I am considering purchasing a 12v, 10cu.ft. refrigerator as a replacement for the AC/LP unit in our trailer. I want to run the fridge while traveling (max 8 hours or so). Trailer battery is (1) 12v AGM true deep cycle, 100ah. (I realize I essentially have a dead battery if I discharge under 50%)

I don't have solar on the trailer to help out with charging during transit and am wondering if my truck ('19 Super Duty w/240 amp alternator) will provide enough charge during travel to ensure I have a useable trailer battery when I get to my destination. We don't boondock, always full hook-ups, so will be plugged in to shore power except during travel, allowing the trailer's converter to take over charging duties.

Side note: Power consumption on one fridge I looked at was listed as 1.08kWh 'per day'. Real dummy on this, but If I understand my Googling correctly, I believe that would break down to 3.75ah, per hour of use. So with 8 hours of travel I would be using 30ah of the battery......less whatever my truck charging can put back.


Thanks

 

Also keep in mind, start off with a cooled refrigerator, it will not need to run the whole time. I don't think these trucks put out much, but you are not asking for much either. I'd do it, worse case you have to add a second battery.

 

Quick google search for a 12v 10 cu.ft. rv refrigerators indicates a current draw of 8 - 15 amps depending on the manufacturer (Dometic, Furrion, Norcold). The 2019 Ford Super Duty manual indicates the trailer tow battery charge circuit relay protected by a 30A fuse. So I wouldn't imagine you would have any issues with that setup.

 

I have a 2020 travel trailer and 2020 F150 connected via 7-pin and the truck fully recognizing the trailer attached. We have a bluetooth camera on the back that requires turning on all the trailer lights/markers to receive power and so I put my F150 lights in the parking light setting whereever we go. I have a 120V / LP dometic fridge in there that is turned off but we find that by pre-cooling and fully stocking before trips it lasts several hours this way.

The point of telling you the above is the battery on my trailer slowly drains in this setting of trailer lights but no fridge. When I arrive after a long (3+ hour) trip my battery conditon is good but not full, and the 120V AC -> 12V DC inverter fan whirs up to the full constant charging mode and not the topping charge mode when I first connect to shore power. I haven't investigated if this is a problem/malfunction with my truck and trailer combo or just the reality that the 12V current from my trucks alternator is insufficient to maintain the battery at a full state of charge. I suspect its due to the resistance across that distance of 12V wire causes the voltage to drop beneath the voltage of the trailer's battery thus not really sending any energy to it (until eventually the battery starts to get really low).

I've read that 12V fridges are a bit of a boondockers nightmare with several posts on rv forums about their single lead acid battery barely lasting the night.

 

Thanks for the info.

I live in AZ and although I cool my LP/Electric fridge 36 hours or so before loading and ensure food placed in the fridge is already cold, I still arrive after travel with a 50 degree or higher temp. My fridge is mounted in the kitchen slide, which is notorious for being problematic for cooling. Even with the addition of an extra fan to direct more hot air to the upper vent. My fridge is also not thrilled with running on propane when traveling....it invariably shuts down at some point, requiring a reset of the thermofuse when arriving, in order to get it fired back up. In addition, wife is not a fan of traveling with propane on anyway.

I too have a back up camera on the trailer that is always on when towing and arrive at 'camp' with a fully charged battery...perhaps the Super Duty alternator (I have what is termed in the option list as the 'Extra Extra Heavy Duty Alternator') provides more of a charge? I dunno...

We do not boondock and do not anticipate it. We are full hook up 'glampers'. Only time I would be running without being plugged in to shore power (and thus having the converter do its thing) would be while in transit.

 

Mister C said

Charging While Towing

I am considering purchasing a 12v, 10cu.ft. refrigerator as a replacement for the AC/LP unit in our trailer. I want to run the fridge while traveling (max 8 hours or so). Trailer battery is (1) 12v AGM true deep cycle, 100ah. (I realize I essentially have a dead battery if I discharge under 50%)

I don't have solar on the trailer to help out with charging during transit and am wondering if my truck ('19 Super Duty w/240 amp alternator) will provide enough charge during travel to ensure I have a useable trailer battery when I get to my destination. We don't boondock, always full hook-ups, so will be plugged in to shore power except during travel, allowing the trailer's converter to take over charging duties.

=== ===

As discussed in many threads

Do not plan on using power from the 7pin because it just will not work. Just run a 12v fused circuit from the truck battery to the trailer just like all the flat tow guys do. You will obviously have to add another connector between the two rigs. Your alternator will provide plenty of power for the fridge.

 

https://www.f150forum.com/f82/camper...fridge-497885/

 

Put a DC-DC regulator on your aux input.

 

I've tried to research this separate charging line issue and it seems to be one of the single most confusing topics for something that would seem like it should be simple. Articles and posts I've read run the gamut from 'you don't need to do anything' to you need to 'install a $400 DC to DC charger'. Very confusing for a dummy like me!

To be clear on your method.........Are you saying I would literally run a single wire, from positive battery terminal to positive battery terminal, with an inline 30 amp fuse installed close to the truck battery side? What size wire?....I've seen 10 gauge thrown around in a few articles? By 'another connector', assume you are referring to a male end on trailer/female on truck type deal, to use as a means to quickly connect/disconnect this length of wire?

Thanks

 

It is confusing because most folks do not understand how the 12v in the 7pin works.
I ran two wires from the truck battery, + and -. Find the wire/fuse sizing use Google based on your current draw and distance for the wires. Without looking it up for 10 amps it probably be around 12 ga and 20 or 30 A fuse for 15 or so feet.
I have 2 pin connector wire to the trailer or other towed rig just connect the wired to its battery. The result the the trailer will see the same voltage as the truck and when you are thru driving you battery will be full and at the same voltage as the truck.
A dc-dc charger is very expensive and not needed for a simple fridge and accessories on a travel trailer. The dc-dc charger is for a higher load and something that requires max voltage instead of the ford reduce voltage setup. Typically the maintain 14+ volts and have at least 25 Amp capacity.
The main thing for a Ford is to avoid the +12 from the 7pin source.
Most flat-tow folks including me use a 6pin connector for lights and the 12v feed. 4 pin goes to 6pin like the 2 wires from the battery.