Installing 12V Supply Socket for Camper Trailer

[Tesa04]

Hi,

I’m a newbie to this forum and to PHEV motoring. I am awaiting delivery of an Eclipse Cross PHEV in Sydney that I am assured is the same as 2020 model Outlander except for the body shape.

I will be using the vehicle to tow our 750kg camper trailer that is fitted with a 100AH lithium ion deep cycle battery. The camper is also fitted with a Projecta IDC25L DC/Solar battery charger and a Projecta IC2500L 240v battery charger. The IDC25L is setup to accept a 12v supply from the tow vehicle.

I am have difficulty finding definitive advice and information on how to wire the 12v supply plug in the PHEV. I am wondering if someone could share their experience of wiring an Outlander/Eclipse Cross to supply a deep cycle battery in a camper trailer/caravan?

I understand the ICE does not have an alternator and that the 12v starter/accessory battery is charged from the traction battery via a DC to DC charger. One of my concerns is that the IDC25L will draw up to 25A and I wonder if this might exceed the capacity of the vehicle’s DC to DC charger? The IDC25L requires a wire to be connected to the vehicle’s ignition circuit if the vehicle has a smart alternator. In a phone call to Projecta I was told that the ignition wire must be connected in the case of the Mitsubishi PHEV’s.

Any advice will be gratefully received.

 

[disconnect04]

Hi Tesa04,

There are a few good threads on here about trailer wiring connections. This thread covers the location of the connector for the OEM trailer plug and has some photos. This shows how it all goes together. I think that wiring is all protected by a 20A fuse though, so you probably can't connect your charger to the trailer wiring that is supplied through the tow hitch connector.

The ignition wire in your DC-DC charger is used to switch the charger on and off in situations where the charger is connected straight to the car battery and so will still have power when the car is off. This prevents the charger draining the car battery. Something to bear in mind is that the PHEV's auxiliary battery is fairly small and expensive to replace and I'd advise against putting any loads on it because if it dies the car won't turn on. Another issue is that when the car is started in accessory mode (without the foot on the pedal) the low voltage power supply is not connected and loads are supplied by the auxiliary battery. It is possible that your charger could end up supplied by the vehicle battery and that is not good.

One way to set it up would be to install a voltage sensing relay at the charger end and wire the relay output to the ignition terminal of the battery charger so that it only switches on when the car's low voltage power supply raises the voltage. Something cheap like this this would work. In any case you will need to have an additional cable from the car to the trailer cable to accommodate the additional current, or you could use a lower current DC-DC charger like the REDARC BCDC 1206 connected to the provided trailer wiring.

Good luck.

 

[littlescrote]

^^ Good advice but it might be more helpful for future readers to use the correct terms of auxiliary battery for the 12V battery and drive or traction battery for the big one.

 

[jaapv]

Why not plug a regular charger into the 240V (maybe 110V in your area) socket of the PHEV?

 

[Tesa04]

Hi Tesa04,

There are a few good threads on here about trailer wiring connections. This thread covers the location of the connector for the OEM trailer plug and has some photos. This shows how it all goes together. I think that wiring is all protected by a 20A fuse though, so you probably can't connect your charger to the trailer wiring that is supplied through the tow hitch connector.

The ignition wire in your DC-DC charger is used to switch the charger on and off in situations where the charger is connected straight to the car battery and so will still have power when the car is off. This prevents the charger draining the car battery. Something to bear in mind is that the PHEV's auxiliary battery is fairly small and expensive to replace and I'd advise against putting any loads on it because if it dies the car won't turn on. Another issue is that when the car is started in accessory mode (without the foot on the pedal) the low voltage power supply is not connected and loads are supplied by the auxiliary battery. It is possible that your charger could end up supplied by the vehicle battery and that is not good.

One way to set it up would be to install a voltage sensing relay at the charger end and wire the relay output to the ignition terminal of the battery charger so that it only switches on when the car's low voltage power supply raises the voltage. Something cheap like this this would work. In any case you will need to have an additional cable from the car to the trailer cable to accommodate the additional current, or you could use a lower current DC-DC charger like the REDARC BCDC 1206 connected to the provided trailer wiring.

Hi Disconnect04,

Thank you for your reply. I aplogise for my slow response. My post had not appeared after a couple of days and I thought it had been rejected because of the reference to the Eclipse Cross rather than an Outlander.

I don't know what is in the standard Mitsubishi tow bar wiring kit in Australia but it will be nothing like the UK kit your reply referenced. Australia uses a flat 7 pin trailer plug that covers, tail lights, stop light, traffic indicators, electric brakes, reversing light and earth return (https://www.narva.com.au/resources/trailer-plug-wiring-diagram). In particular, standard wiring does not provide any power supply circuit to the trailer. In my case, the power supply to the camper charger will be independent from the tow bar wiring installation.

