Fridge Switching

[WildWG]

Previous owner of our 2000 2619 modified it so that shore power could be on while the TM is folded down. I would like to have the trailer loaded, folded down and hitched up the night before we leave for a trip. Trouble is, I have to leave it open so that I can switch the fridge from shore power to battery. It would be nice to be able to do this without opening the TM. Any ideas?

Bill W.

Switch it to battery before you close it down. As long as it is plugged into shore power the converter will power the refrig while keeping the batteries charged. Do it all the time. May be a good idea to run the frige fan also.

Ed

[Bill]

Digger's answer is exactly right. However, you want to watch out for the fact that many tow vehicles won't supply enough current down the charge line to run the refrig. The result is that while you are driving, the refrig draws some of its operating power from the TM battery, and when you arrive at your destination, the TM battery is dead.

There were a whole string of threads on the topic, and the fixes. This was one of the early ones.

http://www.trailmanorowners.com/foru...ead.php?t=7250

Bill

[WildWG]

Thanks to all for the info. I kinda feel stupid that all these years I have assumed that the switch on the fridge, when turned to DC, shut off all AC power.

The fellow we bought our 2619 from had fitted it with dual golf cart batteries. He also threw in a solar panel that I mounted on the roof and wired into the 12V system. We have never discharged the batteries, even boon docking for 10 days. WE do have a problem with keeping the fridge cold enough when on propane power and the sun is hitting the TM's street side.

Again, thanks for the tip.

WGW

[Padgett]

I need to run some tests but suspect a marginal charging system coupled with a high trailer load will drain batteries. My RV had problems particularly in rain (AC, wipers, all lights on) until I replaced a 100A alternator with a 140A.

When you turn the lights on in a TM, that is a minimum of twelve incandescent (why some replace with LEDs) each pulling about .6A or 7.2A (plus 4A for stop lights) just for the trailer. (1141 interior bulbs are about 2A each also)

Next the fridge heater pulls about 11 amps (150w at 14v) (nearly three times what a piezio or compressor based system pulls) plus another amp for the fan so now up to 19 amps. With other losses figure 20 amps.

This is why it is best to run the fridge for at least 24 hours before a trip on mains power so it should be cycling by the time you start.

If the TV alternator is already marginal (and cars today are designed to cruise at very low revs so alternator will be well below peak) then anything not provided by the TV will need to come from the coach battery. Those using new GC2s will have 105 amp hours before dropping below 10v. If the fridge is running constantly trying to pull down, that will give you about 13 hours of usable battery if there are no other loads.

Note: I used to carry a little 800w HF generator, running a couple of hours a day was enough to keep my 2-way (4 amp) fridge cold & a pair of GC2s charged. Nowadays I carry a 2500/2200w gen to be able to run the ac also.

Spacecraft designers have to consider energy budgets, why should campers be any different ?

[tentcamper]

The DC fridge only has about half the cooling capability of AC or propane. We're new to TM's, but always travel with our campers since the 80's running on propane. The two trip with the TM, we ran the fridge on propane starting the night before we left when we closed up the camper until we arrived at our CS.

On our return trip the last time out on our last leg of the trip. I decided to see how the DC would do. It was about 80 outside. The fridge temp rised about 2 degrees. But as Bill mentioned my battery voltage dropped to 12.27 during our 3 hour trip home.

[rickst29]

Originally Posted by tentcamper

The DC fridge only has about half the cooling capability of AC or propane.....But as Bill mentioned my battery voltage dropped to 12.27 during our 3 hour trip home.

All 3 "modes" of operation provide 140 Watts of heat (maximum). Propane flame output can fall off due to altitude, while AC and DC fall off according to the supplied voltage. If you can maintain high DC Voltage while the Fridge sucks all those amps (e.g., a Solar array like mine does this easily), then DC is at least equal to the other modes - and sometimes better, if they're compromised by altitude, low gas pressure, or AC brownouts.