Truck Fridge and Westy fridge relay

[dieseltdi]

I have done some searching and reading and I haven't been able to come to a consensus among the various views so I wanted to toss this on the waters again and see what kind of storm I can stir up.

My Westy is an 82 so it doesn't have the fridge relay behind the driver's seat, it is mounted on the fridge and has a number of different connections for the various 12 volt functions of the fridge (fan vs actual cooling for instance). I know the purpose of the relay is to prevent running the old Dometic on 12V unless the engine is running to avoid running down the battery (82 only has 1 battery) and I just assumed I would include it while wiring up the new truck fridge. However, as I was reading the information on the fridge, it is quite clear that the control board will automatically shut off the fridge if the battery voltage falls below a certain level (11 volts I believe).

I know that I have started my TDI in the van at voltages below a full 12 volts but don't know exactly how far below the 12 volts. So my question does this give me enough of a safety margin without the stock relay? Eventually, I will have a house battery and solar but not in the budget right now.

[jimf909]

Here's my take...

If you're planning to run your TF off the starter battery you'll need to be paying attention and planning to turn the fridge off if the fridge will be running overnight w/out running the motor. Also, you're proposing a risky proposition so I'd strongly recommend carrying a Lion battery jumper with you. Your van probably won't start if you run the batt. down to 11v but it will with a jumper.

https://www.amazon.com/gp/aw/d/B0748D8KT6/ref=ppx_yo_mob_b_inactive_ship_o0_img?ie=UTF8&psc=1

A house battery will provide a healthy margin of error and only cost $150 or so. The solar gear starts multiplying costs.

How many days do you want to run the fridge on your starter battery?
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- Jim

[dieseltdi]

I guess for right now, I am talking about just camping overnight. I have looked at a small 35 ah sealed lead acid battery that would be pretty easy to fit under the drivers seat. I haven't taken anything out of the van yet as far as putting in the fridge. So I guess what I am looking to really find out is what is the easiest and simplest way to wire the thing up: with or without a relay.

[idahoskier]

The Truckfridge will likely run down a normal starting battery faster than you want. At 11.9v your 12v battery will be down to about 40% and at 11.0v that battery is not likely to start anything. You mentioned adding another battery, which IMO is the best solution. I like to have my fridge isolated from the starting battery so that I have one less chance to mess up. 35aH should run the fridge overnight depending on conditions. If its not enough for you then just add more aH or solar.

I would install a new charging relay (yandia or the like) to charge and isolate your house battery. A little more work than no relay but still a straight forward install.
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85 Westy w/ 2.2L Subaru
91 Westy w/ 2.5L Subaru - sold

[dieseltdi]

Well I guess the best bet will be a house battery. According to TruckFridge:

Average consumption: 40 amps/24hrs at 75° F ambient with an internal temperature of 36° F.

So a 35ah would be adequate for overnight but obviously bigger is always better in the cause of electrical consumption. Will need to measure the available space and find a local source for a Series 31 deep cycle battery which, I believe is the correct size or find some combination of smaller batteries. Not ready to jump into L-ion just yet. Thanks for the help. Hayden

[erdonline]

[dieseltdi]

By adequate, I mean overnight, say 8 hours. I have access to a 100 watt portable solar set up which could be used for longer camping but for overnight, I would think 35ah would be sufficient.

[erdonline]

Oh, I just read the thread a little more carefully. Remember that a lead-acid battery shouldn't be repeatedly drained down to less than 50% of its capacity, or its lifespan will be shortened.

I might sometimes come across as "anti-solar" in some of my posts on various forums, but I often see people looking to ad solar when they could get by with a good deep-cycle battery and charge it when they get home.

Have you considered a group 29 deep cycle? I got mine at WalMart, but some have stopped selling them. Many auto parts stores have them. Typical capacity is 105 to 115 amp-hours. They're large in physical size. I keep two of them under my back seat.

Ed
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'85 Vanagon Westfalia
'84 Vanagon 7-passenger
'98 Mexican air-cooled Beetle