XC60 Recharge T8 PHEV - secondary battery for fridge

[RKP]

Hi all. Recently updated to the XC60 Recharge T8 and now wish to fit the 12V secondary battery and charging control switch so that secondary battery only charges off alternator once the 12V starting battery is up to voltage (usual setpoint for the control switch is 13.2V, various models available from Auto car parts / 4WD outlets). The 12V secondary battery runs car fridge while driving, plus charges while driving when the alternator is running. When stopped for a few days, the secondary battery can be removed from the car to tent etc to keep the fridge going.

The 12V starting battery is in the rear of the car. Does anyone know the details of how to connect up the charging control switch to the XC60 Recharge T8? Are there any precautions related to the electric motor battery?

Here's a typical secondary battery control switch wiring detail
https://www.supercheapauto.com.au/bl...ls-wiring.html

[rhd443]

Originally Posted by RKP

Hi all. Recently updated to the XC60 Recharge T8 and now wish to fit the 12V secondary battery and charging control switch so that secondary battery only charges off alternator once the 12V starting battery is up to voltage (usual setpoint for the control switch is 13.2V, various models available from Auto car parts / 4WD outlets). The 12V secondary battery runs car fridge while driving, plus charges while driving when the alternator is running. When stopped for a few days, the secondary battery can be removed from the car to tent etc to keep the fridge going.

The 12V starting battery is in the rear of the car. Does anyone know the details of how to connect up the charging control switch to the XC60 Recharge T8? Are there any precautions related to the electric motor battery?

Here's a typical secondary battery control switch wiring detail
https://www.supercheapauto.com.au/bl...ls-wiring.html

I sincerely hope you aren't thinking of using a voltage sensing relay to do this, they are designed for cars with old style alternators, you need the DC to DC charger option on newer cars to do split charge.

Why don't you just look at a powerstation such as a yeti and charge it from the cigarette outlet which will only be active when engine or hybrid is online. Simplify your design

I have run a fridge from the lithium iron phosphate powerstations and have my dashcams wired up this way to remove any risks to the volvo electrical system.

[Philip Fisher]

Originally Posted by rhd443

I sincerely hope you aren't thinking of using a voltage sensing relay to do this, they are designed for cars with old style alternators, you need the DC to DC charger option on newer cars to do split charge.

Why don't you just look at a powerstation such as a yeti and charge it from the cigarette outlet which will only be active when engine or hybrid is online. Simplify your design

I have run a fridge from the lithium iron phosphate powerstations and have my dashcams wired up this way to remove any risks to the volvo electrical system.

Good point. You can only use a basic split charge relay with a normal alternator. Anything with a more complicated smart alternator needs a proper B2B charger. This is often explained in the motorhome magazines as motorhomes always used a split charge relay but now they are all Euro 6 with smart alternators they need to have B2B chargers for the habitation electrics.

Can you explain a bit more about the Yeti power-pack for the dash cam? Is it for the parking camera function?

[rhd443]

Originally Posted by Philip Fisher

Good point. You can only use a basic split charge relay with a normal alternator. Anything with a more complicated smart alternator needs a proper B2B charger. This is often explained in the motorhome magazines as motorhomes always used a split charge relay but now they are all Euro 6 with smart alternators they need to have B2B chargers for the habitation electrics.

Can you explain a bit more about the Yeti power-pack for the dash cam? Is it for the parking camera function?

Sure, it's basically a 12v dashcam setup I have, which runs from a lithium iron phosphate powerstation all the time, which is always powered from the cigarette socket in the boot.

I did this because I have contacts in main dealer motor trades who report they often reject electrical claims under warranty if you install a dashcam yourself (by tapping fuse boxes not using cigarette cables up front) because it's an easy get out for them. A bit like those who use tuning boxes on their diesels, which puts sensors out of range, and the cars ECU then flags the TB01 ECU code to get the technician to check for a disturbance to certain engine connectors, a tell tale sign they have been tampered after a tubing box has been removed before a warranty claim/service.

So I have a permanent dashcam power from the power station, and it does both parking and live mode, and doesn't impact the cars battery when parked. When you turn the ignition on, the cigarette socket wakes up, and it triggers live mode, when the supply to the cigarette socket goes off, the fail triggers a relay and tells the dashcam to go to parking mode.

Thinkware is one brand that uses a second positive cable that triggers parking mode (one permanent live, one switched) plus earth.

It's useful because the unit always stays topped up from the cigarette socket (charges quickly) and has USB and AC outlet sockets in the boot also. The power station has DC jack sockets for 12v output so you get a cable that accepts a cigarette for a fridge, or even solar input from PV panels if you wanted to use a 100w solar on the floor whilst camping to keep it topped.

https://www.goalzero.co.uk/products/yeti-200x

It's similar to this but a different model.

Hope this helps. Much easier to do with professional dashcams, not the 5v usb models from China 🙂

[RKP]

OK, after tips etc from above and hunting down Volvo in AUS about this, plus meeting up with an auto electrician, here's the deal:
* XC60 T8 drives and starts off the primary 400V battery in the front
* there's a 400/12V DC/DC converter to charge the Accessory (not starting) battery in the rear... tis runs the lights, entertainment, security, and accessory outlets (12V cigarette lighter sockets)
* you CANNOT connect anything to the power system in the car other than by using one of the 12V lighter sockets, USB outlets etc. If you do, the electrical management system will either reject it or break.... Volvo have had a few instances of people connecting dashcams and other minor loads elsewhere which have busted the electrical system
* Volvo in AUS don't know how much current the DC/DC converter pushes into the Accessory Battery, because Sweden won't tell them.
* Volvo Sweden response to the question about connecting a secondary battery charge arrangement (of any kind) was "not an authorised accessory"

The 12V socket in the back is 10A / 120W rated. That could power a low enough rated DC-DC converter to charge a secondary battery, BUT the charge current would be so low it would struggle to charge the battery meaningfully and run a fridge... as well as being fairly inefficient for energy use. Redarc do have a 6A 12v/12V DC-DC converter, which is set up to charge a battery in a trailer or similar, but at the moment I don't think it's worth spending nearly $500 on the bits and pieces to make this solution work on a very slow charge rate.

So my solution for the fridge problem is to run it off one of the 12V outlets directly (which works), and solar charge the battery separately. We will see how that goes.