When I got back from my holiday, the car battery was flat (not that I didn't say to disconnect the battery). It was flattened by the immobiliser and radio at a guess.
How can I tell if it's going to let me down next winter?
See how it goes on on a daily basis. If, as the Autumn nights get cooler, it shows signs of struggling to start the car in the morning change it then.
If it hasn't survived your holiday of what, 2 or 3 weeks?, I would put money on it failing at the first frost, or soon after.
Steve
4 weeks. My dad, in his brilliance, also decided to start the car and turn it off half way through the holiday which will hardly have helped the state of charge. It's a GSF battery though, so you can expeect it to be shit (the last one was, had to be replaced under guarantee). Next time it's bosch.
Re-charge it fully and get a load test done. Most places that sell batteries have a flash electronic tester these days. But it will also depend on age. Anywhere near 5 years is about the limit.
Next time get a diesel battery. Bit more expensive but won't let you down.
Alex
The original BMW branded battery in my 528 just made the 3 year car warranty before dying without warning. The E39 has an odd shaped battery and the only one I could find that would fit was a Bosch - and it looked identical to the BMW one in every way apart from the badge. So I've guessed it's OEM. It has, however, well and truly passed the 3 year old stage.
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