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classic example of being wrong with authority.
Safety is no 1 priority!
He looks shocked.
Mehby
May be a better fit in !mildlyinfuriating@lemmy.world or similar
For the uneducated, what’s wrong with it?
If a wire were a water stream:
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Volt is water pressure (fast or slow stream)
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Ampere how much water there is in the stream
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Watt is pressure x amount
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Ohm (resistance) is how much obstructions are in the stream
I never got the pipe analogy. Since liquid water can’t be compressed, wouldn’t the amperes be directly proportional to the volts and to the size of the pipe, assuming there are no air bubbles? Also, supposedly resistance only reduces current, but when I think of hair in a pipe, the pressure after the obstruction would also be lower (because pressure is directly proportional to the amount of water that flows)
Since liquid water can’t be compressed
Common misconception - it can, just not very much, so the volume change is tiny, and in practice, there’s usually something else in the system that is changing volume by a larger amount- like air bubbles, or if there’s anything elastic in the plumbing, it will stretch - but regardless, water absolutely can be under pressure.
resistance only reduces current, but when I think of hair in a pipe, the pressure after the obstruction would also be lower
You are correct, in electronics, resistance drops voltage (assuming the load is in series with the resistance). In fact, a cheap quick and dirty digital to analog converter uses a bunch of resistors to supply different voltages…
https://www.youtube.com/watch?v=X_crwFuPht4
AlphaPhoenix also has other fantastic videos explaining and experimenting with all sorts of interesting things.
Resistance in wire creates a voltage drop, just like hair in a water pipe creates a drop in available pressure.
He expressed it wrong. Amperes is diameter of the pipe, how much volume (or charge) can be transferred per unit of length at a given pressure; Watt is the amount of water flowing out at the end, which depends both on pressure and diameter.
Watt is the amount of water flowing out at the end
Shouldn’t it instead be the sum of the kinetic energy of all water molecules that come out the other end per unit of time (ie. total amount of energy you use move your volume of water with a certain pressure in a second)?
What a straightforward and clear way to put it, thank you kindly!
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It’s being answered authoritatively by an insurance agent.
I mean, the running on watts vs volts part was nonsense.
But, did get quite close with the power calculation. Although here in the UK the average car battery seems to be around 60ah. I did see some very expensive large 105ah batteries. But they were definitely the outlier. So if you had a 100ah battery then it would be 1.2kwh with 100% efficiency.
Also, it doesn’t mention that you’d need an inverter to make the fridge run from a battery. These also have inefficiencies which would reduce the runtime on the battery.
A little more technical, I don’t think your average starting battery is 100ah capacity, and most don’t rate themselves in amp hours either.
I bought a deep cycle for my little sailboat at the local auto store and it’s around 70-80ah
You would need an inverter to convert the batteries DC (direct current) into AC (alternating current). This will “cost” some power (watts) to convert that voltage. Your refrigerator runs on AC battery outputs DC.
That said, it is quite common to run refrigerators on larger boats and RVs off batteries and it would certainly be possible to run your house fridge off a single car battery for a short while if you’ve got an inverter large enough to run it.
What your not gonna do is just run out to the car, grab your battery and hook it directly to your fridge.
Our fridge uses between 130-180 watts when running and about 2.9Kw or 2900 watts in 24 hours. Your battery most likely has under 1000 total watts til empty, and car batteries are generally not used past 50% capacity (lead acid starting battery). So figure 500 watts max (for easy math). So… 4h run time maybe.
While it’s true that it won’t be at max capacity, I will say that batteries these days will rate themselves in amp hours. For instance usually an 800 CCA AGM battery lists itself online as 7.5 AH.
The conversion process involves using the formula CCA = 7.2 x Ah to convert from Ah to CCA, and Ah = CCA / 7.2 to convert from CCA to Ah.
