Thread: D4 Alternator

Originally Posted by drivesafe

Just idling in the driveway is no indication of whether your alternator voltage is OK or not.

I cannot believe the charging system is working properly to only have 12.2V to 12.4V at idle (ie not charging at all) for just a minute or so, let alone for 15 minutes, even if it charges at 15V at higher revs on engine overrun.
Since fitting my dual battery LED status monitor I've been able to see that my vehicle always starts charging within 2 seconds of starting the engine. Any time my aux battery has been 12.3V or lower, as indicated by a particular LED on the monitor, I've seen its voltage rise the moment the main battery voltage rises above 12.3V, indicating that the voltage has exceeded the VSR cut-in voltage of 13.7V. My battery monitor uses dedicated power wires direct from each battery so no distorted voltages due to voltage drop.

Originally Posted by DM Disco

I plan to get a voltmeter that can monitor both batteries. So I can get a better ideal of what going on

Hi David, if you are out to sort out whether you have a problem with your alternator, just set up a digital multi meter as I posted and if you find you have a problem with your charging, get your dealer to fix but under normal use, volt meters are next to useless.

If you are having so much trouble that you need a volt meter to keep track vehicle’s charging, it’s time to get the vehicle fixed but other wise, volt meters tell you very little about your batteries condition or state of charge.

Save your money and spend it on something that actually gives you some genuine benefit.

Hi David

I'm with Graeme on this your systems not normal (right)

Loading up to go away last couple of days and just got the "start motor battery low" signal

Started up and goes straight away to 13.7V (got touch screen) at idle, lift revs to 1000rpm and it goes to 14.6V, so seems like you have a problem,

I have a traxide dual battery system and did notice the neon flashing a day earlier which meant the cranker was going down then and the traxide had isolated itself (I think at 12.3V,, Tim can confirm )

Take it to your dealer they will sort it out for ya

PS
I have a KK with 320ahr batteries, and an Optima 55 in car (3lt), all worked great since new (Nov 09) on Traxide (in fact the Traxide was on my D3 for 3yrs first)

Cheers Ken

David,

I went through all the problems you are having when i installed a second battery system in my D4. The voltage moves all over the place in the D4. I did an outback trip and cruising on long flat roads the car would happily sit at 12.3 volts and therefore no charge to the second battery through the isolator that was waiting for more than 12.7.

I know drivesafe has other views which he will express. I converted to a dc to dc charger and other than slower charging time, i havent had a problem. Have a look at the Redarc website. There is also a long discussion on this forum as i tried to work all this out. Search for "beware second battery system" to find it.

Peter

Hi all,
A friend of mine has done a bit of research on my problem with the alternator and found the D4 3ltr diesel has a " voltage sensing, charge on demand alternator". Which means that when a second battery is connected via a dual battery controller that direct connects batteries the electronics seen the voltage of the second battery and can confuse the #*%# out itself. The alternator is designed to help save fuel /emmissions by only charging when the battery needs it, our when coasting. As I have an AGM optima second battery which hold a higher voltage than the cranking battery the system thinks its OK . Thats why my low battery light came on at the drive-in last week and I had to run the car for a while or it indicated it would shut itself down.(15-20min into the movie)
Peter's last post has my answer, a DC/DC charger for the second battery, as the alternator won't seem the second battery, just a load on the main battery therfore needing charging, I hope. This charger will also isolate the main battery to protect it.
I have fitted a parahna dual volt meter and when the dual battery system is connected the charging seemed eratic but when I disconnected it the system is charging how it is supposed to, as my mate Dave explained (he found info on a US site).
The alternator on te 3ltr diesel is supposed to be different to the D3 and 2.7ltr D4.
I am heading to Pirahna on Monday to run this by then and get a DC/DC charger system either Redarc or Ctec.
If I was running a fridge or some continious load that was drawing down the second battery my system may have worked better.
I will also put a DC/DC charger in my caravan this will protect all the batteries and help them charge properley as they are all different types,lead acid,AGM and calcium.


Hopefully this will solve my problem.

Reards

David

My redarc dc to dc charger works well.
I use a piranha battery monitor and voltages are stable on both batteries.....second battery slightly higher than the starter.

Hi Disotwinturbo, where did you mount your unit, I have my optima AGM mounted in front of the main battery so there's not a lot of space left.
The Piraha controller is on a vertical bracket in front of the Optima battery.

Regards

David

Originally Posted by DM Disco

As I have an AGM optima second battery which hold a higher voltage than the cranking battery the system thinks its OK

My aux battery is also AGM (not Optima though) yet my 3.0's voltages don't reflect yours. The 3.0's ecu-controlled charging is old news to a lot of people. I await reading about the outcome of a visit to your dealer.

Edit: Does your main battery charge properly if your aux battery is left disconnected for a few days?