Battery!

[KeithJG]

I am off to Olly`s early tomorrow to have my valve block in the 7g fitted.

Previous searches for the answer to my problems included the battery, it was the original so about 9yrs old and was giving 12.03v after a run of 50mls 12.05v.

I don`t use the motor that much so decided on a new MB Varta battery which Olly fitted a couple of weeks ago.

I did notice that my clock on the dash was losing 15mins every week prior to fitting!

But now with the new battery it is keeping time ok exactly.

Why i mention this is because upon putting a meter to the new battery it only reads 12.98v.....but enough to make the clock now accurate.

 

[John]

When I had a duff (but still working somewhat) alternator, I was getting that sort of voltage when switched off.

Might be worth seeing what the charge is when running.

 

[KeithJG]

Just an update.

Had the Valve Body in the 7g done at Ollys yesterday and the STAR readout showed Battery a whopping 14.0v so after a couple of good runs the alternator has done it`s job.

But nevertheless my readings with a difference of just 1v made the clock lose time.

Now at +2v i expect time will fly...lol

 

[Aero]

Just an update. Had the Valve Body in the 7g done at Ollys yesterday and the STAR readout showed Battery a whopping 14.0v so after a couple of good runs the alternator has done it`s job. But nevertheless my readings with a difference of just 1v made the clock lose time. Now at +2v i expect time will fly...lol

Hi KeithJG,

Side topic to this thread I know but what problems did you have on gear changes before the valve body fix? Was a new body or recon one? I'm contemplating having this done hence my query. If you don't mind me asking what was the general cost (rough is fine)?

 

[camerafodder]

You don't say whether your battery readings are with the engine running or not. A charging healthy battery will show around 14.4v. This will stay high for a short while after the engine is switched off but at rest a healthy fully charged battery will show a quiescent voltage of around 12.6v. If you have 'key-off' loads then this value will fall over time in proportion to the loads until the car is started again.

 

[KeithJG]

Hi KeithJG,

Side topic to this thread I know but what problems did you have on gear changes before the valve body fix? Was a new body or recon one? I'm contemplating having this done hence my query. If you don't mind me asking what was the general cost (rough is fine)?

@camerafodder.......engine was stopped and STAR was plugged in = 14.00v

..............................................

Hi Aero....look in the engine section.

 

[190]

The temporary high voltage when the engine is first turned off is due to something called surface charge. It occurs with all lead acid batteries and dissipates after a few hours or possibly quicker in the case of an MB where there are current draws until the car goes to sleep. It's worth knowing about as it will give a false indication of the state of charge of the battery if the voltage is read soon after an engine stop or removal of a battery charger. I wait a few hours or over night before taking a reading of 12.7 volts on the standard silver low maintenance battery. AGM batteries should read higher - something in the region of 12.9 volts.