Hi, I’ve just been out to start up my 95 Eunos 1.8 for the first time in about six weeks.
I charged the battery beforhand and it was reading 12.4 volts.
When I started the engine there was quite a loud skreeching from, I’m assuming, one of the drive belts. This lasted about 10 to 15 seconds then stopped. What I did notice was the voltage accross the battery was 12.5 volts while it was skreeching and when it stopped it was 13.7 volts, so I’m assuming it was the alternator belt making the noise. The belts were replaced about 300 miles ago and are correctly adjusted. The alternator pully was rotating when it was making the noise but I couldn’t tell if it was slipping. The alternator spins freely when the belt is off as I checked this when I replaced the belts. I was wondering if the battery was starting to fail and it was trying to pull too much current from the alternator just after start up but as I say it was reading 12.5 volts so not low at all.
Anyone got any ideas as to what could be causing this?
Many thanks as allways.
Dave.
But it will have settled in, and sounds like requires a re-adjustment.
A good battery will be happy to accept a meaty charge for a few seconds immediately after an engine start, and a good alternator will be trying to deliver that current.
Tighten the belt a tiny bit more, this is assuming that the adjuster has not seized and is not preventing travel past a certain point.
As Richard said.
Plus, in this weather, leaving it 6 weeks I’d suspect points to slippy / damp belts etc.
I’d wager giving the battery a trickle charge either disconnected in the boot, or better still removed…would be good policy.
What he said 
Thanks for the replies.
I always disconnect the battery when I know the car isn’t going to be used for a while and the boot lid is left open about six inches so it can breathe. The battery was put on charge before I connected it up to start.
The bit I find a bit odd is that the voltage at the battery terminals reads 12.5 volts while it is making the noise and immediately jumps to 13.7 when it stops.
I’ll check the belt tension again.
Thanks again.
D
Would the charge increase from the alternator once the belt stops slipping?
The internals wouldn’t be turning so fast if the belt was slipping. 
Yes, absolutely. Classic sign of a low battery and slightly loose belt.
The alternator gets really hard to turn if the battery wants to take a lot of current so the belt can slip and squeal. Since the alternator isn’t turning fast enough to generate much current, the battery volts don’t rise until the belt grips.