Battery Failure

No (don't think so!) - a fairly ordinary Yuasa 065 with cold cranking around 500/600 A.

Replaced with a Yuasa 075 with slightly higher cold cranking capacity.

The testing device the RAC man used did display something like "Bad battery - replace" but initially it had looked OK.

Not sure quite what the voltage display meant - with one of the RAC testers would that be entirely off-load or does it apply an internal load?

Oh gawd! I would have to search my receipts file, I know I got one for the battery, but the car has gone... Thanks for the tip.

That isn't the point, to nick a battery is naughty, to announce in in a forum is careless. ;-)

The testers check voltage off load voltage under load minimally plus the device can check the charging capacity drain and even the internal resistance of the battery

Percent remaining life?

8:30am start car drive to work 5:00pm start car drive home 7:00pm start car drive to swimming pool 10:00pm failed to crank had to get a jump start. Lights etc still worked. Put on charge overnight 7:00 am next failed to crank. Robbed other car.

Still has 12.8V. And hydrometer shows all cells are fully charged.

As far as I can tell it went from being OK to dead in one trip. This was about April this year. The battery has a sticker on it says "Recharge if not used by Nov 2004"

Was an expensive brand.

That's a very common way for a battery to fail these days.

Cars start so easily, and have such efficient charging systems, that a battery with very little spare capacity will work right up until it dies.

A full test would have predicted the remaining likely capacity, although obviously would not show the possibility of a failure due to breakage of an internal link, or a plate collapse. (Rare events these days.) Off-load voltage and specific gravity only tell you the state of charge, which is not what is needed.

Your battery probably didn't go from OK to dead; over its life, its capacity reduced. IOW, its final rating in terms of Ah and its CCA would have only been a fraction of what it was when new.

Chris

Usually seen on the first cold day of the autumn;!. As what most anything chemical temperature has a lot of do with it.....

Maybe it didn't. But the old one had been installed on 13/06/2014 and, to the best of my knowledge, worked reliably from then until last Saturday. That is, no warning lights, failures to start or other signs of things going wrong. And I am virtually the only person who ever drives the vehicle.