Hi,

Your responses last time I posted were very helpful so here goes again. Apologies upfront because I have used generic terms and wording because I am just a guy in his shed poking about with a multimeter and power supply and this alternator stuff is new to me. I'm careful not to use technical terms I have read/heard because I probably don't have the proper knowledge that goes with it.

I am in the process of swapping an alternator in an old vehicle. It has an external regulator and I am changing to an internal regulator version. I currently have only the wiring loom and vehicle electrics on the bench - I do not have a running vehicle and am bench testing by spinning the alternator with an electric drill. I have the complete electric components of the car on the bench functioning as it would if fitted in the vehicle. Everything works as intended.

I have the original externally regulated alternator working and spinning it with the drill results in the charge lamp turning off and the battery being charged so I am satisfied that it is working how it is intended. And now I want to swap to an internally regulated alternator.

I have bench tested the internally regulated alternator (second hand) connected direcly to the battery with a lamp connected in the lamp circuit. It works as it should, the lamp turns off and the battery is receiving charge.

The original circuit diagram is as follows: (apologies for the rough diagram - the factory manual doesn't include details of the inside of components so I made my own by checking online for similar and poking about with a multimeter to confirm and then piecing it all together to work out what does what)



If I understand the above drawing correctly, during the start cycle the fuel pump and choke are powered from the start circuit. When the alternator starts spinning and producing 'power' the contacts in the voltage relay side of the regulator switch which connects the lamp wire and voltage regulator coils to the b+ terminal through the voltage relay contacts (I'm not considering what happen in the voltage regulation side other than the fields initial power). The B+ voltage is 'fed' back into the lamp wire resulting in the charge lamp 'turning off' and the coils in the fuel pump relay energising and switching contacts so power is then supplied to the fuel pump (through a resistor) and choke by the ignition circuit. The engine is now running.

Looking online I have followed common process and connected the internally regulated alternator as follows:



When I remove the external regulator from the wiring loom I am left with 2 wires. One is connected to the charge lamp circuit which includes the fuel pump relay coils and the other is switched ignition so the connection looks straight forward but it doesn't work properly. I am trying to maintain factory function and without modifying the core wiring too much.

The issue with the setup is the the charge light remain dim and the contacts in the fuel pump relay don't consistently switch and they don't switch with the same enegry or in other words the click is not as loud or strong. The voltage at the lamp wire on the alternator only rises to 5-6 volts where as it will rise to 12 plus if I connect it to positive via a separate globe. The other part of the problem is that if the fuel pump contacts do switch, they don't release when the alternator stops spinning like what occurs with the externally regulated setup further above. I have tested and it is charging but how well I don't know. Maybe good enough for the bench testing but not good enough for driving.

I have tried a few different ways to connect it but I am at a loss as to how I can connect an internally regulated alternator and maintain the factory function of the charge lamp and fuel pump relay. I can get the charge lamp to turn off but then the fuel pump relay wont switch and if I get the fuel pump relay to switch the charge lamp remains fully illumitated.

I believe the issue stems from the difference in how the charge lamp works for both alternators and how that fits withing the existing wiring of the vehicle. External regulator version does not require the lamp to even be in the circuit because the field is initially powered by the ignition circuit via the regulator not through the lamp like so many online articles show. Also the charge lamp will illuminate even when the alternator is completly removed from the circuit which I think is due to the ground connection through the fuel pump relay coils. Where as the internal regulated will not function unless the charge lamp wire is connected to 12V+ through the lamp and if the alternator is removed from the circuit so is the ground connection for the lamp and obviously it doesn't illumitate. I'm assuming I may have to use a relay that is only triggered when the alternator is making power to provide power to the coils of the fuel pump relay but then what do I do with the charge lamp and isn't that what the fuel pump relay is already doing? I have also wondered about a diode (don't recall which one) in the lamp wire at the alternator that only let power flow once a certain voltage has been reached but I don't think that will work either. I'm at a loss here.

Anyway, thanks for making it through all of that. I appreciate any feedback or information on how I can get this working.

Thanks from Australia.

 

I believe the issue stems from the difference in how the charge lamp works for both alternators and how that fits withing the existing wiring of the vehicle.

I would say that pretty much sums up the problem.

My initial thought is if you disconnect the relay and measure the lamp pin at the regulator while running it should match the battery voltage since there should be no current flow. I'm thinking the easiest way to go about it without making a huge change is going to be using a comparator connected to the lamp pin to determine if the lamp is on or off. The output of the comparator can then be used to power a relay that will turn on and off the power to your fuel pump and choke relay. Actually instead of the relay you can use a transistor to power your choke relay making it a little less bulky in the end.

If any of this makes sense and sounds like an option I can draw up something to help describe it better.

 

I would say that pretty much sums up the problem.

Thanks for the feedback. That is indeed the problem. But I had been looking at it all wrong. With the internally regulated alternator I had been taking voltage readings at the lamp wire on the alternator side when it was spining and reading +12V. What I had read online and also assumed an understanding was that the +12v was 'output' by the alternator lamp wire when the alternator was spinning, so +12v at both sides of the lamp therefore the lamp does not illuminate. When I connected the internally regulated alternator lamp wire to the vehicle lamp wire I had also assumed it was 'only' able to 'output' 5-6V which was not enough to energise the fuel pump relay. But the +12V or 5-6V readings was just the voltage of the circuit either through of the open circuit or after the globe in the vehicle circuit. Thats when it hit me that the internally regulated alternator is not 'outputting' any sort of power at the lamp terminal, it is completing the circuit for the warning lamp when stopped and then opening the circuit when producing power. It also provides initial start up field voltage through the globe too.

