Club 80-90 Forums

Im guessing this is electrical but it could be mechanical so sorry if posting in the wrong section..

basically the alternator is showing a charge of 12.3 and the battery is showing 12.3, the van will jump fine but even after running it for 20mins down the road
as soon as I go to start it again it turns slightly but nothing happens.. I'm wondering if the alternator is charging properly or if I need a new alternator ?

I have posted the pic below and I can see one of my black wires which is connected below the alternator is loose but I cant figure out where it needs to go (is it the earth lead? - if so where do I attach it? ) or is it even causing the problem / or has nothing to do with it ...any help again would be really appreciated..

Battery should be about 12.6, if you have an old battery replace it. The average life span of a battery is about 5 or 6 years. Dont bother trying to charge a dying battery, just get a new one then see if there is another problem that needs looking into.

multisi wrote:Battery should be about 12.6, if you have an old battery replace it. The average life span of a battery is about 5 or 6 years. Dont bother trying to charge a dying battery, just get a new one then see if there is another problem that needs looking into.

ye I guess so but its only 3 years old, is that old then?

If the alternator is reading 12.3V with the engine running, then it is not working and hence not charging the battery, it should read between 13.8V and 14.4V.
If is a non standard engine then some alternators are rubber mounted and need an earth cable.

bigherb wrote:If the alternator is reading 12.3V with the engine running, then it is not working and hence not charging the battery, it should read between 13.8V and 14.4V.
If is a non standard engine then some alternators are rubber mounted and need an earth cable.

sorry I should of said this is the reading after the engine had stopped..I'll check it when Ive jumped it again and give the reading

If you want a bit of light reading on the subject put alternator voltage regulator in the search box(top right).Plenty to search through. I had a similar problem-turned out to be a worn regulator on the alternator-a five minute job to replace.
David

jrt wrote:If you want a bit of light reading on the subject put alternator voltage regulator in the search box(top right).Plenty to search through. I had a similar problem-turned out to be a worn regulator on the alternator-a five minute job to replace.
David

aha, I see, ok I'll have a read and then I'll try and locate it as its a vw passat TD lump in there atm...

Battery voltage is not a good measure of battery health.
A partially sulphated battery can show a good voltage but not start your van.

as suggested above, check voltage with the engine running, if it's less than 13.8v suspect your alternator or cables.
Otherwise suspect your battery, age makes no difference if it's been abused.

after that, the next culprit could be your starter motor or it's bush.
Good luck.

bigbadbob76 wrote:Battery voltage is not a good measure of battery health.
A partially sulphated battery can show a good voltage but not start your van.

as suggested above, check voltage with the engine running, if it's less than 13.8v suspect your alternator or cables.
Otherwise suspect your battery, age makes no difference if it's been abused.

after that, the next culprit could be your starter motor or it's bush.
Good luck.

ok I have more ... both alternator and battery show 14.1 when running - it then switched off the engine and immediately turned it and it started, I then turn it off and waited 5 secs went to turn it and it did not turn for long then completely went dead.... so it must be the starter motor? or a brush..not being naive well actually I am - where is the starter motor please? thanks ..

Your alternator should give the battery 14.6V when running, it isn't and that's why the starter is struggling to turn the engine over with the weakened battery. However your battery will be fine. Take the opportunity to put it on charge overnight, as it should offer 12.6V standing. As said above, probably worn regulator on your alternator to change.


Sent from my iPhone using Tapatalk

T25Bluealloy wrote: ok I have more ... both alternator and battery show 14.1 when running - it then switched off the engine and immediately turned it and it started, I then turn it off and waited 5 secs went to turn it and it did not turn for long then completely went dead.... so it must be the starter motor? or a brush..not being naive well actually I am - where is the starter motor please? thanks ..

It is most likely a faulty battery, if the engine turns and starts on a jump start you are eliminating the starter motor.

DoubleOSeven wrote:Your alternator should give the battery 14.6V when running, it isn't and that's why the starter is struggling to turn the engine over with the weakened battery. However your battery will be fine. Take the opportunity to put it on charge overnight, as it should offer 12.6V standing. As said above, probably worn regulator on your alternator to change.


Sent from my iPhone using Tapatalk

excellent thanks doubleoseven ok so now I need to charge the battery, ok no problem..but im also looking for an alternator regulator for a vw passat engine, which I believe looks like the below image, however I cant seem to find anything like this, i know my engine is on its side so would it be underneath? sorry for the naivety but im struggling here..

Reckon it's your battery.
Wouldn't do any harm to replace the regulator for a 14.5v one but 14.1 is acceptable. IMHO.

bigbadbob76 wrote:Reckon it's your battery.
Wouldn't do any harm to replace the regulator for a 14.5v one but 14.1 is acceptable. IMHO.

ok well I know where the regulator is now (in the alternator) and so I'll try that first and then maybe a new battery, thanks alot guys!

Also, have a look at fitting a 'hot start relay' - should only cost a few quid and about 20mins to fit. It basically takes the current to spin the starter straight from the battery rather than routing it through the ignition switch wiring


Sent from my iPhone using Tapatalk