Help Please. 24v warning light on and other stuff?

Hello
I am hoping that someone can let me know if I doing things the right way on my wolf 90 300tdi.
I am used to Series vehicles so having so much stuff under the bonnet is a bit daunting.

It’s a FFR 24V vehicle with twin alternators, two vehicle batteries under the seats and a load of wiring and junction boxes in the rear.

I have slowly been removing all the excess wiring, radio table etc from the rear. Radio batteries are long gone. So far so good.

The alternator (engine top left) which would have charged the radio batteries is very noisy so I suspect
The bearings are shot. The auxiliary alternator is driven by a belt off the crank pulley and goes via an idler wheel and adjuster wheel.

I have removed the auxiliary belt from the alternator and everything is nice and quiet again.

And finally the questions..

Now the belt is gone I guess it’s ok to just do away with the adjust and idler pulleys?

Understandably the 24v warning light is on in the cab. Is there a voltage sensor which needs
Removing to get the light to go out. If so any ideas where it is?

Any tips on removing the rest of the wiring?

Many thanks
Mark

Just be careful in removing the radio battery charging system. As you know each alternator supplies its appropriate set of batteries, but the systems are not entirely independent. When the voltage on one set of batteries drops below 23v it suggests that it's alternator cannot cope so the ECU switches the other alternator in parallel to help. The Electronic Control Unit is behind the passenger seat (RHD) & the relay midway in the engine bay close to the bulkhead.
Unless you intend to keep the vehicle until your dying day, there will be an occasion when you come to sell it. If majority of the fittings & wiring are still there it increases the value of the complete vehicle. From experience I can tell you buying replacement bits to retro fit a vehicle as it once was can be very expensive.

Hello
Thank you for reply and the good advice.

I do plan to hang onto it long term.

I think I may get the aux alternator refurbished and refit to keep the charging system complete.

the vehicle is completely standard as it’s just been released from the army and i don’t plan to
Add anything to it to increase electrical load. No additional lights or even a radio are wanted.

do you think the single alternator is sufficient for charging the two vehicle batteries?

with the cost of replacements being so high I also thought of keeping the refurbished alternator as
A spare in case the vehicle battery alternator fails.

regards
Mark

Mark yes one alternator should be sufficient as that's all you get with a GS. Mine was a GS 110 used by the RAF for airfield defence stripped down in a poor man's WMIK. It had radio batteries in the back but these were charged from a fused take-off from the vehicle alternator.

Being a radio amateur I wanted the radio batteries to be charged independently, so that when I had finished a transmitting expedition I hadn't flattened my vehicle batteries. Although the engine had the holes for the alternator bracket I had to purchase all the mountings & pulleys which was an expensive exercise.

Although I a few spare alternators some I rebuilt & one is new, it is nice to have the radio alternator fitted to be sacrificed if need be wherever you are. Of course you have to change the pulley & end cap connection. Apart from the RFI filtering electrically they are identical.

So a defender gs110 is 24v with just one alternator but your one came with 2 radio batteries,
2 vehicle batteries and one alternator?

just out of interest what amateur radio equipment do you use and do you use the military wing
Box aerials.

Yes all TUL(HS) & TUM(HS) whether GS or FFR are 24v.
The instrument panel & front part of the loom is the same, so although GS it had provision for upgrading to FFR role. I have a charge warning light for the radio alternator built in. The off side was modified for the breather tube for radio batteries (the original vehicle batteries don't need venting)

At shows I operate on 80m (3.5 MHz) with a Clansman TR-320 only using CW (Morse code) The other two bands again mainly CW 4m (70 MHz) & 2m (144 MHz) but that is with Jap radios.



My main interest, which I don't do at shows is 3cm (10 GHz)

Fantastic looking Defender

Hello again
I hope you don’t mind another couple of quick electrical questions.
On the bulkhead behind the seats there is a twin alternator control unit and a large fuse which I think is called a fast Fuse.

As I plan to have only the vehicle alternator I have disconnected the wiring from these.

One of the leads that was attached to the auxiliary alternator is still live with 24v. The wire
Is brown/yellow in colour. The vehicle alternator has two small wires that attach at spade terminals. One is brown/yellow as well and 24v live so I am guessing this is the link cable between the two and just needs to be disconnected at the vehicle alternator?

the other wire on the vehicle alternator spade terminals is green white but I have no idea where
That goes or what it powers..maybe part of the twin alternator link?

I don’t want to rip all the 24v wiring right out just isolate it and make it safe.

am I heading in the right direction here
Cheers
Mark

Just to quickly point some thing out in case others come across this thread in future.

uk military spec LR vehicles are voltages as follows.

90/110 - (TUM or TUL) GS are 12v only, FFR are vehicle 12v and add on seperate 24v for the radios (totally seperate from the vehicle electrics)

pre-Wolf defenders are same as 90/110

All Wolf (TUMHS and TULHS) are 24v vehicle and 24v radio and all integrated afaik

Mark, brown-yellow is the feed from the ignition circuit for each alternator that is fed independently through their respective ignition warning lights. It supplies voltage to the field winding to create a magnetic field before the alternator is revolving & then producing the magnetic field for itself a process known as "tickling".

If this wire was to touch earth the respective charge warning light would come on similar to the situation when connected to the alternator field winding. When the alternator revolves it creates it's own magnetic field & the voltage matches the voltage from the warning light supply. As there is no potential difference, the bulb reassuringly extinguishes.

To prevent the voltage now being generated from feeding a supply back up through the bulb & negating the operation of the ignition switch there is a blocking diode diode buried deep within the harness for each alternator.

The external differences between the alternators are the pulley grooves 7 for vehicle & 4 for FFR. At the rear of the FFR there are feed-through capacitors for interference filtering, one supplies the field & the other the main output.

The vehicle alternator has the very obvious main output, but two smaller terminals. One is for the field winding & the other is an AC output to drive the tachometer that feeds the control unit for EEGR fitted vehicles.

It is as well to remove the 150A fuse linking the two. It is not really a good thing to have an alternator running but with no load as the battery acts as a capacitor by absorbing high voltage spikes that may harm the diodes or regulator. So there is an argument that the belt to the alternator should be removed, on the other hand with no ticking voltage for the field winding there will be no alternator output. However it is possible to gradually build up an output from an alternator due to the residual magnetism of the ferrous parts of the alternator, so damage can result. Residual magnetism depends on how long the alternator was last used & is not a reliable way to run the alternator, tickling provides a reliable output straight-away.

The other argument for removing the pulley is that you are only going to wear out the bearings & brushes, on an alternator that is your spare. If you leave it in situ put some protective grease over the pulley to stop it rusting.

If you do swap alternators over, do not attempt to grip the pulley & use a socket on the retaining nut. It will be very very difficult to shift & you will damage the pulley grooves. Use a rattle gun & socket then it will meekly undo. The end covers & wiring are quite easy to swap over.