Lithium batteries

Hi Allen,
The van Has two 100 a g m batteries on board already, but appears that when you are stopped or even towing the van 's fridge doesn't appear to draw power from them. At the moment the fridge is drawing power from my main cranking battery, so if you are stopped for any period of time and you don't turn the fridge to gas, and disconnect the power from the vehicle to the van I wind up with a flat battery, and to me this is unacceptable. My solution is to put a second battery into the vehicle to run the fridge while parked and travelling and isolate the main cranking battery when I turn off the ignition leaving the second battery to run the van fridge, if that is feasable

Hi Bruce,

Does your van have a selector switch to select the power source, i.e. Van, Car or Both? IMHO, best position is both.

I am not an Auto Elec., but I would have thought that two 100 Amp AGM batteries should keep a 3 way fridge going for at least a couple of hours. There is definitely something very wrong with your set up, it sounds like your "house" batteries are not being charged, or are completely "stuffed". I am surprised that an Auto Elec. could not find the fault.

Macca.

Hi Macca,
I am no auto electrician either that is why I leave those things to the experts. The house batteries are fine they are brand new as I let the original batteries run flat over a very long period, I forgot to plug the van in after a trip once and we never moved the van for six months or more, so new batteries were required
the van has a smart switching system for power to the fridge, it draws power from the most strongest source, and while you are driving it comes from the car when you stop and turn the gas on for your morning cuppa and ya gotta have a cuppa at ten o'clock smoke oh when your on the road it switches to gas, as the the power from the car used to turn off as soon as the motor stopped and the gas would automatically kick in, does that make sense

.
Ah, so it is a 3-way absorption fridge, which will draw a continuous 15 Amps when connected to 12 volts.
And you do have AGM batteries in the van, 200 Ah in fact.

Well the sums show that such a fridge will draw 15Ah from any battery for every hour that it is in use so the battery needs to be sized for that. i.e. a 100Ah AGM will provide 3 hours at best.

For starters, any load in the van, be it fridge or other, should not be drawing power from your car battery when the motor is off. If it is, or can, then you have a fault..... either the automatic isolator is faulty or you don't even have one. Even if you were to put a "second battery in the vehicle" it would still need a functioning isolator to protect the cranking battery from being discharged. This is not the right way to correct the problem you have.

The correct setup is to have the fridge in the van being able to derive 12v power from the car's alternator whilst driving but to disconnect when the vehicle is stationary. At that time (stationary) it is an option for the fridge to transfer to the van batteries if they are sized to accomodate the 15A load for a limited period. Otherwise it must be switched to gas or be out of operation. If it is connected to the van battery, or any other for that matter, it is imperative that a low-volt cutout protection be fitted to ensure that the fridge cannot draw down the battery to below a safe preset voltage or batter damage will occur.

Putting another auxiliary battery (lithium or otherwise) into the vehicle to supply the fridge seems to be rather pointless to me when you already have 200Ah of AGM in the van. Why not use them?

It seems that your whole auxiliary wiring system needs sorting out. The cabling size is in question, there appears to be a problem with isolation, and the connection of the fridge is in question. Whacking in another battery will not solve your problem.
Sorry to be blunt, but certainly do not waste money by just putting in a lithium as a band-aid solution.

You wanted advice, well here it is....you really need to get the whole thing looked at and rectified by a competent auto electrician. And by that I mean one that has established competence in 4WD auxiliary systems. But still feel free to ask any further questions.

Thank you all I.
think I shall get a sparkie in one that has been around vans and rangers to have a look at the whole system, before I go jumping in the deep end where I cant swim.
thank you gentle men for you in put it has been gratefully appreciated, and given me a new direction to try .
thank you very much

.
That really is a good approach Bruce.
But by all means return here if you receive proposals that you wish comment on.
There is a lot of experience here especially in the black arts of lithium and solar.

I agree with Allan & has stated you need a good sparky & get him to check how your 12 pin trailer plug is wired as i will bet its also wired wrong
good luck

BroodieH3,

From reading all that you have posted, it seems to me you used to have a working system with your Pathfinder where when driving the 3 way fridge would run on 12V and when parked it would automatically switch to gas, then auto back to 12V when you got moving again.

I don't know your budget, but if the above is correct, and given that you have 200Ah battery capacity in the van, I would find a competent auto sparky and tell him/her that you want:

1 the 12V supply to the fridge to be from the van battery. Nice big cable to reduce voltage drop, say 8 AWG.

2 if you don't already have it, install a decent dc to dc charger in the van, near the van battery.

3 Your sparky may not be able to do this, but your Ford dealer can - have your Ranger's so-called "smart charge" turned off. Not 100% necessary if you use a decent dc to dc charger in the van, but IMO the smart charge system is there to maybe save you 10 millilitres fuel per 100km. Turn it off to do your crank battery a favour at least!

4 Have your sparky make sure the cabling supplying 12V to the van (ie from the crank battery all the way to the dc to dc charger in the van) is fat. At lease 8 AWG, preferably 6. Purists might say 6 is not big enough, but it is a practical compromise. And that's AWG wire size, NOT mm as in auto cable.

