So just a few questions about the 12v 3-way fridge operation and wiring.
1. While free camping I tried to use the 12v but nothing happened. I have since found out that its not possible to use on 12V only.
2. I noticed that I have thick black and white cables in my 7-pin plug. I would imagine it is for the fridge. So I would need to wire into the car 7 7-pin plug from the battery?
3. I also have an Andersen plug from the caravan, I wired in a plug-in on my car which charges the caravan batteries.
Am I missing something?
Thanks
Whenarewethere said
08:14 PM Nov 6, 2023
The 3 way fridge will draw 12 to 15 amps continuously, so your starter battery will not do its primary task after a few hours. Embarrassing stuff at best!
If you want to run a fridge off batteries, chuck out the 3 way & get a compressor fridge. Depending on its size of fridge you do need enough solar.
If you use a compressor Esky you are looking at 15 to 20AH per 24 hours.
landy said
09:27 PM Nov 6, 2023
The 12 volt element in your fridge is only to keep your fridge cold while travailing and should only be wired to run the fridge when your car engine is running. if you alter this you will quickly end up with a flat battery in your car.
Landy
Whenarewethere said
11:25 PM Nov 6, 2023
If you really want an actual 3 way fridge system which actually works instead of the rubbish still sold for decades.
You need to incorporate a compressor kit. Like the ones people use on boats where basically every fridge is built to the profile of hull shape (they often use 200mm of insulation for reducing solar requirements).
So effectively you have 2 (3 including 240v) fridge systems in one insulated box (as for people with no understanding of batteries & solar who still can only cope with whale oil candles!)
Looking at this from a long term running costs. How much are you spending on gas each fortnight & the stress of running out.
Maybe a compressor fridge in the long run has benifits which outweigh the negatives.
TimTim said
08:51 AM Nov 7, 2023
rodsfromday wrote:
Hi
So just a few questions about the 12v 3-way fridge operation and wiring.
1. While free camping I tried to use the 12v but nothing happened. I have since found out that its not possible to use on 12V only.
2. I noticed that I have thick black and white cables in my 7-pin plug. I would imagine it is for the fridge. So I would need to wire into the car 7 7-pin plug from the battery?
3. I also have an Andersen plug from the caravan, I wired in a plug-in on my car which charges the caravan batteries.
Am I missing something?
Thanks
1. Do not run your 3 way fridge on 12V when free camping because as pointed out it will drain your battery very quickly. Use gas.
2. Test the circuit on the black and white wires or trace them to the 12V fridge connection. If you wire to the battery so that the fridge runs whist you are driving then make sure you have an ignition controlled relay or again your battery will be drained very quickly when stopped and you are still connected.
3. It appears that that your fridge is not connected to your caravan batteries and rightly so. Mine is but my system set up is different to yours. The fridges 12V system is designed for keeping the fridge at temperature whilst driving not running off any of your batteries whist stopped.
Good luck
Tim
rodsfromday said
10:57 AM Nov 7, 2023
TimTim wrote:
rodsfromday wrote:
Hi
So just a few questions about the 12v 3-way fridge operation and wiring.
1. While free camping I tried to use the 12v but nothing happened. I have since found out that its not possible to use on 12V only.
2. I noticed that I have thick black and white cables in my 7-pin plug. I would imagine it is for the fridge. So I would need to wire into the car 7 7-pin plug from the battery?
3. I also have an Andersen plug from the caravan, I wired in a plug-in on my car which charges the caravan batteries.
Am I missing something?
Thanks
1. Do not run your 3 way fridge on 12V when free camping because as pointed out it will drain your battery very quickly. Use gas.
2. Test the circuit on the black and white wires or trace them to the 12V fridge connection. If you wire to the battery so that the fridge runs whist you are driving then make sure you have an ignition controlled relay or again your battery will be drained very quickly when stopped and you are still connected.
3. It appears that that your fridge is not connected to your caravan batteries and rightly so. Mine is but my system set up is different to yours. The fridges 12V system is designed for keeping the fridge at temperature whilst driving not running off any of your batteries whist stopped.
Good luck
Tim
Thank you Tim. I will look into your suggestions.
TimTim said
03:08 PM Nov 7, 2023
One thing I forgot to add is the day before you are leaving on a trip run your fridge off 240V for a few hours to cool it before packing it.
Just remember to disconnect it before you drive off
Tim
Whenarewethere said
04:45 PM Nov 7, 2023
You could also add a DC-DC converter next to the fridge. Due to the long run & the voltage drop due to wire resistance (I have then in my car, let alone a caravan).
A DC-DC converter you can set up to say 14.4 volts so the fridge will stay properly cold, instead of less than 12 volt due to the long wiring run.
rodsfromday said
06:14 PM Nov 7, 2023
TimTim wrote:
One thing I forgot to add is the day before you are leaving on a trip run your fridge off 240V for a few hours to cool it before packing it.
