How many hours, will this specific battery charge this specific fridge?
- Thread starter Joe98
- Start date
Thank you! I had missed that point! I will look out for it with other batteries!
Given this is a 70Ah battery, I was expecting: "Joe, you will get 70Ah in a laboratory, but in the real world you have to open the fridge so you might get 50 hours".
I am aiming for 48 hours. That is 9:00 am Monday to 9:00 am Wednesday. On Tuesday the battery could be topped up with solar which I hope means extending the power to 9:00 am Thursday..
???
Ah is a unit of energy storage.
Only tenuously related to the hours of use you get.
But I think you got the message anyway
"It depends"
4000lbsOfGoat
Well-known member
I rarely run a full 48 hours without recharging but I have done it just to make sure that I can in a pinch. I run a few more items than you are talking about (specifically a cpap overnight, which is a bit of a draw, but very little compared to a fridge). In reasonable temperatures (70s F) I use around 1.2 kWh hours over a 2 day period - most of that being the fridge.
If you want to reliably run for 48 hours without recharging then I think you'll need *at least* 1kWh of capacity (83 AH at 12v nominal) - and that will be under ideal conditions.
Martinjmpr
Wiffleball Batter
Here's a data point, for what it's worth (not much, I think):
Back in September of 2019 I had just gotten my F-150 and hadn't made any mods to it. We had a camping trip at the rural home of a local car collector (Rambler Ranch, for those who know or who have been there - the most amazing collection of cars I've ever seen in the hands of a private owner!) We were camping in an open field with NO amenities of any kind (no electric, water, etc.)
I was in the early stages of putting together my 12v "Power box" which consisted of a 90AH group 27 FLA (Wet) battery in a trolling motor box. This in turn was used to power my fridge, a well-used Indel-B TB-41 (41 liter) compressor fridge. We typically keep the temp control on this fridge around 30 - 32f degrees (0 to -1c) (because the temp sensor is on the bottom of the fridge, i.e. the coldest part, setting the temp at 32 ensures that the entire fridge stays below 40 [5c] , which is needed to keep food from spoiling.)
It was mid September and the days were warm, getting up to around 80 degrees.
At the time I had no way of recharging the power box while traveling (I later installed a 20a DC-DC charger in the truck.)
We arrived late afternoon on Friday and by the end of the day Saturday, 24 hours later, the voltage was down to about 12.1 which is about 50% discharged according to the data I've seen. At that time I connected a 100w solar panel to it and was able to get it charged back up to about 12.5v with 3 - 4 hours of good sunlight. We were parked in direct sunlight with no shade, and as I said it was warm.
So, in my case, at least, with my fridge and under the circumstances in which I was camping, my 90ah battery would have given me, at most, maybe 36 hours before dropping to levels low enough to trigger the low voltage cutoff on the fridge and/or possibly damage the battery.
Since that time, I've not only installed the DC-DC charger, I've also gotten better about making sure the battery stays charged up with the solar panel if neccessary.
Most of the time we camp we are in the truck and driving almost every day which gives the DC-DC charger plenty of opportunity to charge up the power box. If we're sitting in one place for a very long time with no electric power, and the trailer battery is fully charged (the 100w solar panel does a very good job of keeping our 2 x 6v FLA golf cart batteries fully charged) I will sometimes connect the solar panel to the power box just to keep it topped off.
TL;DR: IMO 70ah is marginal if you want to run a fridge for 48 hours without recharging. I would want 100ah or even more if possible for running that long. Otherwise consider a 100W solar panel kit to keep it charged up.
Back in September of 2019 I had just gotten my F-150 and hadn't made any mods to it. We had a camping trip at the rural home of a local car collector (Rambler Ranch, for those who know or who have been there - the most amazing collection of cars I've ever seen in the hands of a private owner!) We were camping in an open field with NO amenities of any kind (no electric, water, etc.)
I was in the early stages of putting together my 12v "Power box" which consisted of a 90AH group 27 FLA (Wet) battery in a trolling motor box. This in turn was used to power my fridge, a well-used Indel-B TB-41 (41 liter) compressor fridge. We typically keep the temp control on this fridge around 30 - 32f degrees (0 to -1c) (because the temp sensor is on the bottom of the fridge, i.e. the coldest part, setting the temp at 32 ensures that the entire fridge stays below 40 [5c] , which is needed to keep food from spoiling.)
It was mid September and the days were warm, getting up to around 80 degrees.
At the time I had no way of recharging the power box while traveling (I later installed a 20a DC-DC charger in the truck.)
We arrived late afternoon on Friday and by the end of the day Saturday, 24 hours later, the voltage was down to about 12.1 which is about 50% discharged according to the data I've seen. At that time I connected a 100w solar panel to it and was able to get it charged back up to about 12.5v with 3 - 4 hours of good sunlight. We were parked in direct sunlight with no shade, and as I said it was warm.
So, in my case, at least, with my fridge and under the circumstances in which I was camping, my 90ah battery would have given me, at most, maybe 36 hours before dropping to levels low enough to trigger the low voltage cutoff on the fridge and/or possibly damage the battery.
Since that time, I've not only installed the DC-DC charger, I've also gotten better about making sure the battery stays charged up with the solar panel if neccessary.
Most of the time we camp we are in the truck and driving almost every day which gives the DC-DC charger plenty of opportunity to charge up the power box. If we're sitting in one place for a very long time with no electric power, and the trailer battery is fully charged (the 100w solar panel does a very good job of keeping our 2 x 6v FLA golf cart batteries fully charged) I will sometimes connect the solar panel to the power box just to keep it topped off.
TL;DR: IMO 70ah is marginal if you want to run a fridge for 48 hours without recharging. I would want 100ah or even more if possible for running that long. Otherwise consider a 100W solar panel kit to keep it charged up.
broncobowsher
Adventurer
Add to that batteries are rated for full discharge, which isn't good for them. If you do a decent job of limiting the depth of discharge the life will increase almost exponentially (there are limits still). You are probably looking at a lot closer to 150 Ah of battery to handle that 83Ah of potential load.
But I thought I saw solar mentioned being added to the mix. That does wonders. Providing you get some sun. I have about 400W of panel, but if shady I might only get 40W out of them. But that 40W is enough to run the fridge without eating out of the battery. And little bits of sun, and when the fridge is cycled off, that goes back into the battery. I have other power plans, that would be completely overkill just for a fridge. My first rig was running a fridge off a 70W panel and the starting battery (don't recommend the starting battery idea) and I have run it for 36 hours and could still drive home in the afternoon. A 100W panel and a 100Ah of battery should do a nice job. Especailly if you add in vehicle charging as you drive.