Charge voltage after startup

Seems to be normal, I have a 100 series and it does the same, I asked an Auto lecy about it and he said the voltage stays down for a while because the glow plugs do not shut off immediately the engine starts.

I had an HJ61 Turbo with the intake heater and not glow plugs.
When starting it would sit at around 12v with engine running and only rise slightly if, if, revved but hardly moved up at all.
When the heater time out was finished or the water temp was then sufficient in the block sensor, the system would then switch off and suddenly voltage would go from around 12/perhaps under 12 to 14, as the heater load was switched off.

Because the HJ60 has a smaller alternator output than a HJ61the voltage will stay low unit the time out period ends.

The HJ60 is around 45amp alt or 60amp, not sure never tested the output, while the HJ61 had an alt which would go better then 100 amp output so the "on heat" running voltage will be lower than the 61.

Sounds a bit odd to me. Maybe slightly different for other models. My 1HZ engine would drop when cranking but as soon as the engine fired up the voltage would begin climbing to 14+ volts almost immediately. I know the glow plugs stayed on for some time because of emission requirements, or so I was told. The 1HD-FT engine that now inhabits the engine bay starts fine on the coldest mornings where we are so I have never bothered to connect the toaster element in the intake manifold.
I guess if it ain't broke don't fix it. If it's been like that for the last 18 years and starts ok.

Cheers
Pop

I think that you will find that the voltmeter is connected to the ignition circuit 'downstream' from the battery and is reading the voltage where the heater or glow plugs are causing some voltage drop in the wiring. The voltage at the battery terminals is probably somewhat higher than you are observing. Even so, 8 volts seems particularly low and I suspect the voltmeter lacks accuracy at that reading point.
With a multimeter you could check directly at the battery terminals.

The typical alternator would be capable of holding the battery at 12 volts or higher even with glow plug load, rising to about 14v eventually.

Hi
8V does seem a little low & hopefully is not the true battery voltage
That would be my first check, with a multi meter ,check voltage DIRECTLY on the BATTERY terminal poss[not on the connecting lug]

If it is 8V , with just the glow plug /manifold heater it is quite possible the battery is sick, lost capacity due to age or abuse
Next check would be heavy a load test on the battery

If the battery Voltage is much higher than 8V , you could have some bad /dirty connections between the battery & the voltmeter[voltage drop under load.]
To find that you need to check voltage progrresively from the battery to the point where the meter is connected
A likely area is the actual battery connections, followed by the MAIN neg to chassis connection
PeterQ

Diesels do have an after glow temp dependent delay relay,depending on the engine block temp, that could hold in for some time.

Thanks everyone for your comments. I have never looked at it after startup before so dont know if that is normal or not. Anyway I have just driven the vehicle and noticed my ctek controller for aux. battery is showing a fault and the voltage dropped right down into the red and stayed there for quite a whilebefore jumping straight up to 14.Starter cranked effortlessly and started no heaters so I guess its off to the electrician to find the bad connection if I cant. I will start with the battery terminals as suggested first.