3-way Fridge

Luckydog671

Luckydog671

Senior Member
Joined
Apr 29, 2014
Messages
817
Location
Tehachapi Mountains, Calif.
Hi all,

I know that the HiLo's are equipped with the 3-way fridges and I got to wondering if the alternator in my Tahoe was heavy duty enough to run it on 12V while traveling. I discovered that my alternator is a 145 amp model. Is this good enough to charge the little Dometic fridge?

Thanks,
 
Greg, you are running a very small amount of 12V juice through to the fridge. We have always recommended firing the machine on propane, but your truck will never miss a beat with this add-on.
 
The 12 volt mode draws about 15 amps. Your alternator should handle that without a problem. The only other thing to consider is that will the 12 volt charge line be heavy enough to carry the 15 amps. Many tow vehicles have wiring that tends to be on the light side and can't deliver the full intended voltage/amperage. What will happen is the TV will send what it can and the fridge will draw from the trailer battery for the rest. I can't say that is your case but just want you to be aware.
 
I think that I would go no less than 8 gauge, considering the length of wire needed and the amperage. Twenty feet of 8 gauge wire is good for up to about 35 amps. A 30 amp circuit breaker would be required somewhere near the TV battery.
 
"We have always recommended firing the machine on propane, . . ."

notalines -- LOL!!! (You're kidding, right!)

Dee
 
Dee Tillotson said:
"We have always recommended firing the machine on propane, . . ."

notalines -- LOL!!! (You're kidding, right!)

Dee
Click to expand...

Dee, there was a discussion of this a while back. The only real danger in using propane while driving is having it on while filling the gas tank in the tow vehicle. That danger is probably fairly small, since the flame is small and the trailer should be some distance away from the source of gasoline vapors. And, if you located everything so the trailer was upwind, I doubt there would be any danger at all. Still, I would not do it, and always use DC when traveling.

Rich, regarding the size of the wire, if you added a charging wire to the existing wiring, keeping the built-in charging wire, it seems to me that 8 gauge is probably overkill. I suspect a 12 gauge wire would easily work if you simply ran it from the positive battery post in the TV back to the trailer charging pin at the plug, keeping the original wire in place. You'd want to add an inline fuse to this new wire of course. The 12 gauge plus the original wire, probably no less than 14 gauge, in parallel would probably equate to 8 gauge or even larger. The larger wire doesn't hurt, of course, but it's more expensive and is harder to work with. Anyone see a flaw in my reasoning?

- Jack
 
Dee Tillotson said:
"We have always recommended firing the machine on propane, . . ."

notalines -- LOL!!! (You're kidding, right!)

Dee
Click to expand...

The refrigerator tends to cool down faster when running on propane. If you cannot hook the trailer up to 110 VAC and run the refrigerator for a few hours before leaving on a trip, it makes sense to run it for an hour or so on propane before switching to 12 VDC.

The problem with running the refrigerator on propane in a Hi-Lo when traveling is the lack of adequate venting to the outside with the trailer lowered. On conventional trailers this is not an issue. As a result, many older refrigerators were 2-way (propane and 110VAC), rather than 3-way (12VDC, propane, and 110VAC).

My first RV (18' motorhome) had a 2-way refrigerator. We would run it on propane when traveling. We always would stop before pulling into the pumps at a gas station to turn off the refrigerator and its pilot light. We would re-light it after pulling out. The only issue I ever had was the flame going out in strong crosswinds. I solved this by cutting a piece of open weave fiberglass from a household furnace filter and attaching it to the inside of the exterior refrigerator vent. This served to break up the wind a bit.
 
