Volvo Owners Club Forum - View Single Post

oragex · Jul 10th, 2019, 16:48

Do you have one of these ? https://www.youtube.com/watch?v=IVDHzTkjHlc

It helps because the alternator output voltage varies depending if the battery needs charged or not. Basically, at start up the battery needs charged a little to top it up (i.e. until it reaches some 12.7-12.8V) so the alternator puts out some 14.5v for a few minutes. Then, once the battery has been fully charged, the alternator voltage drops to some 13.5v to power the various electrical car systems.

Now, the above is the ideal operation when the battery is in top shape.

However if the battery is old, it gets very slow to charge so you may see the alternator putting out 14.5v for long time while driving.

On the other side, if the alternator puts out always only 13.5v, even when right after starting the engine, then there is one or more problems:
1. the battery cannot get fully charged, which will damage it in the long term. 2. the battery may be already very worn and no longer accept a full charge so the alternator doesn't even try to charge it any longer.
3. the alternator may not be the correct one for the car and may not put out the correct voltage to properly charge the battery. For example, in these cars there are two different regulators: one for 2001-2004 and another one for 2005-2009. You need to have the correct one for your car year, or the alternator will not properly charge the battery. This is a site that has a good fitment section Fcpeuro.com

As for the starting problem, try once connecting the battery to a second vehicle, and try starting. See if the starter spins easier. That will tell you your battery doesn't provide enough ampers any more, so it may need replaced, but be also sure the alternator puts out the right voltage with the new battery. You may also definitely want to check for current drain when the car is parked overnight, because this can damage a new battery in the long term. If the starter still spins slowly even when connected to a second car, then there it may have a problem - look for the cables around the starter or the starter itself

Jul 10th, 2019, 16:48	#9
oragex Premier Member Last Online: Jul 26th, 2021 21:24 Join Date: Jun 2013 Location: Coldnada	Do you have one of these ? https://www.youtube.com/watch?v=IVDHzTkjHlc It helps because the alternator output voltage varies depending if the battery needs charged or not. Basically, at start up the battery needs charged a little to top it up (i.e. until it reaches some 12.7-12.8V) so the alternator puts out some 14.5v for a few minutes. Then, once the battery has been fully charged, the alternator voltage drops to some 13.5v to power the various electrical car systems. Now, the above is the ideal operation when the battery is in top shape. However if the battery is old, it gets very slow to charge so you may see the alternator putting out 14.5v for long time while driving. On the other side, if the alternator puts out always only 13.5v, even when right after starting the engine, then there is one or more problems: 1. the battery cannot get fully charged, which will damage it in the long term. 2. the battery may be already very worn and no longer accept a full charge so the alternator doesn't even try to charge it any longer. 3. the alternator may not be the correct one for the car and may not put out the correct voltage to properly charge the battery. For example, in these cars there are two different regulators: one for 2001-2004 and another one for 2005-2009. You need to have the correct one for your car year, or the alternator will not properly charge the battery. This is a site that has a good fitment section Fcpeuro.com As for the starting problem, try once connecting the battery to a second vehicle, and try starting. See if the starter spins easier. That will tell you your battery doesn't provide enough ampers any more, so it may need replaced, but be also sure the alternator puts out the right voltage with the new battery. You may also definitely want to check for current drain when the car is parked overnight, because this can damage a new battery in the long term. If the starter still spins slowly even when connected to a second car, then there it may have a problem - look for the cables around the starter or the starter itself __________________ Several Volvo Repair Videos https://www.youtube.com/playlist?lis...ECTts0FSVSOT_c Last edited by oragex; Jul 10th, 2019 at 16:51.