Truck inverter to power camper fridge

[AnEv942]

Running fridge on AC from trucks inverter...
Not a how-to, certainly not a recommendation- cut every corner I could with a ton of round to-its.
Just what I concluded and installed...may or may not help anyone but another thread caused me to realize
I could run fridge on higher wattage AC if I added inverter, existing wiring would work and control fridge.

Problems- If inverter AC (or other source) not available fridge goes to 'check'. (which requires, on mine, resetting
fridge even if power restored)

As fridge board 'remembers' and will reconnect to last selected source, simply turning off fridge or 12v power to
board and reconnecting when source power to be available will keep fridge from going to 'check'.

Easiest method, when shutting down truck is to run inside camper and shut off fridge. Turn back on when source
power to be restored. Or adding a toggle somewhere outside that is more accessible to turn fridge on/off.
3rd, use relay on fridge main 12v supply, trigger/controlled by truck ignition or manual switch.

As I already have ignition controlled relay set up 10 years ago (been using DC for 20 years) if I added an AC
source I'd have option to run AC or DC, good to go. My ignition trigger goes thru dash switch to enable or disable.
(Note: If using relay, a bypass switch will need to be used when camped or as I did, a selector switch that
determines source of relay trigger wire)
___________________________________________________________

All that out of the way, installing the inverter.
Least expensive I could find-1000 watt modified sine. Expected use ~350 watts. Test with 600 watt heat gun.

Hurdles:

• Location of inverter,
  
• Routing inverter AC out to camper
  
• Routing battery cables inside truck to inverter from engine bay
  
• Hardwire camper/Fridge selection of AC source

Location:

My only option was behind drivers seat on rear wall. Required making brackets to hang inverter.

Under window is formed sheet metal box. Only place to attach. Brackets hold inverter out an inch from back wall, with 1/2" gap at top 1/4"
above bottom formed carpet bumpout that brackets set against.


Inverter mounted. Already decided I'm mounting a bed receptacle, camper will plug into it. Though temporarily used an extension cord to
plug in fridge. A 14ga cord out from inverter, cut off female end and routed thru existing rubber plug at truck back wall. Cord goes out
under and up between bed walls to make connection at bed receptacle.

Routing inverter AC:

Bed receptacle was a puzzle as most RV AC pre-made stuff is going in wrong direction, truck is hot side. Need Fixed live female on truck,
umbilical the male (can never be made hot). Standard wet location box with an in use cover just too big.

Going thru parts found this in use wet location box. Intended for a pole light -perfect just had to trim curved back.
Shallow- weather proof in-use.

I looked all over and could not find another to purchase but for bed mounting ideal. Shear luck.


UPDATE 06/2020- stumbled across source- Solus SCO-930BK 120V Grounded Convenience Electrical Outlet w/Rain Shield for
Outdoor Lamp Post and Poles, Energy Saving and Weather Resistant
Amazon link as long as it lasts https://www.amazon.com/dp/B07XTNRM5H

Routing 4ga battery cables:


This hole in floor covered by rubber boot leads to area that's inside double wall floor, boxed. About 6" to left on other side of box is an
identical hole. It allows cable to enter from engine bay, make a relaxed S turn that lets cable lay flat once it enters cab. Located between
clutch and brake and not anywhere near boot movement.
Route around seat and up rear wall to inverter,

Once routed pulled excess into engine bay.

Once I had cables into cab cut and added inline fuse holders to fix lengths. Plan is to get some loom material, fully cover cables and a
dozen or 2 zip ties. However holding off until I decide how to add lugs to cables and replace fuse holders. These work well, easy to use on
cut cable,no lugs required- but I just don't trust them. Not wanting to pull cables so may pick up crimper. roundtoit.

Inverter mounted, battery cables run, inverter cable run, bed receptacle mounted. Last is to hard wire camper but waited until we returned
from week out to ensure this works before spending energy to wire camper.

Used an extension cord plugged into bed receptacle, draped across front of camper and thru fridge cover.

And it worked!. Surprisingly well, way better than hoped for. We had the fridge remote thermometer inside truck to watch temps...


Hardwire camper/add split receptacle at fridge


Again, cut off female end of 14ga cord. Drilled hole, installed plastic grommet and pushed cable into camper leaving about 30" outside.
Routed inside across water tank.

Under floor of slide to existing cable hole of slide that enter seat box. This leads into outside cabinet that is beside refrigerator


Poked thru to fridge. Removed boxless receptacle, install new box.