In the case of the Projecta DC to DC charger, the ignition wire is designed to cover installations in conventional ICE vehicles that have smart alternators that are subject to control by the engine control unit. For vehicles with a traditional alternator, the ignition wire connection is left open. This is the case on my 2012 Subaru. The IDC25L is designed to turn on when it senses a 13.4-20V supply and turn off at <12.8V. This ensures that the tow vehicles starter battery is not drained when the alternator is not running and obviates the need for a voltage sensing relay. My experience with the Subaru demonstrates that the set up works.

Currently, neither the Eclipse Cross nor (I think the Outlander) PHEV's being sold in Australia include the 1500W AC output socket in the rear of the vehicle. The Eclipse Cross will include this feature later this year and I assume it will be in the all new Outlander model. If my vehicle had this feature i'd be in the clear and set up a supply to the 240V AC charger in the camper.

Through the Mitsubishi dealer I am chasing advice on the specifications for the DC to DC inverter in the vehicle that supplies the 12V circuits and chargers the auxiliary battery. Given the heated seats and other services I presume the inverter has a rating of 600W or more. If this is the case, it has the capacity to supply the trailer during highway cruising in Australia. However, the other question is, is the DC to DC inverter supplying all the time or is it intermittent in some way? I read somewhere that it supplies at 14.2V. On first glance, it would seem the Projecta IDC25L would be compatible with the vehicle ie switches on when it sees 14.2V and switches off when the voltage drops below 12.8V. The unanswered question is how many watts can it supply.

Cheers

 

[Tesa04]

Why not plug a regular charger into the 240V (maybe 110V in your area) socket of the PHEV?

Totally agree with your suggestion IF the Australian spec for the Eclipse Cross included the 240V socket! Alas, the 240V socket is only due to arrive in vehicles delivered much later this year.

Cheers

 

[disconnect04]

Hi Tesa04,

Based on my observations driving around with a $2 digital voltmeter plugged in to the cigarette lighter socket, the voltage never drops below 13.6, and nor should it, that is the float voltage the auxiliary battery calls for.

Since you obviously have the means to do it, why don't you go hook up your multimeter, turn on the beams, seat heaters, stereo, and any other 12v accessories you can think of, read the voltage and report back.

Cheers

 

[disconnect04]

Further to this, assuming you have it wired to the auxiliary battery and you are going to rely on the voltage sensing relay inside the charger to protect the auxiliary battery, the system will cut off supply to the auxiliary battery if there is a flow of more than approximately 70 amps toward the auxiliary battery, see https://www.myoutlanderphev.com/forum/viewtopic.php?t=2136

Good luck

 

[Tesa04]

Further to this, assuming you have it wired to the auxiliary battery and you are going to rely on the voltage sensing relay inside the charger to protect the auxiliary battery, the system will cut off supply to the auxiliary battery if there is a flow of more than approximately 70 amps toward the auxiliary battery, see https://www.myoutlanderphev.com/forum/viewtopic.php?t=2136

Good luck

Hi Disconnect4,

Thanks for your responses.

We took delivery of the vehicle 2 days ago. Yesterday I verified 12.5v across the auxiliary battery when the vehicle is off or on ‘acc’. When on, there is 14.5v across the battery. Elsewhere on this forum I have read that the aux battery is 36AH. The battery in my vehicle is 56Ah. Interestingly, there are 175Amp fuses on the inward supply cable and outward supply cable at the aux battery which speaks to the 12v system having significant power capacity.

After talking to Projecta’s technical services desk and my preferred local auto electrician, I believe the trailer 12v supply system is very simple. Direct connection at the aux battery with a 40A fuse to a 50A Anderson plug on the rear of the vehicle. I will rely on the IDC25L charger in the camper trailer to cut-out if it senses a supply voltage less than 12.8v. The ignition wire from the Projecta DC to DC charger (required for smart alternators) will be left open.

When I get the opportunity, I will follow your suggestion of loading the 12v system by progressively switching on the vehicles 12v loads while measuring the voltage at the aux battery. I’ll report back the results.

The Mitsubishi dealership is tentatively scheduled to install the Mitsubishi tow bar next week and the 12v wiring is booked at the auto electrician the following week.

 

[Tesa04]

To Whomever Might Be Interested,

It is now is now 5 months on since my last post on this thread. I had the 12V supply for the camper trailer wired as previously described ie wired directly from the aux battery through a fuse to an Anderson plug. Over the last 4 months we have completed a 20,000km trip around Australia. The 12V supply to the trailer performed faultlessly. The DC to DC charger disconnected whenever the vehicle was 'off' which ensured the aux battery was not at threat of discharging.

On one occasion, while staying at remote National Park (ie no mains power) for several days, the camper battery was down to 75% charge. While out driving within the Park (without the camper trailer), 'Charge' was selected to save 10km of EV range in the traction battery. At the camp site, the car was switched on and camper plugged into the 12V supply. The charge in the camper battery rose by 10% (ie 10AH) in about an hour without a reduction in the EV range of the car. This 'experiment' validated the decision not to carry the weight of a set of solar panels for day time charging of the camper trailer battery.