Paulyy

i'm having a funny charge issue.

when i start the car in the morning, it usually starts. it'll idle and the volt gauge will say just over 12v. Sometimes when i rev it the belt squeals, but just that 2 mins after it has started. usually when i rev it. Then the volts will increase to ~13..

After a drive, say 30-40 mins the volt meter will go down to 12v and sit there. last night i had turned the radio off, and any accessories, except my driving lights. the volts slowly dropped.
Parked up, went out for a little while (hour-ish) started the car, and it struggled to start.

if the car has sat for a little while, it may struggle to start.

I also don't have no assessors on while the car is off.

Ground have been cleaned on chassis, engine and around battery.
Battery is in the boot/trunk

I have the alternator out. connecters look average. will clean.
will test regulator. its been replaced at some time.

What else to check?

Adonay

Stock alternator? Sounds like the voltage regulator but could be alternator needing a rebuild . is it easy to turn ? How old?

Paulyy

stock alt.

It's been rebuilt apparently spins nice and easy.

gruhsy

I say voltage regulator also.

bumflick

I ha exactly the same issues on my 86. Nissan quest alternator fixed it.
Before you do that, however..
If you are getting some belt squeal, have you done the simple thing and checked the belt tension? When I went back together with the Nissan alternator, it did not appear to have fixed the issue, but my problem was a poorly adjusted belt.

Paulyy

I could change alternators, but i rather just solve this problem.

The voltage regulator is some other brand. says made in Germany.. but not bosch.

Why is the porsche branded one so much more expensive than a generic bosch one? apparently they're all the same.

JET951

did you check that its charging? muiltimeter across battery terminals?

Paulyy

I didn't. cant now either. Slipped my mind to do that.

Paulyy

So alternator got tested fine.

Replaced the voltage regulator with a bosch unit. even though the other one got tested fine. the bosch had more meat on the contacts.

I'm going to file the cable contacts for a clean surface new washers and hope it works.

User 52121

Alternator is grounded through the mounting bracket.

Try cleaning the bejesus out of all the contact points between the alternator, bracket, and block - or ground the alternator direct to the chassis.

Something I never did before switching to the Nissan alt... and initially had issues with the Nissan alt and low output. After grounding the alt case - problems went away. I then recalled how crusty and corroded the old bracket, and bracket bolts, were. Made me wonder if that was part of the issue with the low output I saw with the stock alt.

Paulyy

Good idea. I'll do that too. Thanks Jim.

mahoney944

Yeah I agree. When I did my Nissan alt mod. Which is highly recommended. I sand blasted the mounting bracket. This fixed all my issues. I still want to get new battery cables but that's more of a just to be sure thing, no issues..

I also found my stock alt had chunks of leaves that got sucked in from the stock vent to the alt. Probably what was causing my initial issues, over heating

Paulyy

I have no vent on mine. gets in the way of the turbo.

Also my battery is in the rear so replacing a cable is more difficult. looks to be in good condition.

Rob in Oz

Had the same problem in my 968. Auto electrician diagnosed faulty cabling between alternator and starter motor. Replaced, problem fixed: $168.

Droops83

The above plus the grounding issue that Jim mentioned are both great suggestions. It has been a while, but I have seen several 944s with very corroded alternator-battery-starter cables. Check for voltage drops at each point with a good multimeter.