13 replies to this topic

[Zauster]

Well, I posted a while back with my issue and after replacing everything I could think of I am no further ahead. My 95 Mini started with a dead battery but after a boost would remain running. Every now and then, even with a charged battery, the starter doesn't turn over the engine very quick.

Now, after replacing the battery, 70amp alternator (& voltage regulator), and diode, my battery still drains. When you start the car, the Voltage at the battery slowing increases to 13.10V but once you turn the headlights on, it starts to drop. I reseated the ground strap in the boot and cleaned the connection at the starter but no luck. If I try and check the Volts at the alternator or the starter when the car is running, it just reads random with just one end connected so I don't know what's going on. (With the car off, voltage at the starter is equal to the reading at the battery).

The Mini has not been messed with and everything is original. Please help as no one here knows how to work on these (also no mechanic I really trust) and it's really expensive to bring in parts (not only on freight but 27% import duty).

Thanks - David
Cayman Islands

Edited by Zauster, 25 August 2008 - 02:47 AM.

[dklawson]

Now, after replacing the battery, 70amp alternator (& voltage regulator), and diode, my battery still drains.

If I try and check the Volts at the alternator or the starter when the car is running, it just reads random with just one end connected

The diode pack is internal to the typical Lucas alternator except for the very, very early ones. Why did you buy both an alternator and a diode pack?

Are you saying that you disconnected the alternator with the engine running? If so... that is likely to be part of your problem. You should NEVER unplug the alternator once the engine has started. This can permanently damage the alternator.

First, does your charge/ignition warning light operate? You should see the following scenario:
1) Ignition key "off", ignition warning light = off
2) Ignition key in the "run" position (with engine off), ignition warning light = on
3) Ignition key in the "run" position with the engine running, ignition warning light = off

Please post back with answers to what you've done and why... and what the ignition warning light is doing.

[bananaman]

Check your engine earth braid, from above the clutch housing back to the egine steady mount on the bulkhead. If this is damaged or loose this can give you the same symptoms.

I tend to put another across the other sdie with an additional engine steady.

Tony

[Zauster]

Sorry, I'll give a little better explanation. When the car is running, and everything hooked up, I turn on my amp meter and as soon as I touch the positive end to the alternator wires, or the starter, it goes haywire and I can't get a reading (this may be my meter though it works on the battery with or without the car running).

My diode is a square external black box, one end bolted under the alternator belt protector/cover on the back and the other end plugs into alternator. This did not come with the new A127 70amp (1980-96) alt I ordered from Mini Spares, so I sourced another one which is cylinder in shape but made no diference so I'm back to the original diode.

The charge warning light does work as you mentioned and goes out once the car starts.

I did check the earth braid and it is intact. I oiled it to ensure it remains in good shape but as Tony mentioned, I too may add another ground strap just to make sure.

[dklawson]

Your car looks much newer than any I would expect to have any external alternator components. I cannot comment on the external components you're using.

You have an ammeter... and you "turn it on"? Something is not right here. I'm not familiar with Minis ever coming from the factory with an ammeter. If they did, someone please correct me.

Ammeter's fall into two categories, direct and shunt. Most are direct. The way they work is to go in series with the power flowing to/from the battery via the alternator. You do NOT switch them on and off as they appear as a conductive path that must be present for the system to charge. Perhaps you meant a volt meter?

Faced with your situation, the availability of parts, and the cost of importing them... have you considered an alternator swap from a vehicle other than a Mini?

[taffy1967]

No Mini came from the factory with an ammeter fitted as standard.

[Zauster]

Thanks for all the quick replies. What I am trying to expain is how I'm testing the outputs and readings from the alternator and battery with a hand held electrician's amp meter (AC/DC & volts). When the car is off, battery charged, battery reading is 12.92Amps (does not decline overnight). Once started the battery slowly climbs to 13.10Amps. However, if you turn on the lights, the battery slowly starts dropping in Amps, meaning the alternator cannot keep up with the output. I thought at first, before testing, I would replace an unknown aged battery to start with a clean slate. Once the new battery was charged and installed, this process continued so I ordered the upgraded 70Amp alternator. This still did not fix my problem and as it is my wife's daily driver, I'm getting things replaced as she doesn't like the word "fixed".

