Car fridge power draw.

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

MDS I am biased on the subject of batteries. Despite the temperature under the bonnet I go for AGM batteries but there are many who don't agree. First you need higher charge voltage and second they are heavy. Mine is 40kg. And heat kills them. But I have a 120 Ah AGM and have used them now for 7 years. 75 Ah in a wet cell is low without supplementing charging with wind, solar or routine engine running. I camp with a 100 W solar panel and it keeps up with demand. Previously I had to run the engine every day and go for drives.

Wiring may be an issue too but running in the garage is much easier than in the car. Best check voltage at the fridge in the car with fridge running and then check battery voltage. Should be as close as possible. In my 90 I had to replace the fridge wiring after a couple of years because while fitting more bits and pieces I accidentally crimped the wiring and lost more than half the conductors. Same sort of issue as you and so I had the fridge serviced. Same problem and lo the voltage at the battery was 1 V lower than the battery.

I think you can get better fridges IF you can get a refund. Checking wiring is a sensible idea and a larger battery or solar panel as funds allow. Bear in mind my 120 Ah AGM is a 13" battery cost nearly $400 and I had to build a custom battery tray.

Good luck.

What connectors does the fridge have? If you are using Anderson power poles I can lend you a monitor to get the full story on your fridge consumption though you can buy them for about $60.

Michael

[MDSimpson Advanced Member Find all posts View Profile Close MDSimpson]

Thanks Michael,
I'll look into a new battery, so something not a wet cell? One of the reasons I was so puzzled is, my multimeter readings are the same at the battery, at the socket for the fridge and also at my rear anderson plug. So would have thought this prove my wiring is ok. My fridge is connected to a cig socket, but recently I cut the standard fridge cable, and wired it directly to my fuse box in the rear. It is a 6 point powered fuse box with a 30amp circuit breaker.

Thanks again mate.



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[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

Did you check the voltage while the fridge was running? No load readings will be the same it is only under load that you will see a difference. Lots of info on here about batteries do some more research and don't just believe me! There was a site about caravans etc run by someone on the Gold Coast (?) that had some really good info on aux wiring and batteries. I will see if I can track it down tomorrow when I have a full screen to look at. Will post the links here if I do.

Edit: the losses could be through the connections. I run Anderson Power Poles and these are self wiping like the biggies and good for 45 A.

[MDSimpson Advanced Member Find all posts View Profile Close MDSimpson]

Michael, how do you terminate th fridge cable into an Anderson plug? The cable is quite small and the lugs are large?

I might grab the big cable terminators from work and look into it.


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[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

These little suckers not the full sized Anderson plug

http://andersonpower.com.au/store/in...roducts_id=407

And you can crimp and/or solder the cables easily.

The NL fridge has powerpoles as standard. I run twin 6 B&S from the aux battery to a power block such as this (one for black and one for red!)



and then from there to an amphenol connection with genuine 6mm2 (not 6mm automotive cable that is usually lucky to be 3mm2) paired cable (same as that supplied with the 40A powerpoles). I guess there will be people who are horrified at my use of the amphenol connection but they are rated to something like 100A and 100V. The amphenol connection is so I have it positively locked but next time I would just go with a powerpole connection as well because the amphenols are a pain to make up. Somewhere on the Anderson site is a bulkhead fitting.

Here is a pic of the monitor and the powerpoles into the NL fridge.



One website that talks about 12v stuff is this one

http://www.caravanandmotorhomebooks....cles/index.htm

Lots of good information though mainly tailored to caravanners. You used to be able to call the guy up and quiz him about his opinions and experience. Everyone will have their own views but I think do as much research as possible and make up your own mind knowing the pros and cons of the options.

[MDSimpson Advanced Member Find all posts View Profile Close MDSimpson]

What size wire is in the Anderson plugs you've shown? Does not look that big, so I should still be able to use the same wire, just better connectors. Hardwiring should be the perfect solution...

Ok, so I have decided to get a better battery. Looking for a Deka or Optima...
Any recommendations in places to buy and model numbers you can recommend???

