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V90 draining of battery

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Old Nov 18th, 2019, 14:34   #11
ns1234567
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......sorry one more thing - yes the belt is tight (smoke on the water - original key G minor !)
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Old Nov 18th, 2019, 15:13   #12
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Thanks Dave

Interestingly the charging light (on the dash) doesn't come back on under load at night etc - not even a glimmer - so if IT is working I assume the alternator is charging but low as you point out.Is it faulty would you say (it has to be the original) - and is it worth attempting the modification to boost it's output voltage..?
There may also of course still be a drain - problems sort of started around the time the central locking failed (except for the key operating the driver's door and tailgate)

Very grateful once again for your time

nick
You've obviously got more than one problem Nick, let's set the central locking to one side for now and concentrate on the alternator as i have a feeling the battery voltage may be too low to operate the central locking but that's for later on.

Do you have any jump leads at all and if so are they known to be good?

If yes to both, get your DMM set on DC Volts, 20V range and start the car from cold and check the charging voltage, should be 14.4V and the idle speed should be slightly higher than when hot due to cold start maps in the fuel ECU, probablt around 1000-1200rpm.

If the voltage isn't around 14.4V, get your jump lead (just one) and clip it onto the alternator casing and the other end to the battery -ve/earth terminal. Now check the voltage again. If it has increased, move the clip on the alternator to the engine block and check again, if it has dropped this time it points to the earth link on the alternator. THis goes between the alternator casing aka bracket and the mounting bracket because most Volvo alternators are mounted on rubber bushes to help eliminate vibration.

To double-check this, leave the clip on the engine block and move the one from the battery -ve terminal to the alternator casing and check the voltage again. If it has gone back up to around 14.0-14.4V, it confirms the alternator earth link.

There are several further tests but this is the first you need to do, if the alternator earth link is faulty, nothing else will make sense.
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Old Nov 18th, 2019, 16:17   #13
ns1234567
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Dave - very clear thank you

Without starting battery reads 12.36
Starting from cold (and rpm higher as a result) 13.56
Then clip from battery -ve to alt casing - no difference
clip to engine block - again no change
and clip from block to alt casing - no change

warmed up voltage 13.62

I could however be a bit rubbish at clipping ..... also just noticed a green disc on the battery which indicates it's "good" - could have read needs charging or needs replacing.

Any thoughts..?
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Old Nov 18th, 2019, 17:01   #14
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The voltage before you start isn't bad Nick :



That's about 75% charged but more worrying is the lack of output from the alternator. That's why you have a green disc showing in the "magic eye", it's only a very simple hydrometer with three colours that change according to a float position in the electrolyte in the battery.

Do you know if you have the Bosch or Nippo-Denso unit in your car? The Nippon-Denso looks like this :



The Bosch should have a green label on somewhere giving the model number (usually 0 120 abc xyz) which is 10 digits long. Should also have the output spec eg 14V 100A or similar. It also looks a bit different to the Denso unit.

Meanwhile another test you could do is similar but instead of clipping from the alternator case to battery -ve, go from the main output terminal to battery +ve but you need to be careful to not short the lead to earth whether that's the alternator case, body, engine block etc. Again you're looking for an increase in voltage when the extra lead is in use.
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Old Nov 18th, 2019, 19:55   #15
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Thanks again Dave - much appreciated

Will have to look again in the daylight for the labels on the alternator and also the other check with the jump lead - worst case scenario new alternator..?

Best wishes

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Old Nov 18th, 2019, 20:14   #16
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Thanks again Dave - much appreciated

Will have to look again in the daylight for the labels on the alternator and also the other check with the jump lead - worst case scenario new alternator..?

Best wishes

nick
You're welcome Nick, hopefully it's fixable but to be certain it is we need to find out if it's a vehicle or alternator fault first. No good throwing another alternator at it if it's a wiring fault on the car!
Also because of slightly (but important!) different repair procedures, we need to know the make of the alternator, Then we should be able to formulate a plan to fix it.
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Old Nov 18th, 2019, 20:50   #17
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Great OK - will post as soon as I have the info on the alternator

All the best

nick
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Old Nov 19th, 2019, 11:22   #18
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Morning' Dave

Yes it's a Bosch alright - 14v and 50-100A
Part no 0128 500 006

Volvo part no 9447864

Struggled again to start this morning (the car - not me) - one other thing ....in Feb when it was really cold here - the starter motor wouldn't turn - RAC bless them took it off tried to get a new replacement - couldn't and in the end freed up the original motor and put it back on - would it be possible that although we do have electrical issues the old starter motor is asking just a little too much..? (I do now have a "not new" replacement motor as yet not fitted )

Thanks again for your time - I'll be out until late afternoon but look forward to hearing from you

Best wishes

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Old Nov 19th, 2019, 12:07   #19
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Sorry Dave (again)

That Bosch part no might read

0123 500 006
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Old Nov 19th, 2019, 14:47   #20
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Right second time Nick! It's 0 123 500 006, the part i strongly suspect you need to solve your probelsm is a VRG46401 :

https://www.ebay.co.uk/itm/NEW-VOLTA...W/301954011350

This is mounted on the back of the alternator and secured by two screws. Undo them and pop it out, release the clip from the brushes on the new one and insert it at an angle so the brushes contact the two copper slip rings and ease it in reducing the angle as you go so it eventually sits square. Hold it there with one thumb while you fit one screw fingertight, swap thumbs and fit the other then finish tigethening them.

While you have the voltage regulator out, have a look at the slip rings and check they're not worn away to nothing, rotating the alternator pulley by hand while you check the slip rings. Sometimes a small mirror (like a dentists mirror) is useful depending on how your alternator is fitted.

Just been looking at other photos of that particular alternator and it seems there's a plastic cover on the back that you'll have to remove first :



Looks like it's just the 3 Pozidriv screws near the centre but you may have to remove the battery and field leads too. Looking deeper into the construction, it's not the "conventional" Bosch alternator which may well work in your favour as you should be able to see the slip rings much easier and also have the space to thread some emery cloth through and clean up the slip rings - DO NOT USE sandpaper!

While the reg is out, clean the points where it mounts on the alternator bracket too.

I'd suggest a "dummy run" of replacing the voltage reg before you order one as if your slip rings are worn excessively then it's likely to be cheaper to get a reconditioned alternator.

As for your starter, i'd suggest fitting the replacement ASAP. Before you do however, have a look at this pic :



See the two Pozidriv screws that hold that cap on in the middle? Remove those and the cap, you should see a phosphor bronze bush, drop a little engine oil on this and let it soak - just a few drops, you don't want it to get further in. At the other end of the starter, you'll see another phosphor bronze bush in the end of the nose of the starter - a few drops of engine oil on here too.
Refit the cap and screws anf fit it to the car.
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