alternator overcharging

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cyrus
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alternator overcharging

Post by cyrus »

Hi there my '69 saloon has an alternator conversion but recently the battery has started going flat after only 2 days or so of the car not being used. The battery looks fairly new but as it was already on the car I don't know its exact age. When I start the car and measure the voltage across the battery I get between 13v and 19v depending on engine speed which suggests to me that the alternator has a faulty regulator and perhaps has boiled some electrolyte out of the battery and possibly ruined it (it's not the type that you can top up unfortunately)
I am posting some photos of the alternator as I don't know what type it is and where it came from. I am guessing that it is probably from ESM, does what I have look like their ALT100A model to you? :

https://www.morrisminorspares.com/elect ... le-p829750

I am asking because I am not sure if there are lots of quite similar types of alternator around that can be fitted to minors.

This alternator has not been wired in using a RB106 regulator as a junction box, if I wanted the engine bay to look a bit more original can I fit a non-working junction box and wire it up like that? Or does the regulator have to be working, I was under the impression that it was merely a junction box with the alternator conversion, cheers
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Re: alternator overcharging

Post by cyrus »

Whoops photo disappeared :-?
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oliver90owner
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Re: alternator overcharging

Post by oliver90owner »

Looks like a typical Lucas ACR type alternator for which spare parts are available.

If 19 Volts DC has been applied to your 12 volt VRLA battery for any length of time it will be toast!

One cheap supplier sells complete repair kits for £20 delivered? That includes bearings, reg, brushes, com and rectifier. Dunno the quality - chinese, I presume.
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Re: alternator overcharging

Post by Bowie69 »

Dismantle and check, I had similar issue intermittently, only to find a loose wire inside!
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Re: alternator overcharging

Post by cyrus »

Bowie69 wrote: Wed Dec 29, 2021 4:35 pm Dismantle and check, I had similar issue intermittently, only to find a loose wire inside!
Yes could do if there is time, I need to use the car (it's a daily driver) and what with the holidays causing a hold up anyway might just have to order a new alternator asap.
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Re: alternator overcharging

Post by cyrus »

A Happy New Year to all. Well, the new alternator arrived yesterday from ESM and I fitted it along with a good known battery. I'll be blowed if the voltage isn't the same as before! I am getting from 13.5 to 18v on the meter depending on revs. Surely this will damage my replacement battery as well. I am stumped now, anyone else had this on a new alternator? I am expecting to see about 14.5 volts max.
The only thing I can think of is that maybe a DMM is not such a good idea for measuring a fluctuating voltage and that maybe an old fashioned moving coil meter might be more suitable. (Which I don't have). Any ideas?
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Re: alternator overcharging

Post by oliver90owner »

Have you checked the battery in the DMM?

My DMMs do not give readings like that.
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Re: alternator overcharging

Post by cyrus »

oliver90owner wrote: Sat Jan 01, 2022 6:50 pm Have you checked the battery in the DMM?

My DMMs do not give readings like that.
I'll check it but I don't hold out much hope as it seems to measure everything else just fine
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geoberni
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Re: alternator overcharging

Post by geoberni »

Wohhh There... You've most likely got a car wiring fault!

The Alternator is outputting what it senses your car needs.
You've said that your car has NOT used the Voltage Regulator as the junction box, but you've obviously got something as a junction box. However, I'll use the 'more usual' diagram to illustrate the point.
Sensing.jpg
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You are no doubt checking the Battery and Alternator Output Voltages at Point A.

But the Alternator Output is controlled by whatever the Alternator is sensing at Point B.
It's Odds On you have a resistance on the sensing line that is resulting in the Alternator sensing around 14v at Point B, while delivering 18 Volts at Point A.

Check that sensing wiring. What voltage have you got at Point B, compared to Point A, with IGN on but car not running, and then with car running?
You haven't perhaps been fiddling with the wiring recently, perhaps putting an LED in the Speedo to replace the Charging Lamp?
Is your Charging Lamp on when you switch the IGN on, before starting?
Because..
This alternator has not been wired in using a RB106 regulator as a junction box,
You'll have to work out where your sensing line connections are.
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Re: alternator overcharging

Post by cyrus »

geoberni wrote: Sun Jan 02, 2022 11:48 am Wohhh There... You've most likely got a car wiring fault!

The Alternator is outputting what it senses your car needs.
You've said that your car has NOT used the Voltage Regulator as the junction box, but you've obviously got something as a junction box. However, I'll use the 'more usual' diagram to illustrate the point.

