Min alternator volts

[Daveo]

Does anyone know exactly the minimum Volts an alternator can be producing with still enough to charge the battery? For a 1991 1.0 saloon.
Cheers liam

[Asa-James]

ideally running you want something between 12 and 14 volts, but an alternator wont just charge a completely flat battery. anything over 14 volts and your asking for trouble

[Daveo]

Well I've put a volt metre across the battery yesterday because my battery died so when i got the car running and I got just over 13v. I've recently been experiencing a slipping fan belt but however tight I try to keep the belt It will always return to slipping again within a matter of time. Can a slipping fan belt cause the battery to die?

[Asa-James]

It can cause poor recharging, have you checked for a battery drain?

[mowgli]

what is causing it to slip if its massively tight??? when did you last put a new belt on??

this time of year, a battery simply doesn't get enough charge on short journeys (less than 30 miles)

you are no doubt running with lights, heater, wipers, demister & radio on all the time... it takes its toll...

if its doable, when you park up , turn all the non essentials off & let the car run for 5-10 mins to let it charge up a bit.

the battery could also be goosed, get it tested by someone with a discharge tester who doesn't get commision on battery sales

[Daveo]

I'm not sure what is causing the belt to slip, could the alternator adjusting bolt be slipping on the bar and causing it to loosen?

I do journeys that are about 5-10 miles most days of the week, and probably doing more than a 30mile trip every so often being around once every 2weeks.

The actual belt itself is no more than 500miles old and the battery is about 2months old.

So I'm abit stumped, my real question is that is just over 13v enough to charge the battery properly?

[Asa-James]

Yes, if I remember rightly (and I rarely do) 13.4 volts is about what they should run to. I may have made that figure up, but it seems to ring a bell. When you next adjust the alternator, put a couple of witness marks on the bracket and see if it slips over a couple of days.

[Jon_nova1]

14.4v?

[pie]

^^^

on idle 14.4 volts is normal

13 ish volts with everything on (just goin off my cav)

[marc69]

Is the altenator earthed properly? The 1.o has an earth strap from the altator braket to the engine, without this it will not charge the battery properly.

The altenator lower bracket, are both bolts secure and tight? This could be causing altenator movement.

If the belt is only 500 miles old, it will have strectched very slightly since new and will need adjusting, make sure the bolts are reallly tight after adjusting but, don't make the belt too tight otherwise you'll knacker bearings and snap the belt. A slack belt will limit charge when other electricals are on.

[mowgli]

if you have done all of the above & its still giving you gip, get an auto electrician to test the alternator

[Daveo]

The ground is all there. I believe it could be a case of it being a new belt that its stretched out. I'm going to tighten it as much as I can and see where I can go from there....

[meritlover]

is it the right belt? if its not the right width of 'V' it wont make contact properly and slip

[Daveo]

It seems to sit in the pulleys correctly, I bought it from euro's and it's meant to be the right one

[jimbob-mcgrew]

is it at maximum adjustment ? youve got the wrong belt if so, too long

i usually jam a breaker bar inbetween the block and alternator (like a third hand) to keep tension on the belt while you lock the 2 x 13mm bolts up

a good tightness is = you wanna be able to smoothly rotate the belt thru 90 degrees once the nuts are locked. check theres washers on those nuts too, could slip without any. and make sure you reconnect the earth strap from the inlet manifold to it (if the 1.0 litres have those, i forget)

where abouts are you in croydon by the way mate, no that far

[jimbob-mcgrew]

might sound stupid, youve probably already done it.

check your battery water level too, it cant charge properly if its too low. de-ionized waters cheap.

[Daveo]

It's not at maximum adjustment, sits about half way along the bar.

I'm not actually too sure about the washers, I can't remember if I put them back on when I change the alt, ill have a look in abit.

I'm just by waddon mate

[jimbob-mcgrew]

oh you changed the alt. did you. 13+ volts sounds fine.
what was the old kicking out ?

check for battery drain like asa-james said, there might be something in the system stealing power whilst the car sleeps at night. ive seen that alot with sub amps and additional added electrics that havent been wired up properly

about an hour from you in londons crap traffic

[Daveo]

What's the best way to check for a drain? I have got an alarm on there so could be that.

Where abouts are you?

[Daveo]

Just been having a fiddle in the freezing weather and jammed a pole against the alt and got it a hell of a lot tighter and jump started her aswell so now the squealing has gone and I'm reading 14.4v at idle with everything off so appears to be running ok

[marc69]

If it was squaeling that is definately the altenator belt, take the car out for 30 minutes drive and hopefully you'll start in the morning.

[pie]

14.4 sound better fella

[jimbob-mcgrew]

might be ok now then ?
give it a day or 2 to see.

if you experience further problems, you can check for drain with a multi-metre, but theres a certain way of doing it, it involves disconnecting one of your battery terminals and bridging the gap for a reading. i forget exactly how, let me get back to you on that one ! as if you dont do it right, it might kill your multi-metre.

i remember the reading should be very low tho, around 0.03 amps is normal if my memory serves me.
a friend of mine had his stuck on 3 amps, and it was killing his battery pretty much overnight.

[Daveo]

Did abit of driving today and is going as good as even. I will give it a couple of days to know for sure.

Could it of been a case of the new belt stretching? Rather than the alt becoming loose?