Wired new receptacle as split, 1 source camper the other truck.
Switching AC source will be a matter of plugging into desired source. Our normal would be truck.
Swapped the fridges right angle pigtail for shorter straight plug. Labeled- done.

Well, convert the fridge cover to hinged for easier access...
http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/29974858.cfm



Added power strip for ease of access and other stuff that might be used.


Had to replace compressor switch in dash. Used drill and heat gun on the wiring. Nice. Also tied the dash inverter remote switch thru
ignition triggered relay to turn off inverter if I forget. Though inverter can be used without engine on by using its case mounted switch
could quickly lead to dead batteries. The fridge is ignition triggered and goes off with ignition so no real load but just extra measure...

[Kayteg1]

I always look at the pictures of burn RVs and you can get pretty good guess what happen.
Modern RV are build with materials who will smolder, but will not make hot flames.
Lot of pictures ( I posted few just weeks ago) of refrigerator fires, who will consume side and ceiling above refrigerators, but seems either they die on their own, or are easy to extinguish.
It takes propane piping rupture to start big flames, who will generate hot fire blowing tanks and results that you can see on the picture.
Few youtube pictures show that Fire engines are not even coming close to hot RV fires in fear of tank and tires blows. They just let it burn.
Bottom line, I always had fridge operating on 12V in motorhomes and propane off at the tank.
Now with TC supplying 12V power via original wiring is not adequate and that is why we have topic's modifications.

[ticki2]

Kayteg1 wrote:
The "why drive with flame under the fridge to gas stations?" disputes seem to never end.
Lately I found new pictures so use it to trigger your imagination.
Here is 1 year old motorhome, who was driven with open propane tank.


Click For Full-Size Image.

.

Unless one knows the back story there is no way to know what caused the fire . A dead shorted battery or loose electrical connection could have the same result . Certainly not all RV fires are caused by propane .

[AnEv942]

Kayteg1 wrote:

What's wrong with running factory inverter at full load?

Though a little confused by Fords 400 watt rating and 300 if running (usuallly peak is X2 of constant load so not sure what they are referring to?. my understanding is rating of inverter should be intended load plus 10-20% above that. If the constant rating is truly 300watts and fridge heater is 325 that would be over its rating-if 400 very close. Whether harmful or affect longevity I dont know, I would assume factory inverters not inexpensive to replace.

[AnEv942]

Interesting-different operation modes than ours. Can not select AC without going into auto. DC can only be manually selected (wont connect to DC in auto mode if AC or gas unavailable).


Operational pages 9 and 10


As this isn't (wasn't) about the morbid fears of electricity or gas, why I/you should do this or that- just options and what I did don't feel a need to justify my decisions..so am not. If info can be gleaned from my original post by someone attempting similar project great, if it convinces them, thats dumb and not do or do differently- great. What I didn't intend was start another 'propane wars' thread.
Just find it curious sometimes folks seem to need to defend thier position /conclusions when it wasn't challenged?

[Kayteg1]

Grit dog wrote:

But having the valve open is not the cause of a propane explosion.

Right, typical situation on motorhomes is the flat tire ripping inner fender, where propane lane rest, breaks copper tubing and spark from the rim hitting the pavement starts the fire.
Once the fire gets really hot, that's the time when tank explode.
We all accept different levels of hazard and danger.
For me running 120V cables between the cabin and camper is another hazard and that is what is stopping me from running the cable.
Would I do the project, I would pull a rubber hose or something over the cable where it runs between cabin and bed.

[Grit_dog]

^This
Or in short, the whole inverter setup etc is the long way around a short trip.
Besides, propane tanks don’t just spew gas wildly if the hose gets cut.
Check valve stops the flow if the flow rate exceeds a certain rate.
Ever open a tank valve too fast into an empty line and hear the click and no gas?

Now if the valve fails or the tank physically damaged, sure a propane tank can go up.
But having the valve open is not the cause of a propane explosion.

[Bedlam]

My last fridge was three way and would switch back forth between AC and LPG on the automatic setting without a problem. If AC and LPG were not available, it would switch to DC but would then stay there until you manually switched it out of that mode. I could run the fridge in manual mode choosing my source so it would not switch over but had to be careful with the automatic setting. Once while driving in high winds, the LPG flame blew out and it switched to DC and another time I ran out of LPG and it switched to DC. My previous camper did not have solar and only had the small charge line on the 7-blade connector, so I was drawing more than I was replenishing from the truck.

