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Does the battery need replacing?


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Came back to my car (2008 is250 SEL) last night after a meal out, but the car wouldn't start, strange thing was, had the green light on the ignition button, but nothing else, managed to jump start it and get it home, tried it this morning and it started no problem, should I replace the Battery? Or is it an alternator problem? I replaced the Battery when I first got the car, that was just under 3 years ago, I still have 1 month left on the guarantee on this particular Battery, so not sure whether to just get it replaced? Thanks

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If it started easily this am there's nothing wrong with the Battery. Last night some volts were getting through to give you ignition lights, but I guess the connections weren't allowing enough current to flow to turn the starter motor/engine.

My guess from here would be that your Battery connections need tightening up. The terminals are conical and the clamps can slide up and cause a poor connection. Try tapping the clamps down very lightly with a very small hammer as you tighten the clamps - very carefully!

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Hi Paul. Yes it sounds  like a dodgy Battery connection. Take both connectors off, give them a good clean and the Battery connection posts. Apply a light coating of grease and attach the wires back making sure they are fully 'home' and done up tight.

If you haveca volt meter then you can check you alternator by measuring the voltage of your Battery which should be around 12.5 volts. Start your car and have someone hild the revs at around 2 thousand revs and measure the Battery voltage again. It should be about 14.5 volts. If it reads the same or close to when the engine is off then it looks like a duff alternator.

Let us know how you get on.

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You shouldn't really use ordinary (lithium, etc) grease on Battery terminals - I think because it may have an adverse effect on the Battery case. I have and use some Holts' No-crode from years ago - nowadays you can get specific Battery terminal grease from Liqui-Moly or use Vaseline or other petroleum jelly. 

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Normal grease has been used in my families cars for the past 60 years with absolutely no adverse effects. 

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6 hours ago, johnatg said:

If it started easily this am there's nothing wrong with the battery. Last night some volts were getting through to give you ignition lights, but I guess the connections weren't allowing enough current to flow to turn the starter motor/engine.

My guess from here would be that your battery connections need tightening up. The terminals are conical and the clamps can slide up and cause a poor connection. Try tapping the clamps down very lightly with a very small hammer as you tighten the clamps - very carefully!

Thanks for the advice, trying to do all of that in between the showers 😀

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3 hours ago, Mr Vlad said:

Hi Paul. Yes it sounds  like a dodgy battery connection. Take both connectors off, give them a good clean and the battery connection posts. Apply a light coating of grease and attach the wires back making sure they are fully 'home' and done up tight.

If you haveca volt meter then you can check you alternator by measuring the voltage of your battery which should be around 12.5 volts. Start your car and have someone hild the revs at around 2 thousand revs and measure the battery voltage again. It should be about 14.5 volts. If it reads the same or close to when the engine is off then it looks like a duff alternator.

Let us know how you get on.

I have a mate who has a volt meter, will get him to check the Battery for me. Thanks for the reply

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  • 2 weeks later...
On 8/8/2021 at 12:34 PM, Mr Vlad said:

Hi Paul. Yes it sounds  like a dodgy battery connection. Take both connectors off, give them a good clean and the battery connection posts. Apply a light coating of grease and attach the wires back making sure they are fully 'home' and done up tight.

If you haveca volt meter then you can check you alternator by measuring the voltage of your battery which should be around 12.5 volts. Start your car and have someone hild the revs at around 2 thousand revs and measure the battery voltage again. It should be about 14.5 volts. If it reads the same or close to when the engine is off then it looks like a duff alternator.

Let us know how you get on.

This morning check Battery using volt meter was showing 9v it's original Battery surly should last more then 3 yrs. Struggle to start then show 12.5 .when started showing over 14v . gonna charge overnight hopefully fix it done on my taxi still working

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Hi Paul. What's the latest with your Battery problem? It's been a few weeks. 

Hi Iftikhar. You say you measured the voltage of your Battery this morning and it read 9 volts. Then after a few tries trying to start your car it read 12.5 volts. Then when it started it showed 14 volts. 

It's confusing that initially it showed 9 volts and you struggled to start your car. Then a reading of 12.5 volts? Surely if you cranked the engine over on a 9 volt Battery it would have read less than 9 volts unless your alternator is superb at charging a Battery really quickly. One thing for sure your alternator is running perfectly. As for your Battery you've probably got a power drain somewhere. 

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10 hours ago, Mr Vlad said:

Hi Paul. What's the latest with your battery problem? It's been a few weeks. 

Hi Iftikhar. You say you measured the voltage of your battery this morning and it read 9 volts. Then after a few tries trying to start your car it read 12.5 volts. Then when it started it showed 14 volts. 

It's confusing that initially it showed 9 volts and you struggled to start your car. Then a reading of 12.5 volts? Surely if you cranked the engine over on a 9 volt battery it would have read less than 9 volts unless your alternator is superb at charging a battery really quickly. One thing for sure your alternator is running perfectly. As for your battery you've probably got a power drain somewhere. 

Sorry for the late response, I had my car serviced yesterday, and while it was being serviced, I asked the mechanic to do voltage and drop test on the Battery, turns out the alternator is fine, but the drop was reading that the Battery is weak, he thinks that one of the cells is faulty. Luckily the Battery is still under warranty, runs out on the 16th Sept this year. 

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A few days ago I noticed that the starter turned slower when starting the car, but it would start no problem.

Checked the built in service menu and alternator would charge 14.1-3, which is fine as voltage should not drop below 13.6.

I had the Battery measured and it was on full charge, however, the starting power was at 51% - from 70 amps to 35. Decided I would replace it the next day (today) and the Battery died the same night. Mind you, I had lights and stereo but the car would not start at all. Replaced the Battery today and everything is good.

So if you have any doubts in the Battery charge, first check the service menu (if using the nav unit). Hold the Info button and flash parking lights on and off 4 times. From memory, you need to go to Nav settings - vehicle sensors and you can see if the alternator charge is above 13.6V.

If no issues there, have the Battery checked as it could be fully charged, but its starting power could be low.

 

 

 

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  • 2 weeks later...

 got it checked from garage was showing low charge so was gonna charge overnight was told take on long run should fix it.so went Chessington M25 seems to be ok now start on button. Strange . rather than replace should charge overnight first as it fixes cells .done on taxi it's 1 yr still same Battery

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