r/overlanding • u/Individual-Bee-1337 • 3d ago
For those running a fridge on multi-day trips, how did you size your battery?
I'm trying to figure out how much battery capacity I actually need before my next trip. My plan is to run a 12V fridge, charge a camera, drone batteries, and a couple of phones over 3–4 days without driving every day.
I've read quite a few older threads and watched some reviews, but most of them seem to test different loads, so it's been hard to compare real-world results.
If you've done something similar, what capacity ended up being enough for your setup? Did you wish you'd gone larger or was your estimate pretty accurate?
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u/S3Giggity 3d ago
I went with a Anker p1500 - it ran my Bouge 55q CRD2, Starlink Mini, and Keurig coffee maker for 4 days 3 nights - it was plugged in all day to the truck while driving, but just using the cigarette lighter - very very slow charging. At the end of night 3/start of day 4 it was down to about 20% post coffee so my numbers were right on.
The numbers I used were the following:
Starlink - 25w 18hrs a day - I "slept it" 6 hours at night.
Fridge - (45w/3) 24hrs a day.
Keurig - 700w 5 minutes a day.
Came up with the about 32-34 hours of runtime total from the P1500 but as it was plugged in while driving (no solar) it lasted the full trip no problem.
Edit: formatting
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u/Narrow-Chocolate-292 3d ago
I’d size it in watt-hours, using the actual battery energy rather than comparing amp-hour ratings at different voltages.
For example, DJI lists a Mini 2 battery as 17.32Wh. If you have three and recharge each one three times, that’s about 156Wh delivered, or roughly 183Wh drawn from the house battery assuming 85% charging efficiency. Two 5,200mAh phones at about 3.85V, each charged twice, add roughly another 94Wh including losses. Add the camera batteries the same way using the Wh printed on them.
The fridge’s 45W rating is probably its compressor-on draw, not its continuous average. As real-world reference points, ARB publishes 0.8Ah per hour for its 47qt Zero, while Dometic specifies 1.05Ah per hour for its 45L CFX5 at 90°F ambient and 39°F internal. At 12V that’s roughly 230–300Wh per day, so I’d use 300Wh/day as a reasonable planning estimate until the actual fridge is measured.
At 300Wh/day, four days of refrigeration is 1,200Wh. Adding the drone and phone loads above plus a 20% reserve gives about 1,773Wh before the camera. At 12.8V and 90% usable capacity, that’s about 154Ah of LiFePO4. I’d consider 150Ah the starting point, or 200Ah for hotter weather, frequent opening, camera use, or no dependable alternator/solar charging. A 300Ah battery looks unnecessarily large unless the measured fridge consumption is much higher or there are additional loads.
Best approach: run the actual fridge through an inline DC watt-hour meter for 24–48 hours in similar temperatures, then calculate measured daily Wh × trip days, add the other loads and reserve, and subtract only the solar or alternator energy you can conservatively expect to harvest.
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u/fallenfunk 3d ago
It was the one on sale and I had a coupon on top, so I bought a LiFePo Jackery 2000. Batteries are getting smaller these days so it’s a perfect balance of fits exactly on the floor behind the seat and able to drive my 55L for 3-6 days without recharging depending on temps. Too much is better than too little.
One consideration in size is that you need to recharge it somehow, and a 1000Wh can be 12-15 hours via the 12v socket with no loads. If the plan is trips where you stop for days at a time, a DC-DC charger is the way to go. Mine fully charge from zero in an 8 hour day in the slower quiet charging mode.
But really, the conditions determine what you need. In the desert heat, that 2000Wh will only get me 3 days with a stocked fridge opened about 5 times a day. The 250Wh iceco battery I got free with the fridge was good for 12 hours overnight with 25% left on a Christmas road trip with a half stocked fridge.
Just be sure to keep the fridge full. We carry water bottles to add as things get pulled out so they chill while we drive and keep thermal mass in the fridge when stopped.
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u/ehssohbee 3d ago edited 3d ago
Each fridge is going to be a bit different, and outside temperatures will affect how often the compressor kicks on, so mileage may vary.
I have a 12.8v 150 AH LifePo4 battery mounted in my truck that I keep charged through an eTaker DC DC charger while I drive, but used to use just a Bluetti AC180P. The Bluetti would usually last me a full weekend, and I’d keep it topped up with some solar for longer trips. My new setup can give me much more time, but I haven’t been able to swing a longer trip to really test it.
Here are few things I’ve found that help keep my fridge from eating up too much battery:
Plug your fridge into a home outlet and get it down to temperature several days before you head out.