Running AC or or heavier DC from the truck would have solved my previous problem but by the time I experienced it the the first time, I already had upgrade plans for the truck and camper...

DC source was convenient for restricted LPG use areas like tunnels and ferries, but I passed on the option this time. I like some of the compressor fridges offered but still have a hard time justifying the price. Perhaps if my absorption fridge fails, I will revisit that option. Although I have seen some of the pictures of LPG fires caused by appliances, I am still confident in my systems to use them while driving.

[Kayteg1]

The "why drive with flame under the fridge to gas stations?" disputes seem to never end.
Lately I found new pictures so use it to trigger your imagination.
Here is 1 year old motorhome, who was driven with open propane tank.


Click For Full-Size Image.


Click For Full-Size Image.

[AnEv942]

Simply a matter of choice not using gas on the road. Many do-we don't.

Fridge behaves as designed.. To use AC fridge must be set to 'Auto'. What it actually does, being set to auto to use AC, is if AC unavailable (engine/inverter shut off) control tries to connect to gas. If propane off it cant and after a few attempts goes to 'check'. Once in check mode has to be reset. If AC restored before it searches for gas then goes to check it reconnects to AC. But that happens faster than reason for turning off engine IE fueling, eating lunch etc. Turning off 12v to control board when AC turned off keeps fridge from seeking alternate source.

As Kayteg1 asked about- if AC could be manually selected like gas or DC would be no issue.

[PNW_Steve]

Curious, why don't you run the fridge on propane while underway?

I also wonder why your fridge misbehaves when 120v power is interrupted. I have owned a handful of RV absorption refrigerators and don't care for them. Their one redeeming quality is the ability to run on propane. I never had any issues with bad behavior when switching between 12vdc, propane and 120vac.

I suspect that your control board in the fridge may be failing.

If you are not using the propane capabilities you may want to consider replacing your fridge with a conventional fridge. They are MUCH more efficient on 120v than the RV absorption fridges. The 10.8 cu.ft. fridge I installed in my current 5er uses less than half the power that the 6.8cu.ft. unit that it replaced. I did have to make a minor modification to the cabinet. Not a big deal.

FWIW: I put 300 watts of solar on the roof. It is almost enough to keep the fridge happy. I had intended to put 600 watts up but the roof had too many obstructions.

[Kayteg1]

AnEv942 wrote:
.. But again I question using factory inverter, everything Ive read shows 300 watts max while driving. Even IF 400 watts available, at 325 watts of fridge AC heater+, inverter would be running near full load?

What's wrong with running factory inverter at full load?
So far I tested the inverter with 2.5A air compressor and it starts under the load just fine.
I am also thinking about making idiot-proof cord that would unplug itself in case I forget.
Getting older sucks and better be prepared ...

[AnEv942]

Work2much: Ya that was kind of my conclusion as far as cabling, plus previous mods led me to this route. If starting from scratch might have done differently. Inverter power to camper is solely dedicated to running fridge. The other factor and real motivation, was simply wanted an inverter in truck.

Kayteg1, there are several options as far as auto switching and was really on the want list. I may revisit, be nice upgrade project if this gets old but probably not. We move plugs inside camper from shore to inverter use, not a real inconvenience. Still would be nice.
Must be someplace between inverter and dash you could tap, add another receptacle, short cord to bed. But again I question using factory inverter, everything Ive read shows 300 watts max while driving. Even IF 400 watts available, at 325 watts of fridge AC heater+, inverter would be running near full load?

[Boatycall]

I'm doing something similar, but a different approach. I have a Magnum Technologies 3kw Inverter/Charger permanently hardwired into the TC. It has a built in transfer switch and is intended to cut the shore power cord and run the whole TC when activated.

I turn on the inverter, fridge kicks over to 110v.

I then ran a set 4ga cables from the truck batts to the camper batts, through 100amp breakers at each end.

When I get where I'm going to park, I trip one of the breakers to disconnect the truck batts from the TC.

I also have 800watts of solar on the roof, so on a sunny day, I run the fridge off electric also. On a sunny day, I can peak-out my solar controller at 60 amps charge. Fridge heater is a 400watt element, that comes on and off on a as-needed duty-cycle so keeping up on solar is no problem.

[work2much]

Nice report. I have been kicking around the idea of installing an inverter in the truck that could be used to power the camper, charge the battery etc while driving. It seems like a good alternative to running large dc cables for battery to battery charging.