Portable Fridge 3 way

Tuco,
Thanks for the reply, just tossing around alternatives. I noticed that some compressor types like Reefer use an inbuilt inverter as they believe a 240 volt compressor is more effecient than a 12 volt compressor. If my 3 way (I know it's not a compressor type) is properly secured by tie down straps & behind a cargo barrier and the inverter is correctly wired by a qualified electrician I really can't see why this would be any more dangerous than any other 240 volt appliance that is in my home. My fridge on 240 _Affordable_Storage_Drawers.aspx 90watts, so according to JayCar I only need a small inverter ( they could be telling porkies) to power the fridge. So I'm still confused as why this would be a very inefficient way. Is it that on 240 the fridge has to be dead level but on 12volt there is more tolerance to the travel of a car. I'll appreciate any feedback.

Cheers,
Mark

Tuco,
This question is off the point of this thread but...
I found one of your threads in the archives regarding using Dick Smith wire W 2017 for a 12 v lead for the Chescold fridge. Can I use this wire from the battery to the rear of the car as well?

Thanks
Jack

Hi Jack - yes you could use the W2017, however for a long run like from battery to rear bumper you would be better using something heavier. W 2017 is shown in the DSE catalogue as having a cross sectional area of 3.5 mm2. Most people advocate having at least 6mm2 with long DC runs to the rear bumper. I'm using W2306 (18.8 mm2) in a single run only. I use the vehicle chassis/body for the earth return. Both my caravan and camper trailer are wired with W2302 (7.1 mm2) and I use 50 Amp Anderson plugs for the connections. I do not use the heavy large 7 pin round trailer plug for the DC supply at all.

W2017 is essentially 'monster' OFC speaker cable - but is very effective for carrying DC and the multi strands make it very flexible and easy to use in the likes of a Chescold DC cable - where it may need to be coiled up and stored.
When I had a Chescold 70 Litre fridge freezer - I did away with the pathetic DC connector on the rear of the fridge, and wired W2017 directly to the !2V heater coil. The increase in voltage at the coil - AND fridge performance was amazing.

Tuco,
Thanks for the reply. I have read just about everything said on ExplorOz regarding Chescold and have followed the suggestions exactly. I had already followed your suggestions and had wired in the W 2017 directly to the DC coil. Next I have to do is wire the car. I have looked at the heat exchange design and I am looking at wrapping alfoil around the coils and upper pipes of the heat exchanger, making sure the wires from the two coils are not affected. Then wrap the insulation around that. I am looking to trap more heat in for longer. Can you see a problem with this idea? I heated the alfoil over a gas stove and it didn't melt, so I figure the heat exchanger would not have enough heat to cause a problem.

Thanks again
Jack

Hi Jack - before you go ahead and do the alfoil wrap, check the performance that you are getting with just the wiring change.

If you do more than one change at a time, you may never know which change was effective or not. I'm not saying that the foil wont work, just that it is better to change only one thing at a time before retesting.

We only use an absorbtion fridge in the caravan ( Dometic 2 way gas/240V) - but use an Evakool ED70 12V in our 4x4. It works much better than the Chescold, and we keep it powered with Kyocera 120 W solar panel.

cheers - Tuco

Hi Jim,

Thanks for reply, I also have a Terracan and for a while I thought I was the only one. It's good to find other Terracan owners, I hope you are having as much fun with yours as I am with mine.
Bak to the fridge question, my 3 way only _Affordable_Storage_Drawers.aspx 90watts on 240 so a small inverter should do. I replied back to Tuco as he was adamant that this way was pretty inefficient. Just looking at alternatives as I have the inverter and was goiny to install it in the cargo area anyway.

Cheers,
Mark

Mark,

My Jerry Can is a gem. I love it.

Sure the inverter may be inefficient, but whilst you're driving and your alternator will produce more power than you can use, who cares? Then when you stop you switch to gas. If you've already got an inverter, give it a go, why bugger around with special 12 volt wiring?

Cheers,

Jim.

Jim,
Thanks mate, my thoughts exactly, I'll give it a go and let you know how it works.

Cheers,
Mark

Hi Brett,

According to the manual my fridge _Affordable_Storage_Drawers.aspx 90watts on 240 & 75watts on 12volt. I can appreciate if I get the 12volt wiring right with no voltage drop the fridge will work OK on 12 volt, just seeing if their is an alternative to upgrading the wiring as I have the inverter.

Thanks for the input,
Cheers,
Mark

Brett,
This bit about being dead level does not accord with either my experience or with the handbook for a Dometic fridge that I had in my old caravan. The book says that these fridges work OK on 12v whilst a boat or vehicle is moving because the liquid ammonia/hydrogen phase sloshes around and prevents significant cycling of the vapour phase into the condenser area.
My experience is that it is very often difficult to find a 'van site that is level in both directions, but the fridge still worked when a few degrees off level. In fact I deliberately tried the off-level setting at home during a dispute with a frdge repairer and got good performance when a fair bit off level.
Do agree though that 240 volts be treated with great respect. Depending on the body's resistance (and it will be lowered by getting wet at the campsite) a 240 shock can be fatal. On the other hand the safe limits for DC, even in wet conditions, are 32 volts RMS (root mean square) and 45 volts peak, which makes 12 volts very comfortable to live with.
Des

A 150 watt invertor can put a lot of dirt on top of you Jim, don't mess with it. It only takes milliamps at 240 volts to kill you. I have a bad habit of testing the charge in 9 volt batteries with my tongue, apparently a few with weak hearts have been knocked flat doing this.

Have a read of this Jim, interesting stuff.

http://www.bassengineering.com/E_Effect.htm

Thanks Ray

Mark,

I often let the kids use the laptop, via an invereter to watch DVD's. I wire it safely, with fuses and I cant think it is ant more dangerous than using a TV at home.

Why is 240 more dangerous in a car than in a bedroom I ask.

Cheers,

Jim.

Probably only more dangerous if it's a Heath Robinson installation with no concern for safety.

A danger is that the inverter will often be sitting on the floor which is the first thing that gets wet if you happen to stall during a river crossing and get water in the car. The fuses may blow before damage is done but there isn't the equivalent of an Earth Leakage Detector or Residual Current Device that would protect you in you bedroom (assuming recent house wiring). Also, the design of the inverter will impact the level of danger - if the 12v ground isn't isolated from the 240 ground/neutral (as in some cheap inverters) then there is higher risk of the chassis being one half of a 240v circuit.

Adrian