7 replies to this topic

[yorkshirechris]

Right, this might be a simple one or I may need to call on the ears of one of the more experienced people.

When I got my new mini (evelyn) took it for a service on Saturday and realised the alternator was unplugged. The multiplug was definately unplugged, and had been unplugged for a reason. Quite bizarre. So we thought, maybe it's because it's knacked. The alternator that is.

Anyway, after having a couple of starting problems (this was the day before) I got my trusty RAC battery charger out and stuck it on the battery. It was charged at like 5% - due to the alternator being unplugged (I assume). After leaving it on "fast" charge for 3 hours it was still only on about 10-15%.

Battery dead then. So we replaced the battery with a decent 600amp one.

Now here's the dilemma.

Tested the battery, 12v. Started her up, getting 14.2v at the battery. So safe to assume all is well with the Alternator, right?

So WHY was the alternator unplugged?! Would there be any good reason for this?

A friend has suggested the regulator (?) may be faulty or not working, so instead of saying "right the battery is charged, stop charging it now" it doesn't, and consequently the battery gets fried.

Naturally I don't want my new £60 battery fried, so can anyone shed any light on:

1. Why was the alternator unplugged in the first place if it's working okay
2. In fact have we tested it properly?
3. How to test the Regulator part of the alternator, in leymans terms please.

Thankyou kindly

[HARBER07]

In answer to number 2:
This is always the way i test the battery and this is how they check it at my garage so should be correct.
dont know about the rest though.

[Grimmy@JHE]

14.2 is fine chris... maybe someone knocked the clip and it fell out threw vibration

[yorkshirechris]

Yeah but what about the regulator?

The bit that stops the alternator charging the battery when the battery is fully charged?

I don't want the brand new battery being fried!

The plug was totally out and dangling next to it, definately hadn't been knocked out or fell out due to vibration, well I say definately, I'm 90% sure.

Edited by yorkshirechris, 28 January 2008 - 09:59 PM.

[Grimmy@JHE]

who took it out? ask them?

[yorkshirechris]

I'd rather check it over myself properly if I can.

[icklemini]

The Regulator only controls the output voltage - yes it can be tested but you'd need some gear for it to do it on the bench..

if its showing 14v and an increase in revs results in the same voltage - then assume all is well...

hth,
Dave

[MiniMick]

The Regulator only controls the output voltage - yes it can be tested but you'd need some gear for it to do it on the bench..

if its showing 14v and an increase in revs results in the same voltage - then assume all is well...

hth,
Dave

As above
If the previous owner has had problems they may have forgot to replace the plug or not fitted it correctly after testing
If i've suspected an alternator overcharging intermitently in my car i've kept an eye on it by checking it with a metre 3 or 4 times a day for a week and if it's been ok for that long don't worry
I have had one that was faulty on a mk 2 escort and all it did was make the battery go fat, it could have gone pop thats why i always do a weekly check on my motors (not whilst there being rebuilt though)