I specifically looked at the available specs at the local auto parts stores and couldn’t find Ah details. This was about 2y ago, so maybe this value is becoming more commonplace. I know in the RV/Sailing works Ah is used pretty exclusively. My deep cycle AGM only lists CCA and reserve capacity
In your last paragraph, most of the places you write watts you mean watt hours. Good reminder that Wh is a bad unit, since it’s too easy to confuse with watts.
Good catch… It was early and I was on my phone (my excuses) :)
It’s just the 2.9kw should be kWh. Everything else is close enough.
Watt and volt are two different measures for electricity. Also your fridge will not work when hooked up to a car battery for many other technical reasons, including differ t voltages, and current types (AC/CD, not the band)
Unless you have an EV with V2L.
Sure you can use the 12v battery and convert that power but you can’t just connect a 12v battery and expect it to work.
You stated that you cant connect a car battery to a fridge. You said nothing in your comment about 12v. I can connect my car battery to my fridge no problem.
You can but it won’t keep your fridge cold. (Unless you use an inverter and you would need to check the amps needed by the fridge when the pump is on and see if your battery and inverter can provide that.)
As i stated I have V2L on my car. I also have normal outlets inside the car.
That’s wrong. Watt is a measure of power and volt measures…… voltage.
Charge (electricity) is measured in Coloumbs (sp?)
You need a complete circuit for Watts as P=iv.
I is current, measured in amperes
With the river analogy, Voltage = pressure, Wattage = how much water is passing, Current (Amps) is how wide the river is.
Pressure * Width of river = Amount of water passing
Not sure that helps with passing it through the terms and then to variables.
Water analogy works better with plumbing. A river, not so much. But people aren’t that much better at understanding plumbing, unfortunately…
Volts measure voltage?
Tautologists study tautology tautologically.
The first rule of tautology club is the first rule of tautology club.
The first rule of tautology club is the first rule of tautology club.
Electrical potential, IIRC
Another way to think of it is this: Volts are like water pressure (potential energy) Amperage is like the flow rate of water Ohms (resistance) is like how hard it is to push water from high pressure to low pressure Watts are like the volume of water (a unit of energy)
A big hose has low resistance, water can move freely A coffee straw has large resistance, it’s hard to pull and push water thru it
A river has very low water pressure, and the speed of the water can vary, so volume of water moving can be huge so the flow rate of water can be huge as well. A pressure washer might have very high pressure, but use as much water as a kitchen faucet. Certain applications need high pressure, some need low pressure. A car battery is like a river, low pressure (typically 12volts) but move a lot of amps (cold cranking amps of up to 500-600 ish usually), and a wall outlet by comparison is like a pressure washer with 120v, 15A (in the US). A fridge won’t play nice on 12v, it needs 120v. It might need 400 watts which a car battery can do but it cares about how it can get that by requiring higher potential.
A watt, W=VA, can be thought of as asking how much water is there? 1 minute under a sink verse 1 minute in front a fire hose has two very very different amounts of water.
A watt hour, which most people are familiar with in the US for billing on their utilities, is like asking how many cups of water an hour. A light bulb needs a fraction of a kilowatt hour, a drier needs multiple kilowatt hours, but might only run for 30 minutes.
This idea gets a little tricky and falls apart at its edges but as a general idea should hold up for most peoples understanding of electrical stuff unless you work with it daily like an electrical engineer, electrician or something similar. For sanity sake I’m not going to try to apply this to AC verse DC, I don’t have a good analogy for that
Obligatory mobile formatting heads-up and what not and I’m not caffeinated so meh
Ugh, you’re getting into the realm in which technicality is hard to explain.
That’s technically wrong. Even though ampere is coulomb/sec, electrons don’t actually flow.
Like I said it falls apart on its edges but for most people it’s probably a better understanding of it than they will ever have or need, but most people scrolling thru Lemmy probably don’t need to be understanding electrical concepts like electrons not actually flowing, charge, etc. I’m a controls engineer and while I am aware of the concepts and such, I am not designing electronics so at the end of the day I barely have a use for half of the concepts myself. Sure I could get down to the half semester class of quantum where things get weird, but that won’t easily tell people to not to try to plug their fridge into a car battery
For the AC/DC part, I usually try to tell people it’s like a water wheel that’s been inserted into the hose of water. DC is it spinning one way constantly, while AC is it spinning back and forth. The wheel is turning pretty much the whole time (again, we can try to not be super specific with the way we do phases with AC), and thus you can use it to do stuff on AC or DC.
