Thread: What happened to your D3/D4 today?

Originally Posted by BradC

So went for a long drive today. When settled, my old alternator used to sit at 13.7V. If it was really warm (>40C) that'd drop 100mV and if it was really, really cold (<5C in Perth) it'd come up 100mV. Maybe even as far as 13.9V when it was close to zero. Today it's oscillating between 13.9 and 14.0V on the IID, verified with a meter. When I put it in it was at 14.0. I figured maybe the EMS though the battery was flat and needed a kick while I did a lap of the block. Today I took it for a ~50k run. It would always settle at 13.7 on the nose. Maybe +/- 50mV on the meter.

I'm perplexed. If it was a new alternator entirely I could maybe understand a difference in the regulator, but I swapped the regulator to the new one. Where has the extra voltage come from?

Hi Brad, what do you mean?

Also, what is the highest voltage you see?

Originally Posted by drivesafe

Hi Brad, what do you mean?

Also, what is the highest voltage you see?

I don't recall seeing more than 14.1V and that was on a zero degree day.

What I meant was if I got in the car on an average day (15-35C) and drove for ~ half an hour I would see a steady 13.7V on the meter and IID. It has been like that since I bought the car in 2017. The IID would report a voltage set point of ~15.1-15.5v but it always sat on 13.7.

Under the same conditions with the new alternator I now see about 13.9-14.0V. So I've got an additional 200mV. Set point / load / temperature is the same, as is the voltage regulator on the alternator. I just wonder what else influences the voltage output. I did wonder if it was temperature. The old unit was seriously clagged up with debris, and I wonder if that made the reg run hotter.

Anyway, it's not important but it is somewhat perplexing.

I would routinely see 14.8-15 volts within a minute of startup on a zero degree day, voltage will stay at that for 20-30 minutes.

That's on either alternator I've had in it.

Is there a locally available good quality all filters service kit, Mahle or equal for the 2.7D?

Originally Posted by BradC

I don't recall seeing more than 14.1V and that was on a zero degree day.

What I meant was if I got in the car on an average day (15-35C) and drove for ~ half an hour I would see a steady 13.7V on the meter and IID. It has been like that since I bought the car in 2017. The IID would report a voltage set point of ~15.1-15.5v but it always sat on 13.7.

Under the same conditions with the new alternator I now see about 13.9-14.0V. So I've got an additional 200mV. Set point / load / temperature is the same, as is the voltage regulator on the alternator. I just wonder what else influences the voltage output. I did wonder if it was temperature. The old unit was seriously clagged up with debris, and I wonder if that made the reg run hotter.

Anyway, it's not important but it is somewhat perplexing.

Does that just indicate your old alternator was never up to scratch, 14 volts or just over is always the best charge rate

Originally Posted by shack

I would routinely see 14.8-15 volts within a minute of startup on a zero degree day, voltage will stay at that for 20-30 minutes.

That's on either alternator I've had in it.

These are more like the voltages I would expect to see in a D3.

D3s have an "intelligent" variable voltage alternator operation.

Toyotas have a standard Variable Voltage alternator but a D3 took the standard Variable Voltage operation and added a few monitored functions used to determine what voltage the alternator will operate at.

When you first start the motor, for exactly 30 seconds, the D3 monitors the state of the cranking battery.

It then, based on the findings of this initial 30 second monitoring and the ambient temperature, sets the voltage the alternator will operate for the next 30 minutes.

This is for the first start of the day. If you stop and the start again, the higher voltage is only for the next 10 minutes after the second and any additional starts for that day.

The highest voltage I have ever seen in Australia , is 15.1v, but I had a customer in Canada, who, after fitting one of my isolators, was not able to charged his auxiliary battery on the way to work. But coming home in the afternoon, all was fine.

He lived and worked up in the Arctic Circle and he monitored his operating voltages and found that his alternator operated at 15.5v during his morning run.

At the time, my Traxide isolators had an over voltage shut down set to 15.2v.

A modified chip with an over voltage shutdown set to 15.6v, was sent to him.

All worked perfectly after the chip change.

Originally Posted by discomatt69

Does that just indicate your old alternator was never up to scratch, 14 volts or just over is always the best charge rate

At first glance that makes sense, but it doesn't make sense electronically. Mine is a stock D3 with stock electrical loads. When I add additional loads from the caravan the voltage didn't drop, so it's not like the alternator was struggling. Anyway, different now. I'll watch it over the next year or so and see how it performs at those temperature extremes.

Originally Posted by Saitch

Hopefully, ready this coming week. Just over one month from drop off.

So, five weeks and quite a few bob later, the D3 is home and gearbox all better. After not driving it for nearly five months and driving the old Tojo 'tilly and my wife's Kia Cerato, I must say how pleasurable it was to get back in the Disco! Nothing wrong at all with the Kia. A great car, really. I just can't get comfortable with the concept of my arse being about four inches above the road.