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JohnP

Keep losing time.

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I have a BMW 535d e61. The clock keeps on resetting to 00:00 and if not driven for more than a day the date stays on the day the time reset. I've read plenty of feeds about it being a sign of a poor battery that on its way out but I've had the battery checked and it came back good also the Volt readings in the secret menu are good 12.6 at rest and straight up to 14.9 when running. Is there anything else that causes the time loss other than a week battery?

Many thanks.

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My battery tested fine, but would keep doing this. It did turn out to be the battery - I discovered this when I came to the car one day, jumped in, put the key in and got 'click' from the starter motor and that was it. New battery in and no problems since.

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Mines be doing this for over a year and one thing it's never done is struggle to start, even when it's really cold. So you think it could still be the battery even when it's able to do that?

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From what I can gather from reading on here, the clock reset etc happens when you put the key in and the battery voltage drops with things turning on. And dropping further as the starter cranks. All available power is sent to the starter to turn the engine over, which causes the memory loss. It would be worth getting the battery tested as the car is being started to see what the voltage is dropping to. The battery may not be able to cope with the huge power draw when the engine cranks over. If you've got a friend with a 5 series or a car with a similar sized good battery with no problems I'd swap them over for a day or two and then try the same scenario again. It's unusual with it going on for over a year and evidently not getting any worse. If the problem is cured, battery is the answer. If not then the problem probably lies elsewhere. Where abouts are you located? It's a 10 minute job to swap the batteries over.

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From what I can gather from reading on here, the clock reset etc happens when you put the key in and the battery voltage drops with things turning on. And dropping further as the starter cranks. All available power is sent to the starter to turn the engine over, which causes the memory loss. It would be worth getting the battery tested as the car is being started to see what the voltage is dropping to. The battery may not be able to cope with the huge power draw when the engine cranks over. If you've got a friend with a 5 series or a car with a similar sized good battery with no problems I'd swap them over for a day or two and then try the same scenario again. It's unusual with it going on for over a year and evidently not getting any worse. If the problem is cured, battery is the answer. If not then the problem probably lies elsewhere. Where abouts are you located? It's a 10 minute job to swap the batteries over.

Thanks pal. I've had the battery tested at Halfords and it said it was good. I'm in Sutton Coldfield near Birmingham.

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Most likely faulty IBS if not short trips and frequent stop / starts. Have the codes read and what year is the car?

Need to buy a code reader. It's 2006.

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I think you have one weak cell in the battery. I've seen this before. If you monitor the voltage at start up you'll see a huge dip where the cell voltage collapses. That's what resets the time.

 

The battery will keep going for a bit then completely fail instantly when that cell totally gives up.

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I think you have one weak cell in the battery. I've seen this before. If you monitor the voltage at start up you'll see a huge dip where the cell voltage collapses. That's what resets the time.

 

The battery will keep going for a bit then completely fail instantly when that cell totally gives up.

So can a week cell be undetected when tested?

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After 2-3 weeks of zero activity my car reset it's clock (not date) when i started it. Along with a rear suspension height failure.

All was fine after i restarted though

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After 2-3 weeks of zero activity my car reset it's clock (not date) when i started it. Along with a rear suspension height failure.

All was fine after i restarted though

Sometimes my radio won't turn on and the fans won't blow very hard.

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1 hour ago, Blobby said:

After 2-3 weeks of zero activity my car reset it's clock (not date) when i started it. Along with a rear suspension height failure.

All was fine after i restarted though

 

Probably end up buying a new battery if you don't take the beast out. Noisy lifters are a sign of senility :D

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