Thread: Beware Charging Dual Battery in D4.

Originally Posted by Duck's Guts

Is it possible that the 2.7 & 3.0 have different charge control systems?

That's quite possible because as far I could establish, nothing on the MY10 2.7 engine was changed from the MY09 2.7, not even upgrading the a/c compressor to the 3.0 version to stop it pumping when not required.
New alternators and starter motors were sourced for the 3.0 too although that could have been only to do with better waterproofing.

Originally Posted by outbacktourer

Just found the diagnostic screen and checked the volyage on a trip to the city and back. Sure enough, charges only when coasting/brakeing. At other times 12.7-12.8V. Mine is a 3.0L

OBT

Hi OBT, my readings are from 3lt, when you say only charges when coasting\ brakeing, what volts is it then. Tim may be able to correct me, but I think ya need around 14.4v to give battery a decent charge.
Cheers Ken

Hi Roamer, if a battery is low, say at 12v, you can charge it with as little as 12.2v and this is how both battery chargers and DC-DC converters work.

As long as the voltage being applied to the battery is higher than the State of Charge of a battery, no matter how small the difference, the battery will charge.

the D3 fully charges batteries with as little as 13.2v.

The advantage of having high charge voltages, such as 14.4v, is that the battery will fully charge sooner.

I have a lot of testing ahead of me where the D4 is concerned but this relates to the time required to charge batteries, no whether auxiliary/house batteries will charge.

There are well and truly enough D4s now out there, equipped with my DBS to show my DBS work.

Again, there is a need to get voltage readings at the cranking battery and not relying on the data being displayed in the cab.

Any voltage readings taken anywhere other than at the cranking battery terminals, is going to be erroneous for the data that is needed to determine whether there is suitable voltage levels for charging batteries and not just the cranking battery but any batteries connected to the D4’s electrical system.

If anybody is interested in setting up their D4 to get some accurate voltage readings at the cranking battery, I can show you how to set up a crud, cheap but accurate wiring connection to do so.

Hi Tim, thanks for info, do you think the D4 may be able to act like a battery charger (ie, different stages of charge, and or temp variation) hence all these different readings.
My DB system works a treat,and thats a 55ah in car and 315ahr in van (does have solar, which I guess would back feed to charge all batteries including crancking )
I will set my meter up off cranking battery, and check out differences between the two. (you haven't seen crude till ya see what I can do)
Cheers Ken

Originally Posted by roamer

Hi OBT, my readings are from 3lt, when you say only charges when coasting\ brakeing, what volts is it then. Tim may be able to correct me, but I think ya need around 14.4v to give battery a decent charge.
Cheers Ken

It's in the 14-15's. I'm going for a run to bathurst today and go to school on it and report back...

OBT

Originally Posted by outbacktourer

It's in the 14-15's. I'm going for a run to bathurst today and go to school on it and report back...

OBT

As per previous findings the charging is occurring while coasting. Voltage when charging is around 14.7 +- .1 Static voltage (when under power) does move around a bit. I saw 14.2 at one point (after a fair bit of stop-start motoring) but mostly low 13's and 12.7 was the lowest (and most common). 2010 3.0 TDV6

OBT

Does anyone know what the MOST FOT temperature reading is in the secret vehicle readings screen is from?

BarryH

What does FOT stand for?