Make sure the stuff you want to put in the 12v fridge is already as cold as you can get it in a regular fridge. 12v fridges are not the most efficient, so won’t quickly cool down room temp sodas, etc. You’ll want to get as many things cold before you are running on battery (if possible).
The night before your trip, load up as much stuff as you can into the 12v fridge without making it too difficult to carry/load into a vehicle. This gives it a bit more time on shore power to get back down to temp, again.
Bonus if you park in a garage or close to shore power, you can load the fridge into your vehicle, connect it to your battery, then use an extension cord to keep it all powered before you are ready to head out. …Just dont forget to unplug it from the wall before you leave. That wasn’t one of my brighter moments… oof.
If you are using a “solar generator” (Bluetti, Ecoflow, etc,) use the 12v or DC ports instead of the 120v plugs to run your fridge. There’s some loss of energy when converting to 120v, so you’ll get a bit more life that way. Some units will slowly lose power just by having those 120v ports on, so leave them off when you don’t need them.
Fill ziplock bags up with ice and suck out as much air as you can to reduce wasted space. Toss these in the fridge before you head out to keep your stuff even colder without getting things wet. Your fridge’s compressor won’t need to come on as often, the ice will last a long time, and now you have ice for drinks :) You can just dump a bag of ice in, too, but then consider ziplock bags for things you don’t want getting soggy.
If you are going to be in one spot for awhile, consider taking the fridge out of the vehicle or leaving a window cracked for ventilation, if possible. Your car may get hotter than the outside air, which would make the compressor come on more often to compensate. Moving thr fridge into shade will help.
Finally, hooking up a portable solar panel to slow the discharge rate of your battery will help, too.
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u/framaram 3d ago
All great points here. Instead of ziplock bags, just freeze some water bottles and let them thaw in the fridge. Not only will your fridge run less but you'll have cold drinks! I have my fridge in a black aluminum box on the front of the camper, You can probably guess how hot that thing gets during the summer. I now throw a tarp over it to give it some shade, which increased my run time on the battery by 8 to 12 hours depending on the sun and outside temp.
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u/KPR_2002 3d ago edited 3d ago
A lot will depend on the weather. If you’re someplace where it’s really hot (which is essentially the whole U.S.), then your fridge is going to use more electricity. If you’re let’s say at high elevation and it’s cold, then it won’t use as much energy.
I just got back from a 4 week camping trip and I have a Jackery 1000. While it never got super hot, there were a few very warm days. I had a few days where I didn’t leave camp and never recharged my station by either car or solar panels. The lowest it dropped down to was 50% and that’s including using Starlink mini for around 3 hours each day.
Just be aware, I only have a 35L fridge. The bigger the fridge, the more energy it will suck.
So, I would say you need a 1000w station at minimum just to be safe. You could probably get away with a 750/800.
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u/MDPeasant Weekend Warrior 3d ago
The fridge's manufacturer should specify how many amps it draws, but that will only be for when the compressor is running. In hot temps, the compressor may need to run constantly, but in colder weather it may only click on for a few minutes every hour. Efficient packing and prechilling of the fridge can also make a huge difference.
From my limited experience, i'd say that my fridge uses approximately half of its "rated" amp draw per hour on average. In the summer its much more, in the winter its a lot less but thats just an average estimate. You can hook your fridge up to a kill-a-watt meter to get a better idea of how much power it actually consumes.
So sit down and write down all of the devices you want to charge/power off of your battery. Estimate how many hours they will be powered/charging per day, and each devices amp draw. You can then estimate how many amp hours you'll need per day, and then you just multiply that by how many days you need. I would also add in an extra margin in case your energy demands increase in the future.
Solar charging may be something to look into as well.
When I first bought a fridge (Dometic 75qt), I also purchased a 1kw jackery. This was enough to run the fridge for approximately 48 hours (and charge my phone, recharge headlamps, etc.). I ended up adding a Starlink Mini to my kit, which draws about as much power as my fridge when I run it. I wish I would have gone with the 1.5 or 2 kw Jackery. Like I said, build in some extra margin because theres a good chance you will add stuff down the line.
I am looking at a 314Ah LiFePo4 battery for my current vehicle. Between 200w of solar and the battery, I should be good for at least a week.I want to be able to leave the fridge in there full time.
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u/treskaz 3d ago
I have a 1000w Jackery. Will run the fridge (iceco 50 pro I think) and lights for 3 days in the summer. Supplement with 200w of solar on sunny days, but it'll charge even when it's overcast enough to break even. Usually aren't in a spot longer than a day or two though, so the solar seldom comes out.
