Thread: Beware Charging Dual Battery in D4.

Hey Drivesafe,

Hope you're still reading this post....

Can you recommend a fitter of your systems in BrisVegas? Preferably on the northern side (I'm in Wavell Heights).

Thanks,

Michael

googlemaps has me a little over an hour away, if you cant get someone closer I'll fit it up for you,

Just make sure that you have the security codes and sequences written down for everything before you go getting it fitted.

Originally Posted by Blknight.aus

............ if you can't get someone closer I'll fit you up..................

Very kind of you Blknight.

Hi Michael, if you take up Blknight’s offer, make sure you do half the work. That way you’ll learn for yourself.

Hi Blknight and don’t worry about the security codes, thank god, they are now a thing of the past in MOST new vehicles.

Originally Posted by Duck's Guts

This weekend I went camping about 3.75hrs drive each away (combination of tar & dirt, 40-110km/hr, steep hills & long flats, i.e. all terrain covered).
I plugged a digital volt meter into one of the accessory plugs near the D4's transmission lever. The voltage observed only ranged between 13.74 & 13.86V, now matter whether accelerating, braking, coasting, idling, or doing anything else. With the engine off I got a voltage of 12.6~12.7V.
So, either the accessory plug supply is regulated during alternator charging, or I'm getting very different results to Roamer.
I'm confused, can anyone shed some light?

Diagnostic menu on sat nav reports the same: constant 13.7-13.8V with engine on no matter what type of terrain/driving, and 12.6-12.7V engine off.

Originally Posted by Duck's Guts

Diagnostic menu on sat nav reports the same: constant 13.7-13.8V with engine on no matter what type of terrain/driving, and 12.6-12.7V engine off.

Thats strange , my voltage does vary , even just with slight acceleration not much 14.4v down to 14v, and down to 13.7 with heavy accel. However I do think my main battery is suspect (always has been), maybe its trying to charge battery up. PS I have unplugged fridge to make sure there is no draw.
Does yours not run up to 15.4v just after start for abit ?
Cheers Ken

I won’t say the you won’t get readings down to 12.7v or lower, but I have not seen them that low and like others, the lowest I can get my D4’s voltage to is 13.6 ( got 13.2v a number of times on the D3 ) and even at this level, during tests, I was getting 64 amps going into three batteries ( total Ah of 265 Ah ) located in the cargo area and managed to raise the batteries from 50% Soc to over 85% Soc in just 2.5 hours of driving.

There can be a number of causes for low voltage readings and the point where the D4 takes it’s readings from will govern the accuracy of any voltage reading.

I don’t know the exact reference point the D4 uses, but most vehicles take their voltage reading from the power supply wire going into the ECU.

This will meet all the requirements for the vehicle’s management system but is no true indication of the voltage level at the cranking battery. This is the voltage we need to know to be able to determine whether auxiliary/house batteries are going to charge.

When the voltage is monitored elsewhere in a vehicle, if there are any other devices switched on, such headlight, sound systems, air conditioning and so, if these devices are on at the time the voltage readings are being taken, they WILL cause a significant voltage drop on the supply wire to the ECU.

The ONLY way to get an accurate voltage reading is to measure the voltage at the cranking battery’s terminals.

Originally Posted by drivesafe

Hi Michael, if you take up Blknight’s offer, make sure you do half the work. That way you’ll learn for yourself.

Hi Blknight and don’t worry about the security codes, thank god, they are now a thing of the past in MOST new vehicles.

He'd actually wind up doing most of it, I'd just make sure he didnt pooch anything or let the smoke out... Bugger of a job getting it back in.