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.
Isn’t that like 1250 kWh on an annual basis of idle usage? An efficient fridge should use 150-200 kWh per year, this isn’t just idle usage. Even an inefficient fridge would be really high with that kind of idle usage.
No it doesn’t. Watts do give a shit what percentage is voltage vs amps. You have to convert between AC and DC as appropriate as well as ensuring the voltage of a 12v battery is stepped if needed, but the watts are the same in any case. (Not figuring for system losses)
You should Google what a step up and step down transformer do. It’s very simple and easy to prove you’re a dipshit once you understand you’re arguing from bad faith trying to compare a simple bit of circuitry design to hydro power.
Sure, buy an inverter and burn up 10% of your energy in the conversion if you’re lucky. That inverter will cost roughly as much as the contents of a standard fridge + freezer, by the way :)
At that point just buy a well insulated cooler and always have some ice on hand. It’ll last much longer.
The question wasn’t “Is it efficient or cheap”, it was how much energy is in a battery, and if and for how long would it run a fridge. If you also want to add one more point to why you probably shouldn’t do it, car starter batteries don’t generally like to be deeply discharged, you’d want to get a marine battery for that use.
As for how much the inverter would cost, depends on the fridge, but Amazon has a 1000W inverter for around $85, that should be enough for most. Ours could run from a 300W one, they cost around $30. Pretty handy devices if you want to run any kinds of electronics from a car anyway, I have one for when I want to charge my laptop and RC batteries on the field.
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.
Isn’t that like 1250 kWh on an annual basis of idle usage? An efficient fridge should use 150-200 kWh per year, this isn’t just idle usage. Even an inefficient fridge would be really high with that kind of idle usage.
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No it doesn’t. Watts do give a shit what percentage is voltage vs amps. You have to convert between AC and DC as appropriate as well as ensuring the voltage of a 12v battery is stepped if needed, but the watts are the same in any case. (Not figuring for system losses)
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You should Google what a step up and step down transformer do. It’s very simple and easy to prove you’re a dipshit once you understand you’re arguing from bad faith trying to compare a simple bit of circuitry design to hydro power.
deleted by creator
Removed by mod
https://youtu.be/GtTcuexjeRw?si=e1p0nUHh1uXBp24R
3 seconds of googling like I said
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https://piped.video/GtTcuexjeRw?si=e1p0nUHh1uXBp24R
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Watt hours are watt hours. Sure the compressor won’t run on 12 volts as is but the energy is there, just needs a converter.
Fwiw, our 15 year old fridge uses around 1000Wh per day.
Sure, buy an inverter and burn up 10% of your energy in the conversion if you’re lucky. That inverter will cost roughly as much as the contents of a standard fridge + freezer, by the way :)
At that point just buy a well insulated cooler and always have some ice on hand. It’ll last much longer.
The question wasn’t “Is it efficient or cheap”, it was how much energy is in a battery, and if and for how long would it run a fridge. If you also want to add one more point to why you probably shouldn’t do it, car starter batteries don’t generally like to be deeply discharged, you’d want to get a marine battery for that use.
As for how much the inverter would cost, depends on the fridge, but Amazon has a 1000W inverter for around $85, that should be enough for most. Ours could run from a 300W one, they cost around $30. Pretty handy devices if you want to run any kinds of electronics from a car anyway, I have one for when I want to charge my laptop and RC batteries on the field.
Energy is energy, you are not an electrical engineer.
Congratulations, this is the worst attempt at ridicule I’ve ever seen
You have a very inefficient fridge! My fridge is rated for 272 kWh per annum, which is 745 Wh per day or 24 Wh per hour. You need to buy a new fridge.