Refrigerator

Greg, when it comes to automotive electrical work my skills are right at the level with a box of nails so I'm not offering solutions but just want to share the problem I encountered two years ago while on a six week trip through Alaska and Canada. My 2005 Toyota Tundra was factory wired with a tow package and we were pulling a 1999 21T, running the refrigerator off the electrical while in transit. Two weeks into our trip and on a rainy day in Southern Alaska, we were ready to leave a National Park campground and the trailer battery was dead, so we could not lower the trailer. I unhooked the truck, turned it around to jump the trailer battery and we still could not lower the top. Read through the owners manual which indicated there was an in-line fuse under a bench seat. Looked, it was not there, but did find it in the battery compartment. After a trip to a distant service station for a fuse, we got the trailer lowered and drove into Anchorage and had the trailer battery replaced, which was quite old. The remaining four weeks we continued to have problems with a dead trailer battery when we pulled into a campground. It wasn't until we returned home and my son started checking the electrical and called my attention to a 30 amp fuse under the hood of the truck which was blown. Naturally, that fuse was the one that would have allowed the truck battery to charge the trailer battery while we were in transit. Like I said, I'm right there like a box of nails, but if your Tahoe was factory wired with a tow package, check your truck fuse box to see what size of fuse you have. And no, I do not know why my fuse blew.

2005 Toyota Tundra V-8
1999 21T
now 2705 T
 
Last edited:
"The problem with running the refrigerator on propane in a Hi-Lo when traveling is the lack of adequate venting to the outside with the trailer lowered. On conventional trailers this is not an issue. As a result, many older refrigerators were 2-way (propane and 110VAC), rather than 3-way (12VDC, propane, and 110VAC). "

Exactly! I believe in my owner's manual it states that the fridge should never be operated on propane while the trailer is in the lowered position. Personally, I do not believe it is safe to operate on propane while traveling under any circumstances. My opinion only. :)
 
Garry said:
Greg, when it comes to automotive electrical work my skills are right at the level with a box of nails so I'm not offering solutions but just want to share the problem I encountered two years ago while on a six week trip through Alaska and Canada. My 2005 Toyota Tundra was factory wired with a tow package and we were pulling a 1999 21T, running the refrigerator off the electrical while in transit. Two weeks into our trip and on a rainy day in Southern Alaska, we were ready to leave a National Park campground and the trailer battery was dead, so we could not lower the trailer. I unhooked the truck, turned it around to jump the trailer battery and we still could not lower the top. Read through the owners manual which indicated there was an in-line fuse under a bench seat. Looked, it was not there, but did find it in the battery compartment. After a trip to a distant service station for a fuse, we got the trailer lowered and drove into Anchorage and had the trailer battery replaced, which was quite old. The remaining four weeks we continued to have problems with a dead trailer battery when we pulled into a campground. It wasn't until we returned home and my son started checking the electrical and called my attention to a 30 amp fuse under the hood of the truck which was blown. Naturally, that fuse was the one that would have allowed the truck battery to charge the trailer battery while we were in transit. Like I said, I'm right there like a box of nails, but if your Tahoe was factory wired with a tow package, check your truck fuse box to see what size of fuse you have. And no, I do not know why my fuse blew.

2005 Toyota Tundra V-8
1999 21T
now 2705 T
Click to expand...

Thanks for sharing, Garry! I think I can say our electrical skills are the same. :confused: I think I know which fuse on the TV you're talking about. I believe it is the same 30 amp fuse that the installation directions for my Tekonsha brake controller referred to. I already had one there because I think the previous owner of my Tahoe used it to tow.

That brings up a good point - make sure you have spare fuses on board! I bought a pack of different sizes and taped it under the dinette bench where my charger-converter is.
 
Garry, I had a similar problem when we first got our trailer, brand new. Our first short trip (an overnight "dry camping" experience) was mostly uneventful except that the trailer battery was drawn down pretty heavily.

The second trip, into Colorado, to a "full hookup" camp followed by two dry camp points was quite different. The first dry camp found our trailer battery nearly dead, and I discovered the inline fuse on the charging circuit was blown. I replaced it and found it blown again when we camped the second night at a different place.

Later, I read in this forum that raising the top of the trailer with the trailer connected to the tow vehicle (and tow vehicle's engine running, so the charging circuit was connected) was likely the problem. The battery was on its last legs, due to the previous heavy discharges and raising the top put a heavy draw through the charging circuit, which was enough to blow the 30 Amp fuse that was protecting it. Essentially, the lift motor was getting its power from the TV battery, and the draw seems to be greater than 30 A.

This is different than what happens if you try to raise the top, with a dead battery, using shore power through the onboard converter. The circuitry in the converter simply does not deliver the 30+ Amps needed to power the motor.

