Land Rover Old school Voltage regulator operation?

Andrew Technician Michigan Posted   Latest  
Resolved
Electrical
1972 Land Rover
Charging System
Voltage Regulation

So to be clear it's actually a 1978 Land Rover series II 88" just crazy there's not a listing for it.😁😁. I am dealing with a charging system issue

Got the vehicle and it was charging at 14.2 v for a while then after driving it dropped off and was at basically battery voltage gradually dropping down to maybe 11.0v or whatever the battery voltages were. I thought it was the alternator but it came back from the rebuilder and said everything looked great. I found the voltage regulator to be loose and hanging around. We replaced it due to it being quite rough looking but I still have charging system issues. Right now I'm dealing with understanding the voltage regulation circuit and trying to make heads or tails of the process of diagnosing it I took a couple pictures of it if someone has a good explanation to understand it a little quicker and more thoroughly that would be much appreciated.

Thanks Andrew

0
Paul Instructor
United Kingdom
Paul Default
   

Basically my understanding is that a bi-metalic strip creates an open and then a close in the circuit as it heats and cools. This creates an average voltage, much like a duty cycle (PWM). Sorry what I described is a general voltage regulator. I've just seen the picture and yours looks like it's a coil in there. So my description isn't relevant here.

0
Default Ð Awarded
Andrew Diagnostician
Michigan
Andrew Default
 

No problem, thanks for the thoughts 👍

0
Default Ð Awarded
Paul Instructor
United Kingdom
Paul Default
 

You're welcome. Athough basic, this website seems to offer some insight secondchancegarage​.​com/public/83​.​cfm

+1
Default Ð Awarded
Helpful
Andrew Owner/Technician
Australia
Andrew Default
 

I’ll try and give you a basic description. F terminal = Field. This is what is going into the alternator Rotor. The current is increased until the target voltage is reached. This is varied by the regulator. N terminal. This is half the voltage of the output. This output from the alternator tells the regulator what the charge rate is. It is also a good place to check that your rectifier is…

+2
Default Ð Awarded
Agree
Helpful
Andrew Diagnostician
Michigan
Andrew Default
 

Thanks for that helpful info. I checked out the wiring and it was pretty rough looking. So I repaired the wiring going to the F and N terminal on the back of the alternator. It seemed that there was good output now around 14.2V. After I continued to drive the vehicle i notice the gauge was reading below 12V again and sure enough it was not charging again. I checked the N terminal and found that…

0
Default Ð Awarded
George Owner/Technician
Alabama
George Default
   

This could be the regulator configuration....Without knowing the model of vehicle hard to look up....The series 11 88 listed has no meaning to me... Terminal ID: Stator (N)-Ignition (IGN)-Light (L)-Battery (B)Field (F)-Ground (E)

+1
Default Ð Awarded
Helpful
Andrew Diagnostician
Michigan
Andrew Default
 

Thanks for those pictures. I found that when the alternator is not producing voltage the N terminal show 0 V. Is that an internal alternator issue?

0
Default Ð Awarded
George Owner/Technician
Alabama
George Default
   

Could be internal ...could be you are losing (F) terminal voltage.....Check both terminals I would think that th (N) terminal is only for the light function .... - 1st I would disconnect the reg plug and apply B+ thru a lamp with enough current flow (at least 1 amp) .Let it run for awhile then check the (N) terminal. Should be 1/2 regulator set voltage (about 7 volts) Be sure that you also…

0
Default Ð Awarded
Helpful
Thanks
Mohammadu Diagnostician
New Zealand
Mohammadu Default
 

Andrew Jansen First of all check the alternator F= Field , when you touch the positive to field terminal it will spark like blue colour that mean it got a good brush and the alternator rotor coil and rotor is good N= Neutral is normally connected to stator winding. In your six pin regulator, when you turn back the regulator you got a resistor one side of the resistor you have to connect to…

+1
Default Ð Awarded
David Mechanic
United Kingdom
David Default
 

Andrew have you thought about replacing the Alternator for one with a built in regulator. This may be the reliable option or google Lucas voltage regulator and you should find the info required. Hope this helps regards Dave T...

0
Default Ð Awarded
Victor Technician
California
Victor Default
   

Hello, this is a real Land Rover. in the 80s those failed a lot for charging system issues: 1- alternator drive belt rpms were to slow in low rpm and ok at hi rpm. so, how is it doing? 2- this is the more likelly source of lack of charging. due to bad volt reg set up. the volt reg looks new so it might be super ok this is the "schemantic" instalation. check the pic. the volt reg you posted…

+1
Default Ð Awarded
Helpful
Andrew Diagnostician
Michigan
Andrew Default
 

Thanks Victor,

0
Default Ð Awarded
Andrew Diagnostician
Michigan
Andrew Resolution
 

This on is Solved guys. I appreciate the wealth of knowledge on this one. I ended up finding out that the two wires going to the alternator were crossed back through the harness. I would like to thank All of you guys for the insight on this one. I feel like the oldest technology can really stump me some times with out the right people to give insight..

0
Resolution Ð Awarded