Sensing.jpg

You are no doubt checking the Battery and Alternator Output Voltages at Point A.

But the Alternator Output is controlled by whatever the Alternator is sensing at Point B.
It's Odds On you have a resistance on the sensing line that is resulting in the Alternator sensing around 14v at Point B, while delivering 18 Volts at Point A.

Check that sensing wiring. What voltage have you got at Point B, compared to Point A, with IGN on but car not running, and then with car running?
You haven't perhaps been fiddling with the wiring recently, perhaps putting an LED in the Speedo to replace the Charging Lamp?
Is your Charging Lamp on when you switch the IGN on, before starting?
Because..
This alternator has not been wired in using a RB106 regulator as a junction box,
You'll have to work out where your sensing line connections are.
Hi there and thank you. Yes I have been checking the voltage across the battery. Not changed any bulbs for leds except interior light however I will check previous owner has not changed the charging lamp for a led. Not been messing with the wiring myself, at some point the wiring has been re-done because of the alternator, have been driving it like that for 2000 miles or so with no problems. As I said it wasn't done using the RB106 regulator, which is not present, but using connectors. Yes charging lamp comes on before starting then goes out when started.
I will check the voltages tomorrow when it's light and report back, cheers
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Re: alternator overcharging

Post by geoberni »

Well from that feedback, I would say it's very likely that there is a loose or dirty connection somewhere on that sensing line which is causing a volts drop resulting in the Alternator over volt.
it'll be something that's happened fairly recently.
it might even just be the connection onto the Alternator IND terminal, so I'd look there first, then whatever terminal block you have. :wink:

I can't see from your photo if you have a large Connector or individual spade terminals.
Last edited by geoberni on Sun Jan 02, 2022 5:18 pm, edited 1 time in total.
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Re: alternator overcharging

Post by Bowie69 »

The loose wire I mentioned above was the sense wire, inside the alternator, I would take your old one off and check it, it may be a common fault.
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geoberni
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Re: alternator overcharging

Post by geoberni »

Bowie69 wrote: Sun Jan 02, 2022 5:16 pm The loose wire I mentioned above was the sense wire, inside the alternator, I would take your old one off and check it, it may be a common fault.
Yes, however he's changed the Alternator for a new one and the fault has remained exactly the same; thus baring the replacement having been damaged in transit, it's 99.999999% certain that the fault is not within both Alternators.
But it could still be a poor connection at the external Connector, if he just 'Plug n'Played' the replacement without examining the wiring.
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Re: alternator overcharging

Post by Bowie69 »

geoberni wrote: Sun Jan 02, 2022 5:23 pm
99.999999% certain that the fault is not within both Alternators.
I would suggest the probability is a LOT less than that given the number out of the box faulty stuff I get -and having handled a couple of the alternators I am convinced they are the cheapest Chinese knock-offs I have ever seen, so we can reduce it a bit further.

Checking the old one won't hurt, it is 2/3 screws IIRC, and then at least you know.
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Re: alternator overcharging

Post by geoberni »

Well I'm sure he can make up his own mind whether to take the old one apart or simply do a voltage check at the Sensing connection.....
The fault initially appeared after several thousand miles of use, and you're suggesting that the replacement has the same fault straight out of the box.
Now what are the odds of that ..... :-?

But, in light of your comments, I''ll round it down to 99% likely as the fault is not both Alternators.
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Re: alternator overcharging

Post by Bowie69 »

:roll: :roll: :roll: :roll: :roll: :roll: :roll: :roll: :roll: :roll:

Dear me.
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Re: alternator overcharging

Post by cyrus »

Ok had a look this morning and for good measure put a new battery in the multimeter. I also removed the led bulb from the interior light just it case it was wired up weirdly and was affecting something. Checked all bulbs in the speedo and they are all normal bulbs.

With ign off the voltage across the battery was at 12.1v.
With ign on it was at 11.93v

Measuring at the sensor wire :
With ign off 0v
With ign on 11.88v

When I start the engine the DMM goes crazy and jumps around, as far as I can tell the voltage is jumping between 13 and 18v but the meter sometimes flashes negative and the readings are pretty unreliable. I am wondering if the fact that the car has no spark plug supression caps is sending the meter all over the place as it works fine anywhere else or with the engine off. So this test is a bit inconclusive.

