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Fault Finding and A Failing Fridge

Aside from building reliable custom off-grid battery systems, we specialise in fault finding and resolving defective battery installations, so our clients can relax and enjoy their travels.

John was having problems with a lithium battery system not functioning correctly and a three way fridge which was not working on 12 volt power from the car, so he bought in his Jayco Journey caravan and Isuzu MUX for inspection.

The caravan had been fitted with a 100Ah lithium battery and a Victron Smart Shunt 500A Bluetooth battery monitor, so information about the battery could be read from a smart device.

Unfortunately, the Shunt had not been programmed correctly to the system, so John was seeing inaccurate battery State of Charge (SOC) information.


We discovered why the battery was not receiving power from the vehicle, thanks to a blown 20A blade fuse on the Redarc BCDC1225D. Now...

  1. A fuse should not have been attached to the BCDCiside the caravan, but located at the vehicles' battery.

  2. The blade fuse was blown because it was too small, both in size and amperage, to handle high current.

  3. A Blade fuse is the incorrect type of fuse. A MIDI fuse (ANS) should have been used, and

  4. The BCDC vehicle input wiring was too small anyway.

On the other side of the BCDC, it was wired directly to the lithium battery, without a fuse. So in the event of a fault with the BCDC or wiring, the unit could catch on fire!

Incidentally, no fuse, no insurance.

John's caravan also sported a 160W stick-on solar panel on the roof, which thankfully had been installed with an air gap to help efficiency in the heat. This panel was connected to the BCDC solar input.  More on this in a bit...


Looking further, we identified the caravan was not receiving 240V charge, due to a damaged and dead Victron IP65 15A 240V Charger.

The caravan trailer plug had a 12V Power Feed (commonly known as a 'hotwire'), on Pin 2, which was connected to the Breakaway Unit (an emergency breaking system if the caravan becomes disconnected from the vehicle), to charge the internal battery of the Breakaway Unit. The Power Feed was also connected to the van's power supply as auxiliary charge.

The problem here is, Pin 2 on the vehicles trailer socket was connected to the reverse wire, so when John put the vehicle in reverse, it would try to charge the lithium battery in the caravan and blow the vehicles' reverse fuse!

The 15A three way fridge had a Vibration Sense Relay Switch, which we found to be faulty. This is supposed to turn the fridge on when the van is moving. To top it off, the fridge wiring was wired to the 12 pin plug, but the vehicle's 12 pin socket didn't have any wiring in sockets 8 to 12, so there was no power getting to the fridge.

Heck, lets face it. The fridge had no chance!


Righto. Now to make good.

We removed all incorrect wiring, rewired the battery and Smart Shunt and installed the appropriate ANS battery fusing. 

We removed the undersized wiring & relocated the BCDC and installed the appropriate ANS fuse for BCDC battery connection.

We wired the vehicle Anderson plug input from the drawbar to the BCDC with the correct size battery cable and a new Genuine 50a Grey Anderson plug with boot and cap.

Coming back to that 160W roof solar panel connected to the solar input on the BCDC...we removed the solar from the BCDC, so now it acts purely as a 25A DC Charger.

Instead, we linked a Victron 15A Smart MPPT Solar Controller to the roof panel, which means John’s roof solar will work in addition to his BCDC, receiving 25A from the BCDC and an additional 10A or so, from the solar panel. That's up to 35A whilst travelling. Bonus!

Out came the damaged 240V charger and in went a new Victron Smart IP22 20A 240V Battery Charger. The Victron IP22 range of 240V chargers are designed for permanent installation and have a built-in fan to keep the charger cooler, for more efficient charging.   Another great feature is Bluetooth, which allows for Victron synchronized charging. This means that the charger talks to the Smart Shunt for accurate battery readings, and the solar controller, so the system knows exactly what is happening whilst charging. We are also able to fully customise the charging parameters specific to the battery,  achieving optimum charging and battery health.

We removed the hotwire feed from the caravan power supply so it stopped trying to charge the lithium battery, but will still charge the Breakways' battery.


The faulty Vibration Sense Relay switch was removed from the fridge wiring and the fridge was wired to switch on and off with the vehicle ignition. 

For convenience, we installed an Anderson plug mounted to the drawbar of the van, so John can plug his vehicle fridge to the caravan and run it from the van's lithium battery when parked up. 

And after all that rewiring and neatening up, we programmed all Victron products to work seamlessly together, achieving optimal charging and accurate battery monitoring.  


Not quite finished, we turned our attention to John's vehicle, installing an actual fridge wiring circuit to the 12 pin socket, which is switched by the ignition key.

Now John can now power his caravan fridge while he is driving. Happy days!

In this instance, the three way fridge uses only 14 to 15A, so running fridge power via a 12 pin socket is appropriate. If the fridge was a newer Auto Switching Fridge, it would use 24A, so a power feed would be connected via an Anderson plug and not a 12 pin socket.


We also removed the vehicles' reverse wire from the trailer socket and installed a new 12V hotwire feed to charge the Breakaway battery in the caravan. 

We'd say John's probably a bit less frustrated and enjoying his travels a whole lot more.

Having off-grid battery system problems and can't relax on your getaway? Contact us.



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