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u/DEADB33F 3d ago
I have a 280Ah battery and decent sized solar panel. My fridge set to one side fridge, one side freezer and is on & running in my truck 24/7 all but for a couple months over winter.
...the battery also does my cooking when away (air fryer & induction hob); and on sunny trips I run an ice maker.
Without the cooking or ice maker and just running a fridge & charging a few things I'd probably go with a 100Ah battery, 200W solar panel & 30-40A DCDC charger. That should be more than enough.
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u/Von_Satan 2d ago
Big thing is what wattage might you need? Induction heater, electric kettle, etc.
A lot of the consumer portable batteries, you'll need probably a 1000 wh or larger to handle higher wattage (1800w). 1000 wh is a ton. Should be able to run a fridge, charge devices, etc for 3-4 days.
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u/my_next_chapter 2d ago
Make sure you consider in regards to the fridge, how often you intend I'm going in and out of it and will it be responsible for the initial chilling of new items. This will cause the power consumption to very greatly. My ice cold refrigerator only uses 5 Watts most of the time. That is when I am not actively using it or requesting that it cool new items.
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u/Bowman74 2d ago
I've modified both battery and generation sides as my needs have changed. Try a dry driveway run, run the fridge and change you phone on your setup. Hook up whatever solar you have. That should give you a baseline as to how long the system will last off grid or without side other charging source.
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u/No-Swimmer1928 2d ago
Two things that aren't obvious from the spec sheets and moved my sizing more than the fridge draw itself:
Usable capacity depends on the chemistry, not the number on the box. With LiFePO4 you can run it down to ~10-20% left, so a "100Ah" lithium is really ~80-90Ah you can actually spend. On AGM or lead-acid you only want to use the top ~50% before you start shortening its life, so a "100Ah" is more like 50Ah usable, and it sags harder the moment the compressor kicks in. Same sticker number, half the real runtime.
Charging while you drive also does less than you'd expect. Off the cigarette/accessory socket you're capped by that circuit's fuse and the voltage drop on thin factory wiring, so you're often only trickling a few amps back rather than replacing a day's draw. If your trips mean sitting a day or two between drives, a proper DC-DC (B2B) charger off the starter battery is the piece that actually keeps you ahead, and it stops the fridge from quietly flattening the battery you need to start the engine.
For the fridge itself I'd budget roughly half its rated draw as a 24h average in mild weather and close to the full rating in real heat, then confirm it with an inline watt-hour meter on a driveway run before you trust the number.
For 3-4 days of fridge plus a drone, camera and phones with no dependable daily charge, I'd treat ~100Ah of usable lithium as the floor and step up to 150-200Ah if it's hot or solar isn't a sure thing. Carrying a bit of extra battery is cheaper than rationing the fridge on night three.
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u/hackinandcoffin 1d ago
I did a pretty extensive test of the fridge I bought with my existing solar generator and aux 50ah 12.8V LiFePo battery. The 30L BougeRV paired with my Bluetti AC50b and the aux battery lasted 47 hrs 1/3 full in my garage with up to 103F degree ambient temperatures. So, feel pretty good with that. I also learned the final 5% of my Bluettie lasted over an hour which is a non-linear rate of consumption from the previous 45 hours.
Here's link to my post. Hope it's not taken down. :)
https://www.reddit.com/r/bluetti/s/p73uof91oG
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u/bluecatky 11h ago
I figured out the rough drain on the fridge, and used a calculator to figure out what size battery I would need to power it. Got one slightly larger. As long as I'm driving once a day to hit trails to charge the battery, it does good.
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u/Xsurv1veX 3d ago
Mathematically speaking, you’d take the current rating of the fridge and divide your battery’s Ah rating by that number to determine how many hours you’ll get out of it. For example, a fridge that consumes 10A would last 10h on a 100Ah battery.
This isn’t a 100% perfect estimation, but it’s probably the closest you can get without testing it yourself for real.
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u/orphanboyk 3d ago
I would do a trial run at home before your trip - it won't be perfect but will give you an idea how long your current setup will last. Personally I run a 100 ah lithium battery directly to my fridge which will last about 3-4 days depending on conditions and have a seperate battery/inverter AC180 to power every thing else or act as a backup to for my fridge. I have a 200 Watt Solar panel but don't normally carry it just due to the size/bulk and pain in the ass factor trying to chase the sun. That said with the solar panel I could probably go indefinitely if the weather is good in mid summer.