not sure how you're not sure why the AH values are different. They aren't listed on the replacement batt. Hence the question.
The RC is a way of expressing Ah, but by measuring at a much higher current than traditional Ah ratings. So it isn't necessary exactly the same, but certainly close enough to assume the battery can be registered without having to change the Ah rating.
For you geeks, the RC is the supposed to represent the amount of time you can drive with no alternator. It is a count of minutes the battery will run with a fixed 20A draw until it dies (the battery label says 20Ah, that's wrong haha).
The Ah rating is how many... amperehours you can pull at a constant rate until the battery is dead, typically over a period of 20hr. Or C/20 rate. Or 0.05C, for you drone pilots.
RC and Ah are both measures of capacity, both are "bigger is better", but one measurement method takes 2 hours, and the other takes 20 hours. One, the unit of measure is minutes, the other, Ah. Battery design can be tweaked to perform a little better or a little worse to trade off one stat for an improvement in the other. Same is true of RC vs CCA.
BTW this was all from memory so I might have something slightly off.
Edit: actually RC is a 25 amp rate, not 20. So I'm not sure what the "20 Ah" typo is even supposed to read. It should read either "@ 25A" or maybe they are fudging the numbers and it's supposed to be " @ 20hr" meaning they stretched the test from 140 minutes to 20 hours... hmm.