Hello, expert solarpunk here.
TLDR: Car battery is 350Wh. Fridge uses 143W idle, so it'll run a fridge for 2-3 hours.
Explanation below:
Car batteries are lead-acid (sulphuric acid and lead plates).
They discharge according to Peukert's Law as the negatively charged plate gets covered in lead via the acid (electrolyte).
As the battery depletes, the negative plate can begin to take permanent damage, and so you can't discharge a lead-acid deeper than 10-20%, or about 10.8V, with the safe limit being ~50% discharge.
Most 12V, 60Ah batteries therefore only safely store and nominally discharge 350 Wh @ 350W.
You can discharge that as fast as you want but the faster you discharge, the lower the capacity is (with 1000-1500W bringing you way down to like 65 Wh). Fridges have a surge when they start up to fire up the compressor. Starter batteries can take that, but once the refrigerant is cold, the fridge just maintains the temperature which uses a lot less energy - about 143W on average.
142I've been living off-grid fulltime for 6 years now and that answer is completely and thoroughly wrong. Not just wrong but completely missing the fact you'll need at a minimum a 2000w inverter.
You'll get 2 hours of usage AT BEST from a car battery, and if it's lead acid, Gel or AGM chances are you will irreversibly damage (even if just slightly) the battery if you let it run until dead dead.
LifePo4 FTW!
70While reading the question I thought: "That's not how Watts work", but then this "answer" hit...
48Now I don't know enough about electronics to know how wrong this is, but I do know enough about electronics to know that this absolutely sounds wrong.
The problem comes when someone takes an answer like this, knowing far less than I do, and they try and hook up their fridge to a car battery.
And this is why I hate LLMs. Being confidently wrong is scary enough when it's just people, nevermind technology.
It does make me chuckle, though, that Skynet could have been totally innocent in their destruction of the human race, they just confidently came to the wrong conclusion and had the tools to carry it out.
Like a toddler whose inner thoughts are telling him to throw a cat out of the window. He doesn't know he's going to kill it, he just knows that's what his brain is telling him to do.
48Chat GTP answer
Sure, let's say you have a typical car battery with a capacity of 60 amp-hours (Ah).
And let's assume you have a small refrigerator that consumes about 100 watts of power when running.
To calculate how long the battery can power the refrigerator, we need to convert the power consumption from watts to amps.
Power (watts) = Voltage (volts) × Current (amps)
Assuming a car battery voltage of 12 volts:
100 watts / 12 volts = 8.33 amps
Now, we can determine the approximate runtime:
60 amp-hours / 8.33 amps ≈ 7.2 hours
So, with a fully charged 60 Ah car battery, you could run the refrigerator for approximately 7.2 hours before the battery is completely drained. However, it's important to note that factors such as battery age, temperature, and other loads on the battery can affect actual performance.
39That answer is like the electronics version of the image with Patrick Stewart and the caption:
“Use the force, Harry
-Gandalf”
37This post made me beat my head with a 2 by 4
32May be a better fit in !mildlyinfuriating@lemmy.world or similar
27I looked up the page and it gets worse.
You will need to shop for a car inverter. Find one that is at least 1,500 watts, and it will help you power your refrigerator for up to five hours—usually without damaging your car battery. Considering how much food we keep in our refrigerators, a $200 car inverter is a bargain!
23Licenced insurance agent. Not for long!
19My buddy's EV does this but without math or worrying sbout ac/dc except to pump it on the stereo that is also plugged in.
18My chickens say Shannon is full of shit.
18It hurts.
17This reads like a shitpost. The math is eh, okay, but the explanations are totally wrong. I won't even try to figure out what "runs off watts" means.
Enough of any electricity source, using various converters can get any appliance working "technically speaking", but in the end the amount of energy available at the source and the rate of consumption at the end and any intermediates. So "technically" an AA battery can power an industrial electric press, but only for a fraction of a microsecond, using a lot of charge storing infrastructure and with a lot of changes to get the tiny bit of DC into the machine requires to operate, likely 3 phase AC power.
A proper explanation would say a lead-acid car battery provides power at around 12V and electric camping fridges nominally operate around 12V so you can connect them directly and operate it (so you can sorta say they both run off DC volts?). If not you would need a buck or boost converter. The available energy of the battery (Watt-hours is a useful unit here) and the consumption rate (in Watts) of the fridge determine how long you can use it on the battery.
14classic example of being wrong with authority.
11I thought America runs on Dunkin... (doughnuts)
No easy conversation from doughnuts to volts or amps. I give up. But with enough oxygen you can hear up pretty gud with a single doughnut. Then you could use a Stirling engine to pump heat from the fridge to the environment. Energy in a doughnut ~224cal according to Wolfram alpha. That's 940kJ. 940kJ/1hr~260watts which should run a fridge for 1 hr. However energy conversion is probably going to leave you with like 10% at most of usable energy so ~6 minutes run time. America needs a lot of doughnuts!
6
2Remember the time Jeremy Clarkson fitted his car with a fridge in Africa and no one wanted to give him a jump? Yeah that.
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