I think it is just the wet cell, deep cycle 75 Ah, just does not cut it...


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[MDSimpson Advanced Member Find all posts View Profile Close MDSimpson]

Should be good down the South Pole.
The Roo.

Lol....


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[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

MDS the main from the aux battery to the connectors (which live in the jack compartment) is 6 B&S. The cable that runs from the socket to the fridge is 6mm2. There are complicated formulae which can tell what length of run of what diameter is needed to manage voltage drop. For the 5m (ish) run from the front to the back 6 B&S is good but 6mm2 is a bit small. For the 600mm or so that runs to the fridge from the socket 6mm2 is fine (and what was supplied with the fridge). I did the calcs yonks ago but no idea where they are now. Lost in one or two computers past I would guess.

Michael

[Gekko Lurker Find all posts View Profile Close Gekko]

"Here is a pic of the monitor and the powerpoles into the NL fridge."

mjrandom, what is that monitor you are using and where did you get it??

Gekko

[MDSimpson Advanced Member Find all posts View Profile Close MDSimpson]

MDS the main from the aux battery to the connectors (which live in the jack compartment) is 6 B&S. The cable that runs from the socket to the fridge is 6mm2. There are complicated formulae which can tell what length of run of what diameter is needed to manage voltage drop. For the 5m (ish) run from the front to the back 6 B&S is good but 6mm2 is a bit small. For the 600mm or so that runs to the fridge from the socket 6mm2 is fine (and what was supplied with the fridge). I did the calcs yonks ago but no idea where they are now. Lost in one or two computers past I would guess.

Michael

Sounds about right and what I have in car. The length if the smaller cable, from the powered fuse box to the socket is only about 100mm. But since I decided to hardwire, I just use the original fridge cable, terminated it and viola...



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[MDSimpson Advanced Member Find all posts View Profile Close MDSimpson]

"Here is a pic of the monitor and the powerpoles into the NL fridge."

mjrandom, what is that monitor you are using and where did you get it??

Gekko

Michael, I would be interested in this too...


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[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

I bought these. One for the fridge and the other for the solar panel. I cannot claim to have done the research as one of the engineers at work was looking to find something for his camper battery.

http://www.rc-electronics-usa.com/am...y-monitor.html

The solar panel is 4 wire and the fridge 3 wire as per below

http://www.rc-electronics-usa.com/am...onnection.html

I bought directly from rc-electronics. We bought 4 and the postage was about $20 from memory. HobbyKing and other similar places sometimes stock them (RC guys use them to work out flight times etc) so you may be able to grab one locally.

Also a few comments in here

http://www.pradopoint.com/showthread...007#post299007

I disconnect the solar panel monitor when I drive. Well I mean to, I left it once and discovered that when the engine is running and the alternator charging the auxiliary the solar panel doesn't put anything into the battery. I take this to mean that the alternator is punching out more volts than the solar panel which is regulated to 14V which is a bit odd so I don't think about it. Don't want the monitor under the bonnet when it gets hot anyway. I have left the fridge monitor on for months and no problems. The only reason it isn't on now is I didn't have an extra right angle amphenol fitting and so the cable sticks out and is vulnerable to damage from stuff chucked in the back. Have bought anothe so will set about doing that. Mind you when I get around to sorting out the auxiliary wiring and fitting the twin head compressor this winter I might just put some power poles in the back if I can cover up the mess left by the installer.

Oh and with the Anderson powerpoles you can buy plastic clips that positively joint them so there is no risk of the powerpoles coming apart.

Michael

[Whitey1 Advanced Member Find all posts View Profile Close Whitey1]

Our Evakool 40liter was drawing 4.5 A whenever the compressor was running this morning. Set on freeze. Just for a bit of a comparison for you.

[MDSimpson Advanced Member Find all posts View Profile Close MDSimpson]

Michael, that is brilliant info. You have helped me no end mate.
It'll cost me, but at least know what i am looking for now.

Now to chase down the monitor, do I can see EXACTLY what my electronics are doing...


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