Clever, it just breaks down again with my analog of water volume lol. Definitely not saying it’s wrong, I just like to leave it off so there are less questions haha
Unless you have an electric car that can do vehicle to load. That means that you can plug in regular household devices like your fridge.
That vehicle isn’t using a traditional 12v car battery for that. Also the point t is you can’t connect a car battery to a fridge and expect it to work.
Not with that attitude!
You’d need an inverter in-between, yes.
But for the record, inverters have been in gas cars with plain old 12V batteries for years. But you’ll need the engine running.
Yes. That not the “use a12v battery” assignment. It would be use an inverter…
The only way the “uncle” is correct and the only way a 12VDC battery is getting connected to a regular, 120VAC refrigerator, yes. And what most inverters run off of.
So. The answer is yes you can. If the car is an EV with V2L. Which I am guessing is what that uncle was talking about in the post.
V2L doesn’t relies on traditional 12v battery…
Okay. But it’s a car. Full of batteries.
Correct, but entirely besides the point.
One running on “Volts” and another running on “Watts” is like refusing to compare two cars because one car runs on Wheels and the other running on Motors
Well, you just have to convert wheels to motors. A car runs on wheels, which is 1/4 motors. A boat runs on motors, and has one, meaning it has 4 wheels and is probably street legal!
Almost every sentence. But funny self review and other things aside, main problems:
“Watts… Contains.” Is a fundamental confusion on what a watt is. It’s like asking how much fast there is in a box.
The answer has a good basic idea, but also a total comprehension failure not just pulling the numbers out of thin air, but badly describing an equation with watts on one side and watt hours on another. The answer is both ignoring realities and getting the hypotheticals wrong. Sounds expertish but is both wrong and useless.
When they could have just said “yes, you could use a suitable inverter with a suitable battery and a fridge in some cases, but the math and actual connections would be more complicated than that explanation” or something like that.
Uh, watt?
Volt
Jiggawatt
Whaddid u call me
OHMybad
uwattm8
Jigga deez nuts!
We know this comment by Shannon Martin is correct and sensible because it was reviewed by Shannon Martin! As a licensed insurance agent, I’m sure she is qualified to talk about uh… electronics… hmm
worst ai prompt
This is the sort of person who thinks you need to ground yourself to be safe while working with electricity. Not 100% wrong, but just wrong enough to be very, very dangerous.
Working with small ESD-sensitive electronics and using a proper grounding strap and mat with large resistors in series to provide protection from shock? Absolutely.
Wiring up a car battery or working with mains power? Absolutely not.
Car battery on its own won’t kill you, though wiring many in series might. There can also be some effects from DC sparks and welding on even 12V, which might cause other problems.
Just ground your left hand while you work on it with your right hand. That way if it’s live it’ll quickly stop your heart and you won’t even know you died. No half measures!
Some people know just enough to be dangerous.
For instance, an anecdote:
A nearby local hardware store put up a sign in 2017 and now this year, in front of the welding equipment, that says “WELDING GOGGLES DO NOT PROTECT EYES AGAINST THE SUN”
Now if they didn’t block uv from the sun, then they wouldn’t block uv from your welding arc.
BUT I 100% stand by their choice to put the sign up.
Because you need a certain shade or darker, and they sell a lot of different shades for different welding applications, including the safety tints people might want if they’re nearby and catch the occasional reflection.
And some people know enough to know welding arc = UV, sun = uv, and don’t stop to think about intensity.
In fact, in 2017, I knew someone who tried to use a #3 lense to look at the total eclipse, and as soon as the moon cleared moved enough for the sun to peek back, he deeply regretted not using a darker shade. Now has a weird spot in his vision that isn’t quite right.
