Battery Testing

[willbur]

Greetings-
tested an AGM battery rated @ 800 CCA (referenced @ 0F) with a Midtronics conductance tester. It showed 1030 CCA. Great? However the temp was 72F. Correcting for this temp yields a calculated 1250 CCA . Looks like this battery is short about 220 CCA.- almost 18% lower. So..which value should I use in evaluating this battery?

 

[The_Jeff]

I don't understand your issue.

Is this a brand new battery? They usually measure "over" and it's by about the factor you've found.

Is the tester in AGM mode? They're a little different inside.

Does the tester have an IR port so it can get a battery temp? Then it does an automatic internal correction.

 

[willbur]

Originally Posted by eljefino
I don't understand your issue.

Is this a brand new battery? They usually measure "over" and it's by about the factor you've found.

Is the tester in AGM mode? They're a little different inside.

Does the tester have an IR port so it can get a battery temp? Then it does an automatic internal correction.


Thank you-
it's 1 year old but only about 800 miles and maybe 10 starts on my garage queen. I use a trickle charger on it once a week and it charges up to 12.8+ volts and turns off. I'm trying to get the seller to honor the 3 year free replacement warranty. The battery seems to discharge very quickly in the car. Parasitic draw is 16 milliamps (up 25 is acceptable and the FSM specs 25-40).The store is using the CCA to says its not the battery but the car drawing down the battery. Don't know if the tester was set on AGM mode and if it corrects for temp. I took whatever they said as bring representative. Since my initial post, I back calculated the CCA at 0F as being 660, not the stated 800. This is a premium upsized battery, not a discount store 24 month special

 

[The_Jeff]

Typically you need to be under 50% of rated CCA to flunk for battery warranty.

The store's tester at 72' does the math to compensate for temperature, so a CCA rating (named CCA) is authentic.

 

[willbur]

I
Originally Posted by eljefino
Typically you need to be under 50% of rated CCA to flunk for battery warranty.

The store's tester at 72' does the math to compensate for temperature, so a CCA rating (named CCA) is authentic.


I called the store. They did not correct for temp. I also mentioned static open circuit voltage indicated a 20 % decrease in SOC and the 18% decrease in cca corroborates my story. They then agreed to a free like replacement.