Help with understanding the 3 way fridge
- Thread starter AddItUp
- Start date
I always thought I might forget one day and flatten the battery. So I carry jumper leads, but will the deep cycle battery out of the van be enough to turn the car over?
Hi @AddItUp ,
No real dramas at all. I still have to finish up my write up so will post full details when I do.
As for the van, one road we went on between Kyogle and Killarney would have to be the worst bitumen in the country! I have seriously driven on better majorly corrugated dirt roads than that was! 85klm stretch and basically was in 3rd max for about 70klms of it! So if anything was going to shake or rattle it's way loose, this road would have done it!
BJ
No real dramas at all. I still have to finish up my write up so will post full details when I do.
As for the van, one road we went on between Kyogle and Killarney would have to be the worst bitumen in the country! I have seriously driven on better majorly corrugated dirt roads than that was! 85klm stretch and basically was in 3rd max for about 70klms of it! So if anything was going to shake or rattle it's way loose, this road would have done it!
BJ
Have a look on ebay for an alternator voltage booster, which is a diode which replaces the ALT-S fuse in Toyotas as they have regulated voltage output on the alternators. This drops the voltage output to limit emissions (load on the engine). The diode raises the output by around .5-.6V. I had one in my last Prado (which had dual batteries and ran fridge in Expanda) and now my LC200. Prado always ran at 13.8V with van plugged in running fridge. LC200 runs at 14.4-14.5V all the time as I haven't wired up to run Expanda yet. for the $30-$50 outlay, I don't think you can go wrong. As you are replacing a fuse, the diode will blow if you have a fault for piece of mind.
Hope this helps.
I think it tricks the ECU into not lowering the output by changing the voltage feedback to the ECU so it thinks it is lower than it actually is. My best guess anyway!
Hi @AddItUp . We've owned 6 Jaycos with 3-way fridges and have never had issues running them on 12V while driving apart from one time when I forgot to turn the fridge off while parked for a few hours. In that case, it didn't flatten the car battery because there was a bad connection on the 7-way plug/socket and the socket overheated, melted the plastic moulding, shorted against the earth pin and blew the in-line fuse in the car (never have understood why they have raw 12V +ve and -ve on adjacent pins!). That actually saved our bacon because a flat battery on an automatic tug is bad.
These days, I think all fridge leads are (should be) wired from the car battery via an isolating relay so that when you switch off the ignition, it automatically cuts the 12V to the van fridge. That's the way my last two cars have been wired.
If you have a 90l fridge, it can be fed using the 'reversing lights' pin on a 7-pin plug/socket because the maximum current drain is 10A (as long as you keep the pins free of corrosion so they don't get hot). However, if you have a 150l fridge, it drains 15A and Jayco fits a 12-pin plug which has 5 larger pins for higher currents. We towed a Discovery around Oz with this set-up and never had a problem.
With our new Prado using 6mm cable, I measure 11V at the fridge which, while it may maintain cooling for an already cold fridge, is too low for my liking. I plan to replace the 6mm wiring with 8AWG and buy the ALT-S diode/fuse mentioned previously for use when towing.
There's a lot of good advice elsewhere in this forum - and some dubious advice too. The only things I would say at this point are:
1. Make sure your car has an isolating relay.
2. Don't even consider running your fridge off the battery in your van.
3. Don't switch your fridge to gas when you park for a short while in case you forget to switch it back to 12V before you take off again - you may find yourself towing a ball of fire a few km down the road! The fridge will stay cool for a few hours without power.
Regards
DrD
Thanks very much @DroversDog for your detailed reply. Some great advice, much appreciated. Regarding your point 3 above...I'll certainly try and avoid towing a ball of fire down the road! 
@DroversDog Is the reason you would not run the fridge off the battery in your van because current draw will flatten it quickly.
What about for say a 7hr drive and then recharge of batteries at destination. I was sort of planning to do that. Then at destination I would use gas or 240V.
