VF Calais V8 battery voltage drops to 12v when powering a caravan fridge

[vf2calaisV8]

I was occasionally towing a 2015 Jurgens Lunagazer with my May built 2013 VE Series 2 SV6 Z-Series red hot sedan, until I got rear ended on my way home from a tax appointment in October 2023 and the car was declared a statutory write off by Shannons Insurance as the towbar bent 2 chassis rails when being hit by a Jeep at nearly 70km/h.
However the VE kept the battery voltage above 14v the entire time, unlike my '08 60th anniversary VE that had the battery draining issue, and kept the fridge running in the Lunagazer for the entire trip.
I've since purchased my 2016 VF Calais V V8, it and my Dad's 2016 VF SS will drop the voltage to 12v when the battery is charged, and the caravan's fridge turns off when the voltage drops below 14v as it thinks the car isn't running so it doesn't drain the battery
Is there a way to get the VFs to constantly output 14v when towing?
The car is aware it's towing as the merging indicator flashes 6 times instead of 3, and revs higher before shifting gears. It has a genuine holden 2100kg towbar I bought from the wreckers 2017 VF SV6, with a genuine wiring kit I bought on Ebay.
The fridge is powered by an anderson plug, attached via a relay directly to the battery in the boot. The relay is turned on by the accessory connector behind the glovebox, which also powers the electronic brake controller, but only when the car is turned on. It does not come on when remote starting, until I get in the car and press start/stop. This setup was all pulled from my written off VE.

 

[Crunchy Granola]

I was occasionally towing a 2015 Jurgens Lunagazer with my May built 2013 VE Series 2 SV6 Z-Series red hot sedan, until I got rear ended on my way home from a tax appointment in October 2023 and the car was declared a statutory write off by Shannons Insurance as the towbar bent 2 chassis rails when being hit by a Jeep at nearly 70km/h.
However the VE kept the battery voltage above 14v the entire time, unlike my '08 60th anniversary VE that had the battery draining issue, and kept the fridge running in the Lunagazer for the entire trip.
I've since purchased my 2016 VF Calais V V8, it and my Dad's 2016 VF SS will drop the voltage to 12v when the battery is charged, and the caravan's fridge turns off when the voltage drops below 14v as it thinks the car isn't running so it doesn't drain the battery
Is there a way to get the VFs to constantly output 14v when towing?
The car is aware it's towing as the merging indicator flashes 6 times instead of 3, and revs higher before shifting gears. It has a genuine holden 2100kg towbar I bought from the wreckers 2017 VF SV6, with a genuine wiring kit I bought on Ebay.
The fridge is powered by an anderson plug, attached via a relay directly to the battery in the boot. The relay is turned on by the accessory connector behind the glovebox, which also powers the electronic brake controller, but only when the car is turned on. It does not come on when remote starting, until I get in the car and press start/stop. This setup was all pulled from my written off VE.

Jurgens Lunagazer ?. Take the lot down to a good auto electrician.

 

[vc commodore]

Must be something to do with the car colours

 

[07GTS]

if the fridge is direct to the batterie then the ecu wont sense the load, the power is fine but the earth has to be after the sensor on the earth wire, if u use the same chassis earth that the battery is connected to then it will see the extra load on the circuit and should adjust charging accordingly, or try turning the headlights or parkers on may cause it to keep a higher charge, there are some alternator settings that tuners can adjust but i doubt they do much with them to understand them as its not usually adjusted and they arnt simple voltage related settings so alot of test and see results and test again and see what it does sorta stuff

 

[vf2calaisV8]

if the fridge is direct to the batterie then the ecu wont sense the load, the power is fine but the earth has to be after the sensor on the earth wire, if u use the same chassis earth that the battery is connected to then it will see the extra load on the circuit and should adjust charging accordingly, or try turning the headlights or parkers on may cause it to keep a higher charge, there are some alternator settings that tuners can adjust but i doubt they do much with them to understand them as its not usually adjusted and they arnt simple voltage related settings so alot of test and see results and test again and see what it does sorta stuff

Thanks, I'll double check how the earth is wired
I'm somewhat reluctant about going straight to an auto-electrician or tuner because that might get expensive if they have to work out something new that they've not had to do before
I probably should've explained in my first post, the Jurgens Lunagazer is a 24ft Caravan including the drawbar, the lightest caravan of that size we could find that the commodores could tow. With a tare mass of 1763kg, and an atm of 2163kg, we just make sure to not fully load it and keep under the maximum towbar weight and ball load, verified with a public weighbridge. The commodores and calais have been amazing towing cars, but the VE successfully powered the fridge the entire time unlike the VFs so far.
Perhaps I need to install a subwoofer to increase the power load to get the alternator running

 

[07GTS]

or u may be able to get a 14v converter/booster so it just powers the fridge all the time at constant voltage no mater the vehicle voltage could be worth seeing a 4wd place im sure they will have a solution for that sort of stuff

 

[Lex]

I was occasionally towing a 2015 Jurgens Lunagazer with my May built 2013 VE Series 2 SV6 Z-Series red hot sedan, until I got rear ended on my way home from a tax appointment in October 2023 and the car was declared a statutory write off by Shannons Insurance as the towbar bent 2 chassis rails when being hit by a Jeep at nearly 70km/h.
However the VE kept the battery voltage above 14v the entire time, unlike my '08 60th anniversary VE that had the battery draining issue, and kept the fridge running in the Lunagazer for the entire trip.
I've since purchased my 2016 VF Calais V V8, it and my Dad's 2016 VF SS will drop the voltage to 12v when the battery is charged, and the caravan's fridge turns off when the voltage drops below 14v as it thinks the car isn't running so it doesn't drain the battery
Is there a way to get the VFs to constantly output 14v when towing?
The car is aware it's towing as the merging indicator flashes 6 times instead of 3, and revs higher before shifting gears. It has a genuine holden 2100kg towbar I bought from the wreckers 2017 VF SV6, with a genuine wiring kit I bought on Ebay.
The fridge is powered by an anderson plug, attached via a relay directly to the battery in the boot. The relay is turned on by the accessory connector behind the glovebox, which also powers the electronic brake controller, but only when the car is turned on. It does not come on when remote starting, until I get in the car and press start/stop. This setup was all pulled from my written off VE.

I thought there was a setup in the bcm? that needed to be turned on for towing?

 

[stooge]

smart alternators cause those types of issues, modern 4wd vehicles have the same problem.
talk to someone that specializes in fitting aftermarket electrical systems to vehicles and they should be able to advise what product to use.

 

[wetwork65]

Not that I'm adding value to the voltage issue, but that caravan looks very big for that car in the photo. And there looks to be too much push down weight at the towbars, judging by the back wheels.
Mind you I've seen 4WDs being pushed down to a more extreme angle by what they're towing on the highway. To the extent that I wonder how they stay in control.

 

[lout]

https://www.amazon.com.au/KNACRO-DC-DC-Converter-9-14V-Supply/dp/B07BDCD9DY