Flat battery

[Scorpio7771]

You need to charge it properly first, 12.31V after a long drive is not good, there is just no way such a battery passed all the tests it is said to have passed, problem is convincing AA of your tests, it would be better to take it to a battery place for proper testing and a report to show to the AA.

Yep, best to go the proper test route with a report

I read this another forum. A guy had a similar problem and it turned out to be a bad cell. Even with the bad cell, the battery was tested over and over again and passed 100% by the manufacturer.

Thanks, would ask them to check for bad cells.

 

[Moto Guzzi]

To make a long story short a new battery may past tests/start a car ok, but if the charge is removed and the voltage drop fast, faster than good new ones, theres already something off with it, I find this out by buying two new batteries fully charged after I calibtated a generator cutoff switch delay to prevent the motor from restarting as contacts close at full charge and motor run again, I did this on two of my personal car batteries. Putting in the new ones, it took me a day to figure this out, they both failed a maximum load test new at dealer, but they did start a car well, both replaced, the replacements were ok, voltage not dropping too fast between 14.5 to 12.5V, so make sure your new battery is tested properly before walking off.