Alternator question

From CEM to VEM, from LED to lightbulb and more. If you have an electrical problem, like a broken info-centre, search for answers in this category. This is also the place to be when you expect the problem to be of an electrical nature...

Moderators: jifflemon, coyote1980, Rachel

Post Reply
gltease
480 Veteran
Posts: 704
Joined: Fri Jun 23, 2006 12:09 am
Location: UK
Contact:

Alternator question

Post by gltease » Sat May 27, 2023 12:37 pm

Hi all,

New alternator and battery fitted.
On initial start up and idle no apparent charging.
Go for a drive about 2 mins in, normal charging (13.5v) resumes.
Idling also results in normal (13.5v) charging, stop then start, poor charging until a drive.
This behaviour is consistent ..

Any ideas? Thanks

C
'88 Volvo 480 ES
'97 Volvo 940 Turbo

User avatar
Jay-Kay-Em
480 Rookie
Posts: 428
Joined: Tue Nov 27, 2012 10:42 pm
Location: Huntingdon
Contact:

Re: Alternator question

Post by Jay-Kay-Em » Sat May 27, 2023 1:23 pm

Sometimes alternators need a slightly higher RPM than idle to "kick-in". Once they're going however, they're going.

If you start the engine and slowly bring the revs up, will it kick in just the same (eliminating the driving part)?

This all might suggest the pulley is the wrong diameter on what you have fitted and its geared too slow - put a vernier on new v. old pulleys - that's assuming the old one didn't give this problem.
Jay-Kay-Em
-------------------------------------
Click here for My 480 Turbo Diary
Click here for My Cars

jifflemon
480 Is my middle name
Posts: 2464
Joined: Sat Dec 17, 2016 11:03 am

Re: Alternator question

Post by jifflemon » Sat May 27, 2023 5:12 pm

When you switch the ignition on, does the battery warning light come on? This is what starts the charging process. Sometimes a good rev can cause self excitement and trigger charging, but not always.

Also 13.5v is right on the edge of actually charging; have a look at the how to section on my volt drop topic

jifflemon
480 Is my middle name
Posts: 2464
Joined: Sat Dec 17, 2016 11:03 am

Re: Alternator question

Post by jifflemon » Sat May 27, 2023 5:19 pm

Oh and the thing could be a loose belt; poly rib belts grip quite tight so don’t squeal as easily as single v belt when loose

gltease
480 Veteran
Posts: 704
Joined: Fri Jun 23, 2006 12:09 am
Location: UK
Contact:

Re: Alternator question

Post by gltease » Sat May 27, 2023 5:21 pm

jifflemon wrote:
Sat May 27, 2023 5:12 pm
When you switch the ignition on, does the battery warning light come on? This is what starts the charging process. Sometimes a good rev can cause self excitement and trigger charging, but not always.

Also 13.5v is right on the edge of actually charging; have a look at the how to section on my volt drop topic
Thanks for all that, I'll get back to the car tomorrow AM and have a run through the how to and report back after that.
cheers
'88 Volvo 480 ES
'97 Volvo 940 Turbo

gltease
480 Veteran
Posts: 704
Joined: Fri Jun 23, 2006 12:09 am
Location: UK
Contact:

Re: Alternator question

Post by gltease » Sun May 28, 2023 12:59 pm

All good now, nice healthy 13.8v.

The little spade connector that plugs into the regulator was frazzled, its been stripped soldered and refitted.

During my checks the earth from battery to body was corroded and pretty much fell out of the connector so that's replaced too.

Thanks all for the excellent tips .

Colm
'88 Volvo 480 ES
'97 Volvo 940 Turbo

Alan 480
480 Is my middle name
Posts: 1489
Joined: Sun Aug 28, 2011 9:03 am
Location: Aberdeen

Re: Alternator question

Post by Alan 480 » Sun May 28, 2023 6:51 pm

jifflemon wrote:
Sat May 27, 2023 5:12 pm
When you switch the ignition on, does the battery warning light come on? This is what starts the charging process.
aye same happens if the bulb fails, so ALWAYS check it comes on, better half found out the hard way ;)
Alan

480 ES 2litre 'Celebration' ? , C30 1.8ES, SS1

Post Reply