So, new battery and alternator and still no resolution. I now have my wife sit in the car for an extra minute with the car idling before she can turn it off in order to give the battery a chance to charge.

David
Mini in distress

Edited by Zauster, 25 August 2008 - 08:10 PM.

[dklawson]

Please accept this as a minor correction, not a criticism.

You are not talking about amperes (amps), the values you are talking about are volts.
"When the car is off, battery charged, battery reading is 12.92Amps (does not decline overnight). "
Amps or amperes is the flow of current and is only present when there is a load such as a light bulb or motor that is using electricity. If with the engine turned off you were measuring a current flow of 12.9 amps (enough to run the headlights and perhaps the ventilation fan) your battery would be dead by morning.

Voltage is the "push" or force to move the electricity. Your values of 12.9 volts and 13.1 volts do indicate a problem. Basically it is saying that your alternator is not working. Start as Tony suggested by checking all your earth connections. Remove the earth cables where they contact the car and engine and give the cables and the surface they mate with a good cleaning. This includes where the cables attach in the boot as well.

Again, I don't understand your reference to an external alternator diode so I can't really comment about what's going on. A quick Google of "A127 alternator" resulted in this site:
http://forums.lr4x4....mp;#entry139878

The back of the alternator should look like this:
http://www.minimania...ig/gxe2297a.jpg

I'm not sure why you have an external diode pack on your car's wiring. What year is your car? based on the picture above, you should be able to just plug the old alternator 3-pin plug directly into the A127 without any external components. You may find that your external diode is what's causing the problem.

Please download this PDF and give it a read. It will load slowly so be patient.
http://www.qxcomponents.co.uk/tech.pdf
It mentions that the A127 is internally regulated. Therefore you shouldn't need any external components. You will have two large output spade terminals and a small spade terminal for the warning light connection. That's all.

[Zauster]

Appreciate this Doug - I knew I wasn't explaining it correctly.


Great work finding the pics. The first pic shows the same external "diode" (black box) that I have but the plugs are the same as the second pic and not the first. I'll try removing the "diode" first and see what happens - hopefully no damage will have been done. Then I'll make sure to remove, clean and tighten all earth connections and maybe add a new one from the block to body.

I'll let you know how it goes tonight.

Thanks again!!! David

[dklawson]

When you post next time, please tell us the age of your car as well. I work very little on "newer" Minis but once I know what year your car is, I can at least look at the wiring diagram for that year.

[Zauster]

OK. It's a 95 Cooper with A/C [we currently don't use it] and all stock. As My wife wants a stereo in it and will probably run the A/C, I wanted to upgrade the alternator so paying for it and not really needing it wasn't a huge deal.

As Doug mentioned above, I disconnected the external diode and it is definitally charging more now. However, once the headlights go on, it slows the input to the battery to 12.7 Volts and not sure if it stops there but it is a lot lower than what I was hoping for [battery was at 12.49 Volts when engine started without diode so the battery was not fully charged]. When the car is running, it charges the battery quicker and goes up to 13.34 Volts when first started and levels around 13.2V. Am I back to normal or should I try and measure Amps? I'll try and get a new ground strap on tomorrow and see it anything changes.

Cheers - David

[dklawson]

Your car is truly too new for me to offer more help. It will be significantly different from the Minis I'm familiar with so I must defer to others on this board more familiar with late model Minis.

I wish I could be of more help.

[Zauster]

Thanks everyone! Once I added the extra ground strap and removed the external diode the mini seems to be operating normally. I'll do some more tests on the weekend to make sure as right now we're buckling down for a huricane that should arrive Thursday/Friday.

Cheers - David

[ferrox_666]

Its a ground loop isolator (inteference supressor)
to stop the cakle you sometimes hear through the radio..