P38A Mobiletron VR-VW010 alternator regulator.

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Why would the alternator on a diesel have a different set point to the petrol? It's the battery which cares, not the engine.

Don't know but all the diesels have the same alternator and the petrol changed around the time it went to Thor engine. Maybe they put more gadgets on requiring a bigger battery or maybe they realised they'd been a bit stingy with the original v8 battery and went bigger?

Either way, pretty sure MrGorsky went for the later Thor alternator when he replaced the original on his GEMS because it was bigger output.
 
Mobiletron VR-VW010 is the regulator you want, find it on Ebay

Datatek, I can find the regulator on ebay. Elsewhere you have said you have 2 P38s. How did you fit the regulator to the alternator?
On my P38 the alternator is Bosch (see picture).
Can the regulator be fitted to this?
 

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Datatek, I can find the regulator on ebay. Elsewhere you have said you have 2 P38s. How did you fit the regulator to the alternator?
On my P38 the alternator is Bosch (see picture).
Can the regulator be fitted to this?
Datatek, I can find the regulator on ebay. Elsewhere you have said you have 2 P38s. How did you fit the regulator to the alternator?
On my P38 the alternator is Bosch (see picture).
Can the regulator be fitted to this?
That is not the alternator fitted to the diesel so I know not if the VR-VW010 regulator will fit, As kermit said, you have to take the black plastic cover off to get at the regulator. If you get the regulator out, take some photos and I might be able to tell if the VR-VW010 will fit.
 
Why would the alternator on a diesel have a different set point to the petrol? It's the battery which cares, not the engine.
It's to do with the progressive changeover to Lead Calcium batteries, the V8 carried over from the Classic and was updated with the Thor engine to cope with demand. LR always like to use up old stock:rolleyes:
 
I'm not aware that the D+ line does anything other than provide the start up excitation current. ..... The regulator will function even with the D+ line disconnected, it only provides the initial excitation current

I am working from my experience, with car type alternators fitted to motorcycles (Moto-Guzzi, BMW R series (2 valve) and Triumph (Hinckley era).

On all of them I have experienced regulator failure, where a broken D+ feed results in minimal charge. Residual magnetism in the rotor means that charge happens, but because the field isn't being boosted by the regulator feed, it tends to sit at around (battery +0.2v). Which works with no real load and enough revs, but the system dies quickly with any load.

The Bosch generator on the Moto-Guzzi and BMW uses separate external regulator and rectifier assembles, and police spec regulator units with a higher set point are available and common retro fitments on heavily electrically loaded bikes.

The Triumph alternator is a ND unit with an integral regulator / rectifier assembly. Because of the compact size it costs over £100 and is only potentially interchangeable with a Suzuki / Kawasaki part from a single model, costing not a lot less. When mine blew the regulator, I looked at the schematics and mechanics and ventured £15 on an external regulator as fitted to the Guzzi. I insulated the alternator internal feed to the D+ terminal and substituted with a feed to it from under the seat, linked to the battery and switched live circuits. The result is a consistent 14.5v charge rate.
 
I am working from my experience, with car type alternators fitted to motorcycles (Moto-Guzzi, BMW R series (2 valve) and Triumph (Hinckley era).

On all of them I have experienced regulator failure, where a broken D+ feed results in minimal charge. Residual magnetism in the rotor means that charge happens, but because the field isn't being boosted by the regulator feed, it tends to sit at around (battery +0.2v). Which works with no real load and enough revs, but the system dies quickly with any load.

The Bosch generator on the Moto-Guzzi and BMW uses separate external regulator and rectifier assembles, and police spec regulator units with a higher set point are available and common retro fitments on heavily electrically loaded bikes.

The Triumph alternator is a ND unit with an integral regulator / rectifier assembly. Because of the compact size it costs over £100 and is only potentially interchangeable with a Suzuki / Kawasaki part from a single model, costing not a lot less. When mine blew the regulator, I looked at the schematics and mechanics and ventured £15 on an external regulator as fitted to the Guzzi. I insulated the alternator internal feed to the D+ terminal and substituted with a feed to it from under the seat, linked to the battery and switched live circuits. The result is a consistent 14.5v charge rate.
There is no current flow in the D+ line when the alternator is generating power, if there was the charge light would illuminate, the excitation current for the armature is supplied by the regulator once generation has started, varying the excitation current is how the output voltage is controlled. Residual magnetism has nothing to do with it except that in some cases there is enough residual magnetism in the armature for generation to start without the D+ line connected which is why you got a minimal charge with no D+ line.
 
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