Hi guys,

After thinking I had battery/alternator problems these are the readings ive taken after battery was on charge for 73 hours.

Battery alone..13.40v
Car turned on..11.97v
Car turned on with everything on (lights/heaters/wipers/screen heat)..12.03v
Car after it has been over 3000rpm (to engage alternator)..13.98v
Car held at 3000rpm..13.62v
Car held at 3000rpm with everything on..12.88v
Battery alone at the end (car turned off)..13.22v

Does this all look ok?? Battery light was on initially until revs were taken over 3000rpm then it went off.

I think everything maybe ok? Is this the case?

Thankyou.

 

Alternators Fubar'ed .. Regluator's not erm .. Regulating

 

alternator should charge between 13.6v 14.2v from initial startup without having to rev it for it to engage as said above alternator fault

 

For sure?

If you look it does get up above 13.6v

 

but it isnt doing it all the time!

alternator is shafted fela as said above, no point should it be below 13.6, ideally 14 min.

Car turned on with everything on (lights/heaters/wipers/screen heat)..12.03v..........no good
Car turned on..11.97v.....no good
Car held at 3000rpm with everything on..12.88v ............no good

 

Ok thankyou.

Can anyone recommend me somewhere to get one, for a 3 door cosworth, and a new regulator aswell. Might aswell do um both while im on.

 

One on eBay mate.

 

Could you point me in the right direction please Mat?

Does it include the regulator too?

 

Give me 5 mins mate I see if I can see it again.

 

Item number....370537191644

 

Regulator is part of the alternator mate.On some they are screwed to the rear of the alt,easy swap but if you replace the alt it will be fitted with a new reg anyway.

 

Fantastic stuff.

And thanks Mat. Hope this is the issue and it aint something else. Dont think it can be actually.

 

Thats cheap,I just fitted one on a pug 106 derv,£95 !! from local m factors.Cheapest I could find on the bay was £79 with tenner post.

 

No probs... Glad I can assist.

 

unless the main power cable to the back of the alternator is loose or seriously damaged through heat from the exhaust manifold i wold say im %100 sure

 

One more thing though,if your not using your car get a reading off the battery now,let it stand for a few days and check again to see if its dropped.I only say this because when I first got my black sapphire the battery had been left flat for that long just trying to operate the windows would cut the car out.Then after charging it would only hold charge for a couple of days.

 

Also load test battery if you can. If a cell is down it wont hold a charge. Your probs a definately alternater but worth checking or changing battery at same time. You know your good for winter then. Only time you tend to drive it with most things on. Heaters screen heaters lights etc.

 

Going to get my mechanic to come check voltage at alternator. If i need a new one i will get one sorted. Also going to get a new battery aswell, as i dont know the condition of the one on the car.

Thanks everyone.

 

it does sound as if the rectifier isn't working well.
you can replace rectifier cheaply enough from an ebay part.
however you may just have too much load on the alternator, mine for instance on my xr2 couldn't maintain charge on a 14.4v regulator, it was only producing 13.6-13.8v at best.
so i got a 15v regulator and voltage went up to a constant 14.4v, sometimes hits 14.5v, which is acceptable and charges much better, but i think i have too many electrics for a 90 amp alternator, still need to blip throttle on start up to get it running though, properly lazy, maybe the pulley is a bit big.
i'm thinking a 180amp vw one or fitting a clutch mechanism for the pulley for extra free power and less strain on crank nose during gear changing.

 

didnt know it was for a cossie, just assumed it was the zetec s!

checking wiring along chassis leg is very important, little blue wire and big red cable perish like mad, had to change/repair loads of them

also engine/bellhousing bolt earth wires fail on em too

Sean.

 

Thankyou.

Mechanic is coming on friday night, i will get him to check it all out.

 

Thats definetly an charging problem (On the rectification side) or a regulator.

With a recon alternator you should get a new regulator as well.

The charge output is fine so long as it can overcome the internal resistance of the battery, the greater the difference the greater the charge. But not to much hence why regulation is required.

As a rule you never want to be seeing anything less than 13V WITH the engine running under load, ideally slightly more with no load.

One last thing that may be worth doing is checking the power from the alternator itself, where the heavy duty read cable connects, just be careful of the pulley/belts with the engine running!

Martin

 

Doesn't sound that bad to me mate, its a 3dr isn't it? if so, they always need revs to kick the circuit into charge. Is it still above 13v with normal headlights lights on at 3000rpm?

The heated screens etc almost always overload the standard alternator and wiring.

 

Stu, I will check with headlights and wipers on tomorrow. I will check once it's been over 3000rpm once and then I will check holding it at 3000rpm.

 

Agreed the readings arn't to bad, but something isn't right by the fact your dash light is staying on!

By looking at your readings below, are you having to rev to get it to start charging? If so then something is wrong with the field energising!

Another thing that can cause problems, is if someone has replaced the warning light bulb with the incorrect type, unlikely as they don't typically go wrong, but it has been known!

Martin

 

Martin.

The light stays until you rev it above 3000rpm and it extinguishes straight away.

My mechanic is coming around tomorrow night. What volts should I defo be expecting direct off alternator terminals?

 

if you can do without the car doc couple of days, whip the alternator off and get it to an auto electrician, much cheaper than buying new!

 

Oh right I never knew it extinguished, you still have a problem, you shoulden't have to rev it to start charging, agreed they are known for being a LITTLE lazy!

It's either lazy diodes or something is wrong with the field circuit (Check the thin blue wire WITH the ignition on, what power is present?)

Ideally the power at the battery should match that at the alternator, a common problem is the heavy duty cable running from it to the battery builds resistance over time and so you get a loss between the two (Akin to the fuel pump circuit) which, incidentally is another chronic weak point if you diden't know?

Martin

 

Fuel pump has been re wired, with a 44 and runs alone. As will the fan loom come June, once its on the road its going down to Paul at RS spares for a new one.

Im going to check there is no loss over cable like. Will visually inspect them all too.

 

Oh and thanks for your continued help Martin. And Stu for that matter.