5 If you do the above this next is not compulsory, but ... I don't like having a permanently live supply at the towbar, be it a 7 or 12 pin socket or a separate Anderson. I recommend installing an isolator in your tow vehicle so that when the engine is off, so is the 12V supply to the towbar. Your sparky can do that.

This is the way my rig is set up. It has worked flawlessly for 12 years.

.
RMD, It had not occurred to me that it may have been a 3-way fridge. And if it is then my "160Ah of battery" and "160W solar" may be a bit light on.
Even if a better proposition, were I to suggest a change to a compressor fridge to conserve energy, it may be a "bridge too far" for Broodie's budget.

If a compressor fridge, then even in hot weather and running all the time it shouldn't flatten starter battery during just a quick look around. A lithium will hang on for longer of course but it too will sink if heavily loaded. One must remember when charging process is restored it still takes time to achieve . Having sufficient solar but not quite enough goes part way and slows the rate of battery discharge or lengthens time off full supply. All a balance and juggle act.

Hi RMD>
The fridge is a three way fridge and normally when free camping we run the fridge on gas. The original tow vehicle for this van was a Nissan Pathfinder, and the electronics were set up when we pick the van up in Victoria and they set the vehicle up to the van and we have never had a flat battery until this trip and the change of vehicle from Nissan to the ford Ranger.
One of the sparkies that had a look at the system, told me the wiring that was in the Rangers towing harness was to lite to do what we wanted it to do but offered no solution to fix the problem, so we carried on with what we had, and the bloke in Queensland gave us half a solution, but created another problem. that is why we are looking at a second battery and Isolator switch so no more flat batteries while temporarily parked

RMD, great to read that! That is awesome work.

So to reiterate, you are able to run a three-way-fridge on two battery plus solar systems, with a cut-off at low voltage?

What specs do batteries, solar panel and regulator have and how long can the fridge run?

Thank you!

HKB,
I think you have hit the nail on the head, while travelling the fridge used to turn itself straight to battery power when ever the vehicle was started, even when we first changed vehicles, then we hit those really hot days over Christmas and that is when we lost power to the fridge. The flat battery only started after Queensland sparkie, gave us power back on the fridge from the battery when started.
So what would your recommendation be if not the second battery please.

QLD.
Broodie is wanting the fridge to run during the daytime stops and not flatten the battery. Therefore, with sufficient solar it isn't really running off a battery, be it lithium or AGM. Enough solar and reg will do it for him most times during the day. Setup properly it will completely run the fridge or ata minimum, lengthen the duration until he is on the road again and charging. Either way, no flat vehicle battery and maybe a slowly discharging aux. Just telling someone to buy a compressor fridge may not solve the problem financially.

Why not just use a good old fassioned ignition fed relay?

Yes an ignition fed relay will work too.

I'd agree. Fit a fridge switch in the van so the vehicle battery is protected. Turn on the gas bottle when stopped so the fridge stays cool (presuming it automatically selects gas when 12v is not available*). Turn off the gas when you drive away again. Pretty cheap and effective solution.
*If the fridge doesn't automatically switch to gas when 12V is not available, you'll have to start the fridge manually.
You can improve an absorption fridge's performance quite dramatically with Karl's Kool Fans.

Everyone else calls it NORMAL charging. If turned off it doesn't affect the vehicle.

Hi Bobjl,
We have been turning the fridge to gas and also disconnecting the power source from the vehicle to the van when we stop and go shopping . we don't have a problem when we are camped for an extended period like a week or so, as the fridge is either on 240 or gas.
from what I have been able to learn from the previous responders is the vehicle is not electrically modified for the van, as we never had a problem when we were towing with the pathfinder, so I shall get the Ranger 's electrics modified for the van. Bob from what you have said it sounds like I have been travelling , with the van the same way you do only I have to manually disconnect my vehicle power supply to the van, where as you don't have that problem.
thank you very much for your input as you have confirmed my choice of rectifying the problem.
I need a sparkie that knows what he is doing.

Thanks that makes good sense Pinko. Whilst most will correctly interpret your example re fridge start up on gas, obviously we do not want pilot lights aflame at a servo. I was [casually] involved in a serious explosion causing horrific burn injuries at a Servo in NSW long ago which arose directly from a pilot light flame in a camper van. Similar to many others, my gas remains off whilst in transit and is only turned on when away from potential combustible products.

Hi Pinko.
our fridge works exactly the same as yours, without a doubt. We have to turn the gas on and off while travelling, if we are going to be stopped in a town for an extended period ie: shopping and sightseeing we have to disconnect the power from the vehicle and turn the gas on, other wise we wind up with a flat battery if we are away from the vehicle for more than an hour.
so my solution is to get the ranger re wired to tow the van and then it should be happy days again

Hi Broodie
At the moment if you pull the trailer plug/anderson connector when you stop to go shopping etc. the fridge PC module will sense this and use the caravan house battery power to activate the fridge piezo and ignite the fridge (after 15 minutes).
Or like you said add something like this which is activated from the vehicle ignition.