• Welcome to the Land Rover UK Forums

    You are currently viewing the site as a guest and some content may not be available to you.

    Registration is quick and easy and will give you full access to the site and allow you to ask questions or make comments and join in on the conversation. If you would like to register then please Register Now

Alternator and D+ terminal voltage and split charge

Ginyons Kernow

Ginyons Kernow

Accelerating Away
Hi folks,

Defender 1997, 300tdi. OK I know on the back of the alternator that the B+ is the main charge output to battery, and that D+ is another +ve feed that switches the dasboard battery light off after ignition. And also that the W connector is for a tachometer if fitted.

The previous owner fitted a split charge system and has wired a separate wire from the D+ alternator terminal to the relay which makes sense - when the alternator is operating this activates the split charge relay to bridge the two batteries. With the vehicle running I have just tested the voltage between B+ & chassis and also D+ & chassis. The B+ (as expected) reads a steady 14V which is presumably the voltage regulated current to the battery. However the D+ to chassis measures beween 19 and 22V (at idle speed).

So my questions:

  • The split charge relay is knackered but the previous owner had it replaced jsut two months ago. I'm wondering whether the ~20V is too large for the 12V/100A relay (Nagares manufacturer). I guess the question is what voltage range can the switching coil in the relay handle? Maybe this 20V is why the relay keeps going if its designed to run on 12V?????
  • Should the D+ be this higher voltage? If so should I buy a relay whose internal coil operates on a larger voltage range?
  • Slight aside: Given this model has no tachometer why on earth is there still a white/black wire coming off the W terminal on the alternator? Surely on my landrover this W connector isn't used or required whatsoever?
Thanks again.
 
Interesting note in the pdf link on battery sensing setup on 300tdi's.
Mobilecentre - I am thinking of getting one of the VSRs ddesigned for marine applications (BEPmarine) which look good.

That said I have just reposted anothe rpost as I found out today that when running at 2500rpm the voltage across the starter battery is nearly 17V which implies the regulator on the alternator has ******ed.

Any further thoughts anyone?
 
Yes does sound like you have other issues to be addressed. The small VSR can be used to switch an existing larger relay. You could use a remote regulator / charge controller and feed both batteries from the one alternator or put a larger VSR in. All the way up to one of these

7622.jpg
 
Back
Top Bottom