Thread: D4 Alternator

Hi DM, and your start-up voltage can be low for quite some time, I have had a few customers say their D4 did not start charging for well over 5 minutes after starting the motor.

But once it does start, the voltage will rise to a boost voltage of anything up tp 15.4v for up to 30 minutes.

Then your voltage will rise and fall with the load being put on the motor.

Accelerate and your voltage can drop to the low end of 12v.

Cruise or coast down hill and the voltage can go back up into the high 14v.

This is where problems occur with most ordinary battery isolators, they will either not cut in or will continually cut in and out as the D4’s operating voltage rises and falls.

Make sure the 2nd battery's negative cable attaches to the body rather than to the original battery's negative terminal.

Thanks Drivesafe for the advise. You said that normal dual battery controllers can be a problem, are there units that suit the Disco ?
I want to have power to run the Engel in the car and I tow a 20ft van with 100ah calcium battery and 186ltr Dometic 3way fridge, so keeping the 2nd battery system charged is important. I did have this DBS in my GU Patrol and it worked, but the Patrol couldn't tow 1/2 the load te Disco does
Other problem is most days I drive 15 min to work so not much is getting charged !

Regards
David

Hi Graeme
I have attached the earth lead to the earth stud in the engine bay.
I got that of the forum when I was installing the system.

Thanks
David

Originally Posted by DM Disco

Other problem is most days I drive 15 min to work so not much is getting charged !

Hi again and this includes your cranking battery.

As Graeme posted but also make sure they have not earthed your isolator to the neg terminal on the cranking battery.

What type and where is your auxiliary battery mounted?

Hi Drivesafe, the Aux battery is an Optima yellow top 55ah AGM and is mounted under the bonnet in front of the main battery. The earth on the second battery is connected to the earth stud on the inner guard in front of the main battery box. The Pos comes from the main battery to the dual batt controller then to the Aux batt, also off the Aux batt Pos is the cable to the Anderson plug. The Anderson plug neg is to an earth stud in the rear.
The control wire for the trigger wire for the dual batt controller is from a spare fuse slot in the engine bay.

Regards
David

Originally Posted by DM Disco

The control wire for the trigger wire for the dual batt controller is from a spare fuse slot in the engine bay.

Why does it have a seperate trigger wire and why isn't it connected to the main battery positive supply?

Hi Drivesafe, the trigger wire has to be from a power source controlled from the car accessories circuit so it isolates the controller and Aux battery when the car power is off to protect the main battery.

Rewards
David