So, I've learned to ALWAYS disconnect the trailer's power cord from the TV before raising the top to protect the charging circuit fuse. I've not had a blown fuse problem since then. I think simply shutting off the TV's ignition would provide similar protection, but it's just as easy to pull the plug.

- Jack
 
Greg, I doubt that your trailer charging circuit and brake controller share the same fuse. I know they don't on my Ford. Check your owner's manual for the fusing. In my Ford, the trailer charging circuit uses a special, 30 Amp fuse that is quite different than any of the other fuses in the fuse box. (Which means I have to carry these different sized/shaped fuses as spares.)

- Jack
 
Well that is a handy piece of information. I often raise the trailer while hooked to my tv, especially at dump stations though I usually have the engine shut off. Have not blown a fuse yet, I don't think. I guess I should check.
 
JackandJanet said:
Rich, regarding the size of the wire, if you added a charging wire to the existing wiring, keeping the built-in charging wire, it seems to me that 8 gauge is probably overkill. I suspect a 12 gauge wire would easily work if you simply ran it from the positive battery post in the TV back to the trailer charging pin at the plug, keeping the original wire in place. You'd want to add an inline fuse to this new wire of course. The 12 gauge plus the original wire, probably no less than 14 gauge, in parallel would probably equate to 8 gauge or even larger. The larger wire doesn't hurt, of course, but it's more expensive and is harder to work with. Anyone see a flaw in my reasoning?
- Jack
Click to expand...

Jack, I didn't consider the existing charge wire, so running a parallel wire would allow a lighter gauge. Doing that, would you tie into to where the existing wire leaves the the fuse/relay or would you tie into the battery with a separate breaker/fuse? I can see a possible fusing problem by hooking to separate power sources. My original idea was to replace the factory charge wire.
 
RichR said:
Jack, I didn't consider the existing charge wire, so running a parallel wire would allow a lighter gauge. Doing that, would you tie into to where the existing wire leaves the the fuse/relay or would you tie into the battery with a separate breaker/fuse? I can see a possible fusing problem by hooking to separate power sources. My original idea was to replace the factory charge wire.
Click to expand...

Hi Rich -

I think it would be difficult to tie the new, parallel wire into the fuse box, at least it would be on my truck. I'd attach the new wire to the positive terminal of the battery and run it back to the trailer plug.

You're right, though, the fusing could be tricky. In my truck, the trailer battery charging line has a 30 Amp fuse installed. You probably don't want to allow more than 30 Amps to flow through the new setup. If I left the original line in place, I'd probably try to install a smaller fuse, say 15 Amps in the original line and then put another 15 Amp fuse in the new line. You could probably increase the total to 35 Amps without much danger, but I wouldn't go higher.

It may not be possible to find a 15 or 20 Amp fuse that would fit the fuse box - I haven't looked, since I haven't made this "mod". If that's the case, it would be best to totally replace the existing charge line. I'd do it with a wire from the positive battery terminal to the trailer plug and an inline fuse near the battery. Then simply remove the original fuse box fuse to disable the original charge line. (This assumes that line does not run anything else - on my Ford, it doesn't.)

The only downside to having a wire from the battery to the plug is that it is always "hot" and not switched with the ignition. I don't see this as a serious problem though.

- Jack
 
JackandJanet said:
Greg, I doubt that your trailer charging circuit and brake controller share the same fuse. I know they don't on my Ford. Check your owner's manual for the fusing. In my Ford, the trailer charging circuit uses a special, 30 Amp fuse that is quite different than any of the other fuses in the fuse box. (Which means I have to carry these different sized/shaped fuses as spares.)

- Jack
Click to expand...

Thanks, Jack. I probably just assumed the brake controller was the same circuit as the charging circuit. I'll double check the Tahoe to see how it's fused.

Before going to the trouble of adding or replacing the charging wire, I think I'll go on a few campouts to see if there is an issue.

How would I check to see how much amperage I'm getting back to the fridge? I do have a multimeter but am somewhat electrically challenged so specifics are welcomed! :eek:
 
JackandJanet said:
The only downside to having a wire from the battery to the plug is that it is always "hot" and not switched with the ignition. I don't see this as a serious problem though.

- Jack
Click to expand...

You could put a relay in line switched by the ignition switch.
 
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