Just remember to disconnect it before you drive off
Tim
Thanks!
rodsfromday said
06:15 PM Nov 7, 2023
Whenarewethere wrote:
You could also add a DC-DC converter next to the fridge. Due to the long run & the voltage drop due to wire resistance (I have then in my car, let alone a caravan).
A DC-DC converter you can set up to say 14.4 volts so the fridge will stay properly cold, instead of less than 12 volt due to the long wiring run.
Thanks, will look into it
rodsfromday said
06:48 PM Nov 7, 2023
I opened my plug at my car and I have a trailer harness hooked up. So the pins where the fridge wiring would go have a white and black cable in. I might just pull the fridge wiring coming in at the van plug out, might have to lengthen it a bit and shove it into an Andersen plug. Contemplating on getting aux battery in and then run that to the fridge Andersen.
Am i on the right track?
rodsfromday said
07:05 PM Nov 7, 2023
But also......I have 2 batteries in the van. Now seeing that i only have a couple of 12V lights and a water pump running off it. I was wondering seeing that the batteries are being charged while I am driving, why could I not just hook the fridge, using an isolator switch, onto the van batteries? That way the batteries are being charged and supplying the fridge with power as well.
Whenarewethere said
07:59 PM Nov 7, 2023
You can wire the fridge to the caravan batteries. But still do it via a relay so when the engine is off the fridge stops.
What charging rate are the caravan batteries being charged at. You will now have another 12 amps on this circuit.
Put the DC-DC charger just before the caravan batteries.
When calculating wire resistance it is both + & - so from the engine bay you may have 12m but it is actually 24m calculating resistance.
Magnarc said
09:34 AM Nov 8, 2023
Hi Rod. Tim's advice is the way to go. We have had a three way Dometic fridge for ten years without a hiccup. I can see the benefits of a compressor fridge but the three way will never have any effect on your battery if you run it on gas whilst free camping, and let the car charge the battery when you are on the road.
Some may say that we have been lucky with our fridge but I can only speak as I find.
rodsfromday said
06:06 AM Nov 9, 2023
Magnarc wrote:
Hi Rod. Tim's advice is the way to go. We have had a three way Dometic fridge for ten years without a hiccup. I can see the benefits of a compressor fridge but the three way will never have any effect on your battery if you run it on gas whilst free camping, and let the car charge the battery when you are on the road.
Some may say that we have been lucky with our fridge but I can only speak as I find.
Hi Mag
Yes, i am quite happy with my 3-way as it works perfectly well. I was quite impressed by how well it worked on gas.
Thanks
Rodsvan said
04:36 AM Nov 10, 2023
I'd suggest using a temperature gauge (cheap ebay one either with a cord or cordless will do) to monitor the inside temperature of your 3-way fridge. The temperature inside the fridge will rise on a hot day unless you turn it up to a higher setting.
I usually have to turn it up to 7 on a hot day and then turn it down to about 3 overnight. If I forget to turn it down again overnight it will freeze everything.
Rod
Whenarewethere said
07:45 AM Nov 11, 2023
The thermostat may not be working if you can't set the temperature to within 2°C over a 24 hour cycle.
I don't have a 3 way fridge, but my feeling is that a 3 way has the performance of a peltier, about a 1/10 of a compressor fridge.
A compressor fridge at its coldest point of the evaporator plate on my baby 28L Waeco fridge gets down to -26°C.
But a compressor fridge is capable of 48°C below ambient temperature. So if 40°C it is still -8°C (probably your freezer is on average far lower, if you have reasonable thermal mass, from overnight refrigeration)
Again, if you have a DC-DC converter near the battery / fridge setup. The fridge will perform better. Great for those Pilbara situations.
(Chart is freezing 10.5 litres of water, Peltier vs compressor refrigeration)
Running on gas or 240v, Dometic 3 way Tropical (marked with T) will freeze contents if packed correctly, fridge has adequate ventilation and fridge side of van not parked in direct sun.
Don't run fridge continuously on highest setting, rather on second highest - it seems to work more efficiently.
Fortunately, my Evernew van has vented doors behind fridge rather than just vents, these open out like awnings top and bottom. We enjoy ice even in Qld summers.
rodsfromday said
08:41 AM Nov 13, 2023
Possum3 wrote:
Running on gas or 240v, Dometic 3 way Tropical (marked with T) will freeze contents if packed correctly, fridge has adequate ventilation and fridge side of van not parked in direct sun.
Don't run fridge continuously on highest setting, rather on second highest - it seems to work more efficiently.
Fortunately, my Evernew van has vented doors behind fridge rather than just vents, these open out like awnings top and bottom. We enjoy ice even in Qld summers.
