Vehicle Portable Battery Options for Keeping a Dometic CFX 40 Refrigerator Charged

Trailguy

New member
I checked all through the FAQ's to find an answer for what I am trying to accomplish regarding battery back-up solutions. Hopefully someone can point me in the right direction.
While on trips, I would like a portable battery system to keep my Dometic CFX refrigerator charged when it's not plugged into my truck with the truck running. I would like the system to be easily swapped from my Tacoma to my LX100 Series. I'm also open to a portable solar panel to be used in conjunction with the battery.
I'm simply trying to keep the fridge running when the truck is not, and without having to purchase two separate dual battery systems for each vehicle. I looked at the Goal Zero options (very pricey) and the REI folks couldn't steer to a model that would keep the fridge charge for a day or two.

Thanks in advance for your suggestions.
 

john61ct

Adventurer
The ready-made portable powerpaks are all poor value IMO, either, poor quality, too expensive or (usually) both.

Really it's a battery in a box, plugs and gadgets, best to choose what your use case requires.

Figure out how many usable Ah @12V you need, how many hours' or days' storage between charges, how big a difference between fridge temp and ambient are the major factors.

Cheapest is rig a handle for a G31 AGM, gets you 50Ah usable, but heavy and bulky.

LFP is 4-7x more expensive but can last longer, more portable.
 

whitenoise

Adventurer
A portable power pack isn't cost effective, like you've found already - you may have to spend $600+ to get a good one with enough capacity. On the other end of the scale, you also don't need dual battery systems as long as:
  1. Fridge doesn't have to run without starting the engine for more than about 24 hours. If it exceeds 24 hours, use portable solar to charge. A 100W panel is likely more than enough unless you're in Alaska.
  2. You use the inbuilt LVD (low-voltage disconnect) feature on your fridge correctly. OEM power outlets are wired with small gauge wire that causes a big voltage drop, enough to trip the LVD without the battery actually being flat. You may have to run a dedicated 10AWG line on a 10 or 15 A fuse from your existing starter battery to the fridge in each vehicle.
  3. You buy a proper lithium jump starter and move that with the fridge between vehicles.
  4. The battery in each vehicle is a high-quality starter or deep cycle AGM with at least 90Ah capacity.
  5. You aren't traveling hundreds or thousands of miles away from civilization (for example the Sahara Desert) where a catastrophic battery failure might be a life and death situation.
 
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Trailguy

New member
Thanks Whitenoise, I have already determined I need to run dedicated wiring from my battery via BlueSea fuse block on my Tacoma. I have already done this on the LX470. I plan to run the dedicated wiring on the Tacoma this weekend. Then plug in the fridge to the new power source and see how long the fridge will run on my current battery without it going dead. Also, to make sure the LVD settings do in fact shut down the battery power with enough juice to start the Tacoma.

I may look into a Solar back-up system to keep the battery topped off as well. I’ll have to check into those systems as well. Seems like a lot of guys use the Ctek or Red Arc systems. FYI I do have a small Lithium battery jumper, but I don’t like the idea of having to use it.
 

whitenoise

Adventurer
Theres plenty of lithium jump starters available these days, and the majority of them are of questionable quality. The ones from Antigravity and Noco are really the only types that I would trust. My XP10 Antigravity is a trooper, having started big v8s over and over again when the main battery was completely dead. It took 5+ tries of heavy cranking for the charge to go from full to almost empty.

Sent from my Nokia 7.1 using Tapatalk
 

john61ct

Adventurer
Little jumpstarter powerpacks have high amps for a second or two

but not enough Ah to keep a fridge going for long.
 

pluton

Adventurer
Wouldn't one be able to connect the starting battery with heavy cable directly to a matching size and type house battery, thereby creating, effectively, one large battery that has double the capacity of either battery alone?
 

john61ct

Adventurer
yes but depending on length may require so heavy to counter Voltage drop, as to be impractical

And a VSR or LVD between is required to prevent House loads from running the Starter down.
 

Trailguy

New member
To clarify, my thought was to use the lithium battery jumper only if the main battery voltage was so low that it would not start the truck. This would mean the LVD settings on the Dometic CFX cooler did not shut off power to the cooler with enough reserve on the main battery to start the truck. I plan to do this in my garage to ensure I know what to reasonably expect out in the field.
 

whitenoise

Adventurer
Trailguy - I've had great luck with a single Group 49 in a 100 series. Pretty simple and sub-$200 install if you're going to replace the stock cranking battery.

Here are some old posts for your reference:



Sent from my Nokia 7.1 using Tapatalk
 

Ace Brown

Adventurer, Overland Certified OC0019
A portable power pack isn't cost effective, like you've found already - you may have to spend $600+ to get a good one with enough capacity. On the other end of the scale, you also don't need dual battery systems as long as:
  1. Fridge doesn't have to run without starting the engine for more than about 24 hours. If it exceeds 24 hours, use portable solar to charge. A 100W panel is likely more than enough unless you're in Alaska.
  2. You use the inbuilt LVD (low-voltage disconnect) feature on your fridge correctly. OEM power outlets are wired with small gauge wire that causes a big voltage drop, enough to trip the LVD without the battery actually being flat. You may have to run a dedicated 10AWG line on a 10 or 15 A fuse from your existing starter battery to the fridge in each vehicle.
  3. You buy a proper lithium jump starter and move that with the fridge between vehicles.
  4. The battery in each vehicle is a high-quality starter or deep cycle AGM with at least 90Ah capacity.
  5. You aren't traveling hundreds or thousands of miles away from civilization (for example the Sahara Desert) where a catastrophic battery failure might be a life and death situation.
That’s essentially my program and it’s never failed me in nearly ten years. I have had to replace two starter batteries but both under warranty.


Sent from my iPhone using Tapatalk
 

john61ct

Adventurer
So we're not discussing this topic anymore?
I would like a portable battery system to keep my Dometic CFX refrigerator charged when it's not plugged into my truck with the truck running. I would like the system to be easily swapped from my Tacoma to my LX100 Series.
Maybe better to start a new thread to avoid confusion?
 

nixid

Observer
IS there a recommended controller that would work with both the house and starter battery connection and also for solar input? Could he use some quick connects and just move the battery, controller, frig and solar panel from vehicle to vehicle?
 
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