42 replies to this topic

[TA2DMAC]

Yup, green light is rear defrost.

[TA2DMAC]

Had the alternator rebuilt about a month agteryo.
Drove to the store the other day and on the way back I stopped to look at an old Austin Healy.
When I went to start the car again it was completely dead. After getting a boost I got the car home took the battery out and checked it with multimeter and was getting 16.4v reading. I'm thinking the battery is toasted and it overcharged. Any Ideas?

[tiger99]

First, check your multimeter against something known to be accurate, just in case.

At 16.4V, I would say that the battery is well fried, but would expect other nasties too, like failing light bulbs, which is why I initially suspect the multimeter.

[dklawson]

Wow! That really is high. How confident are you that your meter is accurate?

I have seen racing alternators that put out 16V but I don't know what the long term affect of that voltage would be on a street car battery.

[minimarco]

hmm, strange that the front valance is still like the mk1 cars. Is that original? If so, I wonder why they kept the style for the Canadian market. I like it rounded like that better than with the brake cooling cutouts.

Is Kermee like that too? I can't really tell by the picture in your signature.

Edited by minimarco, 25 July 2012 - 05:20 PM.

[1964Woody]

A variety of changes had to be made for Canadian/US Minis to meet the safety standards of the day. That was one of the reason that they eventually stopped selling them here- could no longer meet the increasing safety/efficiency/pollution standards.

Tiger99- you are right that they didn't sell huge numbers of Minis in North America. It was nothing like the Japanese market. But you are wrong that most people wouldn't recognize a Mini. It never ceases to amaze me when people want to talk about my car and they tell very nostalgic stories. It seems everyone you talk to had their first _____ in a Mini. Whether it was their first car, their first date, their first major epic road trip or their first ___ in the back seat. It really is surprising. Those without nostalgic stories say "hey, its a Mr. Bean car". It really is surprising. The downside is that you have to drive properly and can't pick your nose because everyone is looking.

[minimarco]

And you have to wear pants.

[nala56]

Sounds like you need new alternator to me, as far as i'm aware there are no brushes in an alternator just a rectifier. if ign warning light is going brighter when you rev the engine its the alternator, pretty sure on that one, but take your car to your local car spares and they will test your batt- and alternator for free.. Alan

[tiger99]

The alternator also contains a voltage regulator, which is replaceable, if the part is obtainable. If the regulator fails, you get no charge, or incorrect voltage, which could be high or low. If there is really 16.4V, the regulator has failed, or for some unrealistically improbable reason there is far too much residual magnetism in the alternator rotor. (The regulator controls the flow of current through the field winding, which is on the rotor, but can only cut the current off in the extreme case that the voltage is going too high, it can't reverse it to cancel residual magnetism.)

[dklawson]

as far as i'm aware there are no brushes in an alternator just a rectifier.

Actually, alternators do have brushes just like dynamos. When the brushes reach their wear limit you will typically start to see a flickering ignition warning light as the brushes bounce against the slip rings. That won't cause over charging but it can potentially damage the slip rings.

[tiger99]

Doug is correct, and the brushes are the only way that the field current, congtrolled by the regulator, can reach the winding.

There is a class of alternator, called permanent magnet alternators, which do not need brushes as the rotating field is produced by a permanent magnet, however they require some kind of chopper control at the output, where the voltage may reach over 150V at full revs, needing higher voltage rated rectifiers, switching transistors that can handle the full output current, and complex control electronics, or phase control with SCRs or similar, very noisy electrically, so they are hardly ever used on cars. The controlled field current in a normal brushed alternator is tiny by comparison, and the regulator circuit is cheap and simple.

[Spitz]

Just noticed the valance now that you pointed it out.
It's either been replaced with an early MkI type....or it's an optical illusion
Non of mine built for CA have the early type front valance ( except an early Mk1 S shell I have )

[TA2DMAC]

Took the battery to have checked. Totally fried. It had a charge but wouldn't hold it.
I think I scared the lady using the tester when I was actually happy it was a bad battery.
I'm taking the car to the shop to have the alternator rechecked to make sure there are no more issues.