I have removed the insulation tape from the connectors to examine, not very neatly done but the connections look ok, as you can see from the pic I have a brown/green wire joined to a brown/yellow, this will be the sensor wire to ignition lamp. But on the other connector I have 3 wires into 2, surely this cannot be correct. The wires going into the top of the connector are brown/blue, plain brown and brown/yellow. The wires at the bottom are brown/blue and brown. The 2 earth wires are not connected to anything.

Without having an RB106 in front of me I can't see whether some of the connectors are common, i.e whether brown/blue and plain brown are normally common. This would mean the A1 and A terminals being common on the RB106. I have ordered an RB106 and will use this as the junction box instead of the connectors fitted.
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geoberni
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Re: alternator overcharging

Post by geoberni »

Ummm...
Trying to keep a logical sequence to all this.

As I read your past posts, this has worked fine for a few months since you brought the car.
You believe the battery has been damaged by over charging.
Your multimeter shows 13-18v at the Battery posts when engine running.
I think something is actually driving your Alternator crazy and it's nothing to do with the Meter and a lack of HT suppression.

Now to your report back above:

So only about 0.05v drop at the Sensing Connection. :-?
What is the connection, is it part of a Large Plug or just an individual Spade?


Now, it would be helpful to read the following in conjunction with this 'Standard Conversion diagram' .....
Conversion Diag.JPG
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I have 3 wires into 2, surely this cannot be correct. The wires going into the top of the connector are brown/blue, plain brown and brown/yellow. The wires at the bottom are brown/blue and brown.
This rings alarm bells.
The 3 x Brown/Blue plus the Brown should be connected together. On the RB106 version A and A1 are connected together, so those 4 cables are shorted together. NOTE, no thicker Brown/Yellow, this should be redundant!
I have a brown/green wire joined to a brown/yellow, this will be the sensor wire to ignition lamp.
Or is it? The Brown/Green should be redundant..., the thin Brown/Yellow, which comes from the IGN Lamp should now go to the Alternator sensor connection. On the diagram above they have a new Yellow cable.
Is that where the Brown/Green goes, instead of a 'new yellow'?


I think we are trying to work out a bodge wiring job here, and doing it without being there to see all the different connections 'Brain Ache' material....

QUESTIONS
- Where does that Thicker Brown/Yellow go?
- Is the Brown/Green being used for the Sensor connection?

- What actual OUTPUT connections have you got between Alternator and the Solenoid?
The 2 earth wires are not connected to anything.
Hopefully they are connected to each other.
I believe this is the earth path for the Wipers.


I think this has always been wired incorrectly.....
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Re: alternator overcharging

Post by cyrus »

Thanks for your time geoberni, do appreciate it yes I agree , a brain ache and it should be straightforward. Will have to look again in the light tomorrow morning to answer some of your questions. The wiring on the car seems unmolested except for the wires associated with the alternator and control box, under dash and behind speedo is totally unmolested and original . Ok here goes:

1.) You mention 3 brown/blue but I only have 2?

2.) Yes the brown/green is being used for the sensor connection and is joined to the thin brown/yellow so this looks correct I think

3.) Yes the black earth wires are joined together and terminate in a spade connector but this just dangles and is not connected to anything.

4.) The thicker brown/yellow wire is the main wire to the alternator I am pretty sure of this but will beep it out with the DMM tomorrow to make absolutely sure

It looks like the 2 original wires from the dynamo have been used to connect the alternator up as the colours are correct and there are no new wires
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geoberni
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Re: alternator overcharging

Post by geoberni »

1.) You mention 3 brown/blue but I only have 2?
Well hopefully you're mistaken, because there should be 3 Br/Bl and only one Br.
If you're right, someone has rewired it with non standard colours, at least in part, so you're really in trouble... :roll:
2.) Yes the brown/green is being used for the sensor connection and is joined to the thin brown/yellow so this looks correct I think
OK, that makes sense.
3.) Yes the black earth wires are joined together and terminate in a spade connector but this just dangles and is not connected to anything.
It depends on the years of the car, but one of those goes to the body, the other comes from the Wipers or perhaps the interior light.
4.) The thicker brown/yellow wire is the main wire to the alternator I am pretty sure of this but will beep it out with the DMM tomorrow to make absolutely sure
Aghhh. This might be the problem. There should be no connection from there to the alternator. That used to be from the Dynamo to the Control Unit.
The only output from the Alternator should go direct to the Start Solenoid, or Pull Start switch and thus the Battery.

One thing I'm curious about, if the Alternator output has been fluctuating so much, have you noticed any slight pulsing of lamps, such as interior light if you have one, or the sidelights?
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