It actually is not conclusive. My battery that could start my 3.0 at 0°F and tested 550 CCA on an old school resistive tester couldn't run an iPhone for 30 minutes nor the hszzards for 8 minutes and start the car after.

All I can figure is that somehow the plates were covered in such a way it affected only capacity not current or voltage. Basically rather than having an 800A,100AH battery it was a 550A, 1AH battery (could supply 200A for a start a couple times but the capacity being literally about 1AH means I could crank a few times at best or run the iPhone charger maybe 20 minutes (30 and I couldn't start the car)

That all said: normally bc is correct, a load test *should* by all means give you a definitive answer about the battery condition, but only a long term load test (eg pull 10A for half a day) will test the battery fully. Nobody ever performs that test but it really should be done occasionally. An 80AH battery should be able to run a 1A load for 80 hours, and a 10A load for maybe 6A for 10-11 hours (internal resistance costs you some storage the higher the draw)

My dad has a 100A load tester I think it might have a lower setting I'll have to check.

+1 on the upgrade a bit concept, especially if you live in a cold climate. There's a very good reason nobody talks about the hot cranking current

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)