So on the vehicle side, the lamp wire requires a connection to ground when the alternator is not spinning and then 12V fed from the alternator side when the alternator is spinning so that the fuel pump relay coils are energised to switch contacts. And; as a result of 12V being at both sides of the lamp, it does not illuminate.

The internally regulated alternator requires initial voltage (through the globe to excite the field windings) and the circuit connection is opened once the alternator is producing power.

To solve the problem so far, I have used 2x 5 pin relays. The first relay has ignition at 85 and alternator lamp wire at 86. Initial field voltage is provided to the alternator lamp wire through the coil which also energises the relay at the same time. Pin 87 has Ground and 87A switched ignition. Pin 30 is the 'output' and connected to pin 86 of the second relay. The second relay has Ignition at 87, ground at 87A. Ground is also at 85. Pin 30 of the second relay is the 'output' that is connected to the vehicle lamp circuit wire.

When the car is switched to Ignition the first relay is energised providing a Ground connection at the 'output' pin 30. The second relay is therefore not energised providing a Ground connection 'output' to the vehicle lamp circuit which properly completes the circuit instead of through just the fuel pump relay coils. The dash board charge warning lamp illumitates bright. When the car is started and the alternator outputting power the circuit at it's lamp wire is opened which denergised the first relay which then providing an ignition 'output' to the second relay which energises it. The second relay being energised provides an ignition 'output' to the vehicle lamp wire circuit which powers the fuel pump relay and as a result of +12v at both sides charge lamp it can't illumitate and 'turns off'.

This all works. When the car is started the fuel pump and choke are powered by the start circuit and when the alternator is spinning, the fuel pump relay switches power to the ignition circuit and off again when the alternator stops, IE motor stopped, just like the factory intended. The charge warning lamp on the dash board also turn off completly and doesn't remain dim, partially lit or flckering. I can also make a short 'patch' connection to the new relays from the original external voltage regulator connector so I don't have to make to many changes to the wiring.

I first thought I could do this with a single 5 pin relay but it didn't matter how I connected it, the 'output' to the vehicle lamp circuit would be in the wrong state and was defaulting 'on'. It made sense on paper but not when connected. Even now when I'm writing this, It seems straight forward to do it with a single relay but it didn't work when I connected it.

The question I have now is. The lamp wire usually requires a globe which I presume provides some resistance for the field windings circuit. I presume the relay coil also provides some resistance? Out of curiosity, I have tested with only the relay coil in the alternator lamp wire circuit and it works but I don't know if that is doing long term damage. Will the globe and relay coil provide similar resistance in the alternator lamp circuit? Can I substitute the globe for the relay coil. Testing says yes but I don't know for sure?

Thanks.

 

What about using a PS64 3 terminal oil pressure switch, the 3rd terminal can power the fuel pump/choke relay, the alternator warning / exciter light can be wired as normal

 

What I had read online and also assumed an understanding was that the +12v was 'output' by the alternator lamp wire when the alternator was spinning, so +12v at both sides of the lamp therefore the lamp does not illuminate.

Something in your initial description gave me that impression.

Thats when it hit me that the internally regulated alternator is not 'outputting' any sort of power at the lamp terminal, it is completing the circuit for the warning lamp when stopped and then opening the circuit when producing power. It also provides initial start up field voltage through the globe too.

Glad you sorted that out. I like the relay idea better than what I was going to propose. It's actually simpler and when it comes to automotive stuff you are usually better to find a way to make commonly available automotive parts work. Otherwise you have to get in to load dump protection, transient spike protection, and other noise suppression.

 

What about using a PS64 3 terminal oil pressure switch, the 3rd terminal can power the fuel pump/choke relay, the alternator warning / exciter light can be wired as normal

I'm not familiar with that switch but I assume it switches based on detecting oil pressure. I hadn't thought about detecting the engine is running state via oil pressure. I guess that would work too and could also be a form of failsafe if oil pressure is lost while the engine is running. I was trying avoid adding too much to the factory setup but there might be other value I can get from a setup like that. It may also work quite neat with how and where the lamp and fuel pump relay wires actually run through the vehicle. I'll have a bit more of a look into it. Thanks for your suggestion.

 

Thanks for your suggestion.

No problem, what vehicle is it?

 

No problem, what vehicle is it?

It is a 1979 Holden Gemini station wagon. Known as a Opel Kadette C in Europe and I think Chevette in the USA. Fairly common vehicle at the time but harder to find them now and replacement parts can be difficult to obtain - at least in Australia. These aren't the idol car for restoration either, so there isn't many restoration parts being remade. I can't just go and buy it all new/remade, I have to do it, or most of it, myself. My plan is to restore/rebuild the parts to get it running first. Wiring, Engine, Suspension/Brakes etc and then it is a bit easier moving it around as I restore the rest.