Cheers Geoff
What about for say a 7hr drive and then recharge of batteries at destination. I was sort of planning to do that. Then at destination I would use gas or 240V.
Cheers Geoff
@maccayak ,
That is what we did on our trip and as long as you can charge at the end of the day all is good. Without being able to charge, I think you would be eating in the dark pretty soon!
BJ
Hi Geoff. Yes, that is the reasoning. It will take a long time to recharge the battery if you leave it to run the 3-way fridge (at 10-15A) for any length of time.
When towing, use the car's alternator to run the fridge. Save the battery in the van for running the lights, TV, etc. when you are camped without 240V and use gas to run the fridge. In theory, you could charge the van battery from the car's alternator while towing while in turn running the fridge from the van battery but you would need a monstrous gauge cable to carry the sum of the battery charge current and the current to run the fridge.
The way my Discovery is wired (by Jayco) is via two separate 6mm cables from the 12-pin flat plug - one for the fridge (15A) and one to charge the van battery (presumably anything up to 30A initially if the battery is flat). These cables are totally isolated from each other within the van wiring and must remain isolated within the car wiring (via relay contacts) when the engine is not running to avoid the fridge draining the van battery via the car wiring loom (e.g. when parked and the van is still hitched).
Regards
DrD
We have a 17.56-2 with a 150 later fridge. The car has a 12 pin plug and has been set up with a relay so that if we have the fridge set to DC and we stop the engine, the battery stops supplying charge so we don't run it down.
If it's only a short stop then the fridge holds the temp ok. We pre-cool it on 240v at home before we leave so we can stock it for the trip. DC will hold a temp, but not cool it.
Any auto-electrician can sort it out.
If it's only a short stop then the fridge holds the temp ok. We pre-cool it on 240v at home before we leave so we can stock it for the trip. DC will hold a temp, but not cool it.
Any auto-electrician can sort it out.
On our trip around Oz, we drove all day on many days with the fridge on 12V and, even on hot days, frozen food stayed frozen and the rest of the fridge stayed cold. However, the auto electrician had wired the fridge and the battery charge leads using the same wires and I couldn't run the fridge and charge the battery at the same time (the 30A fuse would blow). So not all auto electricians know what they're doing.
@AddItUp, don't think I've said g'day so g'day and welcome! Some good advice here but don't stress too much to start with....one of my mates does a lot of K's with no 12 volt to his fridge and all good. One other thing which applies with all fridges is they keep temp better full rather than empty so make sure it's full of beer at all times!
Cheers.
Cheers.
G'day @Burnsy and thanks for the welcome. Yes, there has been some great advice. It's fantastic that the forum is so active and people are really keen to help out. Hopefully in time I can offer some useful insights also.
I'll let the missus know that I have been advised to keep the fridge adequately stocked with refreshing ale at all times.
I'll let the missus know that I have been advised to keep the fridge adequately stocked with refreshing ale at all times.
Hi @ AddItUp when we bought our van they told us if your not sure if the car can handle the fridge on the 12v don't stress, the fridge is like a big Esky just fill it up then put in a few frozen ice blocks (packed around the beer of course) should do fine until u can hook up to the 240v or gas when you set up ,that's what we do .I would like to know how some of the members here hook their vans up to the house and cool the fridge down over night before they leave as our 15amp plug won't fit our house power points as they are all 10amp . The fun of learning huh
Hi mate, there is a thread on powering van from your house but legally you have 2 choices. 1 have a 15amp outlet installed or 2 buy an ampfibian or simillar ( think that's how it's spelt) it allows you to safely plug into your 10amp circuit at home.Hi @ AddItUp when we bought our van they told us if your not sure if the car can handle the fridge on the 12v don't stress, the fridge is like a big Esky just fill it up then put in a few frozen ice blocks (packed around the beer of course) should do fine until u can hook up to the 240v or gas when you set up ,that's what we do .I would like to know how some of the members here hook their vans up to the house and cool the fridge down over night before they leave as our 15amp plug won't fit our house power points as they are all 10amp . The fun of learning huh