Car or van lithium upgrade

It should work. A few thoughts.

1/ Ensure the Vans AD/DC charger is turned off when the car is connected up, no point going through all the conversion losses to charge the van battery from the car ones, and it might overload the inverter.
2/ Once at 240v the voltage losses are less of an issue, so running an extension cord from the car to van should be fine.
3/ You'll need a 15 to 10amp RCD, as the van most likely have a 15amp plug.
4/ Depending on your AC, even 400 AH is only going to run it for a number of hours.

It is a lot of extra weight in the car, so check your GVM, might mean moving some other things to the van.

Darro

We have 400ah of Lifepo4 (2x200) in our caravan and would have liked a bit more. As best practice is to not parallel batteries of a different spec or age, so adding another battery/s was not an option.

We upgraded the vehicle to 400ah Lifepo4 (2 x 200) and use the vehicle 2000w inverter to "decant" across to the caravan as needed. * Plugging into the caravan inlet and the caravan 240v charger then tops up the caravan batteries as required. No different to when at home or in a caravan park or any other external 24v source.

* I do use an amphibian device from the inverter 10amp GPO to the caravan 15amp plug extension lead.

** In our case our caravan 240v inverter charger has a user programable ability to reduce the incoming amps so as to not overload the inverter. I limit the input to ~7amps for our 2000w inverter. I also put the caravan charger on "charger only", mode during that process, we still get 240v through the caravan, but I wouldn't use the air con simultaneously unless you have a decent inverter/charger in the caravan such as Victron Multiplus or similar.

Workes a treat for us.

Overloading the inverter would depend upon the current draw of your 240v charger in the caravan.

2000w inverter/ 240v = 8.3amps. Allow ~80% efficiency of your inverter then theoretically it would potentially overload at anything greater than ~ 6.6 amp (~1600w) continuous

If your caravan batteries are depleted and the caravan charger starts to draw from the inverter and pump it in, then it's possible that your inverter may overload.

If you have been using your Honda 2.2 generator and it doesn't struggle when you charger in the caravan is charging the batteries, then it's likely you caravan charger is ok to use from the inverter as the Honda rates ~7.8 amps.

In our case our inverter charger in the caravan can draw significantly more when charging the batteries. So, on mains I have the current limit at 15, and when using the generator or decanting from the vehicle I change input current to 7amp limiting

Use your existing experience of your Honda generator as to what the caravan charger may be using.

It also depends upon how your caravan is set up. When on 240 mains power does it charge the batteries simultaneously or do you manually switch that option on/off

I was considering one of these 12v a/c units when we get a van with a descent amount of batteries to support it. Just have to see if someone sells them in Australia when were ready.
https://outequippro.com/collections/top-mounted-air-conditioner
I'll be putting a 300ah lithium in the 4wd for the fridges etc and leave the van with it's own setup so it's charged off the car while driving also solar on the van roof with a generator I already have if needed. Just easier when you disconnect the vehicle for day or overnight trips and leave the van behind you know the fridge will be still cold and you don't have to hook the car up as soon as you get back and repack the fridge or if the wife wanted to stay with the van and wasn't interested in going into rougher terrain like mine. There's so many different scenarios it could also be good if you loose power at home the van has enough batteries so just run a power lead into the house for the fridge and the car isn't tied up then.

Hi Stefandsal,

Personally, I would not upgrade your van’s battery system if you intend to sell it in the next couple of years. You might be better to up grade the Auxiliary Battery system in the car if you occasionally camp without the van.

My Wagon has a 175 AmpHr PowerPaul Australia Cub LiFePo4 Battery coupled with a 2,000 Watt Renogy Inverter. There is a 60 Ltr. Engle fridge permanently in the back of the wagon that runs off 12 volt, although it is not switched on all the time, just when needed. The battery has a 250 AmpHr continuous discharge rating, and coupled with the inverter, it powers my 1,500 Watt Coffee Pod machine whilst the fridge is running. I carry a 200 Watt folding solar panel for when we are parked up to keep the battery charged up, particularly when we are without the van. The solar is a little short on capacity for the battery, and I would prefer a 300 Watt panel, but current finances do not permit me to upgrade the panel. So far I have managed to keep the battery “alive” without too much difficulty.

Do you camp without the van? If not, you probably do not need to do anything, but if you do (I sometimes travel solo without the van, so it made sense for me to have a better Auxiliary Battery system in the car), it would make sense to upgrade the system in the car. If you work out what your power consumption in the car would be, you could size the battery and inverter to suit, then size your solar capacity to suit the battery capacity.

Running a lead from an inverter in the car to power your van, whilst it sounds feasible, is not really practical. If you work out what the van’s consumption in Amps is, particularly if you are running 240 volt appliances such as kettles, toasters, microwave, fridge, (don’t even think about the Airconn), etc. it soon adds up. You have a generator to cover this scenario, more practical than trying to power your van from your car when parked up.

Of course these are just my opinions, and my system works for me, and how I/we travel.

Macca.