Thank you, will keep that in mind.
rodsfromday said
10:37 AM Nov 13, 2023
So I was thinking. Coming off my battery I will have an isolation switch feeding the fridge. Will only turn it on when driving as I charge my batteries via my andy plug and run the fridge on 12V. That way I can only run the fridge, over short periods of time or when needed, from the 12V.
Hi
So just a few questions about the 12v 3-way fridge operation and wiring.
1. While free camping I tried to use the 12v but nothing happened. I have since found out that its not possible to use on 12V only.
2. I noticed that I have thick black and white cables in my 7-pin plug. I would imagine it is for the fridge. So I would need to wire into the car 7 7-pin plug from the battery?
3. I also have an Andersen plug from the caravan, I wired in a plug-in on my car which charges the caravan batteries.
Am I missing something?
Thanks
The 3 way fridge will draw 12 to 15 amps continuously, so your starter battery will not do its primary task after a few hours. Embarrassing stuff at best!
If you want to run a fridge off batteries, chuck out the 3 way & get a compressor fridge. Depending on its size of fridge you do need enough solar.
If you use a compressor Esky you are looking at 15 to 20AH per 24 hours.
if you alter this you will quickly end up with a flat battery in your car.
Landy
If you really want an actual 3 way fridge system which actually works instead of the rubbish still sold for decades.
You need to incorporate a compressor kit. Like the ones people use on boats where basically every fridge is built to the profile of hull shape (they often use 200mm of insulation for reducing solar requirements).
So effectively you have 2 (3 including 240v) fridge systems in one insulated box (as for people with no understanding of batteries & solar who still can only cope with whale oil candles!)
Looking at this from a long term running costs. How much are you spending on gas each fortnight & the stress of running out.
Maybe a compressor fridge in the long run has benifits which outweigh the negatives.
1. Do not run your 3 way fridge on 12V when free camping because as pointed out it will drain your battery very quickly. Use gas.
2. Test the circuit on the black and white wires or trace them to the 12V fridge connection. If you wire to the battery so that the fridge runs whist you are driving then make sure you have an ignition controlled relay or again your battery will be drained very quickly when stopped and you are still connected.
3. It appears that that your fridge is not connected to your caravan batteries and rightly so. Mine is but my system set up is different to yours. The fridges 12V system is designed for keeping the fridge at temperature whilst driving not running off any of your batteries whist stopped.
Good luck
Tim
Thank you Tim. I will look into your suggestions.
One thing I forgot to add is the day before you are leaving on a trip run your fridge off 240V for a few hours to cool it before packing it.
Just remember to disconnect it before you drive off
Tim
You could also add a DC-DC converter next to the fridge. Due to the long run & the voltage drop due to wire resistance (I have then in my car, let alone a caravan).
A DC-DC converter you can set up to say 14.4 volts so the fridge will stay properly cold, instead of less than 12 volt due to the long wiring run.
Thanks!
Thanks, will look into it
Am i on the right track?
You can wire the fridge to the caravan batteries. But still do it via a relay so when the engine is off the fridge stops.
What charging rate are the caravan batteries being charged at. You will now have another 12 amps on this circuit.
Put the DC-DC charger just before the caravan batteries.
When calculating wire resistance it is both + & - so from the engine bay you may have 12m but it is actually 24m calculating resistance.
Hi Rod. Tim's advice is the way to go. We have had a three way Dometic fridge for ten years without a hiccup. I can see the benefits of a compressor fridge but the three way will never have any effect on your battery if you run it on gas whilst free camping, and let the car charge the battery when you are on the road.
Some may say that we have been lucky with our fridge but I can only speak as I find.
Hi Mag
Yes, i am quite happy with my 3-way as it works perfectly well. I was quite impressed by how well it worked on gas.
Thanks
The thermostat may not be working if you can't set the temperature to within 2°C over a 24 hour cycle.
I don't have a 3 way fridge, but my feeling is that a 3 way has the performance of a peltier, about a 1/10 of a compressor fridge.
A compressor fridge at its coldest point of the evaporator plate on my baby 28L Waeco fridge gets down to -26°C.
But a compressor fridge is capable of 48°C below ambient temperature. So if 40°C it is still -8°C (probably your freezer is on average far lower, if you have reasonable thermal mass, from overnight refrigeration)
Again, if you have a DC-DC converter near the battery / fridge setup. The fridge will perform better. Great for those Pilbara situations.
(Chart is freezing 10.5 litres of water, Peltier vs compressor refrigeration)
Don't run fridge continuously on highest setting, rather on second highest - it seems to work more efficiently.
Fortunately, my Evernew van has vented doors behind fridge rather than just vents, these open out like awnings top and bottom. We enjoy ice even in Qld summers.
Thank you, will keep that in mind.