RS4 seems to have died

[chris_marshall]

Evening all, this is a post on behalf of my old man. Went to use his B5 today, switched on the ignition lights came on but not enough power to start it (must stress this is a daily driver so hasn't been left). Anyway, wheeled it out the garage and jumped it off my car ran it for 15 mins and switched it off, then went to use it later and the same thing happened. Any idea as it just seems a bit out the blue. No warning lights up either

 

[adamss24]

How old is the battery ? It might need a new one and i would check if there is healthy charge from the alternator.

 

[MECANICA98]

is it ok

 

[chris_marshall]

Didnt get a chance to check, but jumped it off mine again and then disconnected but kept it running, and the volt gauge was hovering just under the 12v mark slightly rising when the throttles blipped

 

[graemep]

Sounds like the alternator might be on the way out - the voltage gauge should be reading higher than that

 

[audicruiser]

When running and charging the battery the alternator normally kicks out around 14 volts....

 

[colicabcadam]

based on what you have said, it'll either be an alternator or regulator/rectifier problem or wiring problem between those components.


if you charge the battery up from the mains, you'll prob be ok for a while, basically, the cars electrics are not providing enough current to run the car and charge the battery, in fact, it's actually providing less than the car uses, hence the battery goes dead after a while.

i had the same problem on my ducati 748

 

[Marc1]

How do you check the alternator is charging the battery? I have the same problem at the moment

 

[colicabcadam]

How do you check the alternator is charging the battery? I have the same problem at the moment

buy a multi meter such as Draper 60792 Digital Multimeter With Backlight: Amazon.co.uk: DIY & Tools

check the battery voltage when the car is not running (a good battery should read around 12.6) then check it again with the car running (it should produde around 14.6v (i do not know the exact figure)

 

[PetrolDave]

After startup the battery voltage should be less than 14.5V and drop fairly rapidly as the alternator re-fills the battery.

If it stays down at 11 or 12V then the alternator isn't charging, if it's over 14.5V then the alternator regulator isn't working properly.

If the voltage drops rapidly to 11 or 12V when you turn the engine off then the battery isn't holding charge, it should stay up over 13V.