A 3 is what my helmet gives me for grinding mode, that’s nothing.
I used a 10 or 11 for one eclipse and it worked alright.
Licensed Insurance Agent
Chat 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.
3.5 or GPT-4? I can run the latter if need be.
if the car was running, the alternator would be charging the battery. would it be able to keep up with the drain of the fridge of just extend the time a bit?
Probably depends on the car + alternator, but it’s not so rare for modern gas cars to have AC outlets for backseat passengers, and the ones I’ve seen are typically rated 120-150W or so. Glancing at the power meter I have on my fridge, it uses ~110W while running and only runs ~10% of the time.
Theoretically the car probably can keep up while running, BUT
Compressor startup current may blow whatever fuse is protecting that circuit.
AND
Cars are very inefficient generators. You’d be wasting a bunch of fuel so I wouldn’t generally recommend it unless it’s an emergency.
That said, in an emergency it may be worth doing for like 20 min on / 1 hr off, so that you’re running the engine only when needed, but I’m not an expert, that’s just pure speculation.
Please tell this to my dead car battery. It was killed by the tiny dome light last night, because I forgot to turn it off.
If your dome light isn’t an LED, then you should replace it with one. It won’t completely fix your problem but it will give you 9 to 10 times longer to catch it.
There’s really no reason that every car doesn’t have a voltage cut off to protect the battery such that it can still start. Additionally, if they just included a super capacitor then even with a heavily discharged battery, it could charge up the super capacitor to then start the car.
But if we went around doing smart stuff like that then we could potentially wreck the entire lead acid battery industry and that would just be awful…
I’d have expected ChatGPT to be able to call out power factor as well. Otherwise you’re getting volt-amps, not true wattage
Power factor isn’t a thing in DC and GPT appears to have assumed a DC powered fridge.
And losses in the inverter.
Given the lack of an inverter in GPT’s transcript there’s no AC to invert.
I’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!
I’ve also done the off grid thing and you can get way more than 2 hours on a car battery if the fridge is already cold and you aren’t constantly opening the door. Also have ran modem full sized fridges on 1000w inverters. So YMMV.
An inverter will not let you run your fridge until the battery is “dead”. It’s going to have a low voltage cut off, likely somewhere around 11 Volts, specifically to avoid damaging batteries by fully discharging them.
How many hours you’ll get from the battery mostly depends on your ambient air temperature and how often you open the fridge. They don’t use that much power when they’re idle - my fridge averages at about 90 watts (I’m not running off grid, but I do have rooftop solar and our system produces pretty charts showing consumption). A large car battery can sustain 90 watts for a quite long time - well over 2 hours. Probably closer to 10.
Running a fridge off a car battery long term is a bad idea. But in an emergency? Sure I’d totally do that - especially if your “emergency” is genuine such as needing to keep your medication cold. Just don’t open the fridge unless you’re taking your medication.
LifePo4 FTW!
Sure. Way better than lead acid. But that doesn’t mean lead acid is useless. When I lived off grid, LifePo4 didn’t exist and we got close ten years (of daily use) out of our lead acid batteries. They were bigger than car batteries and also deep cycle ones, but in an emergency a car battery would be a fine choice if it’s the best one you have.
Easy big fella. I over generalized and I’ve been on the internet long enough to know that a fully contextualize and source siting answer is always called for. Also you’re explaining this to a guy who lives off of 400ah on a 29ft sailboat and hasn’t been to a dock or a slip in 5 years. I get it.
I’ll need a source for that claim buddy
Actually when I lived off grid for 80 years, we used 7 AAA batteries on a rotation and recharged them by rubbing them on our wool sweaters, so those guys are totally right.
Wait, so you are saying you have either lived continuously on a 29ft boat for 5 years, or only have visited land by dinghy or something while its anchored?
Wild. That’s got to be a nasty looking hull though.
So if I turn the car battery upside down, a 12v DC battery should run a 120v AC appliance?? Brilliant! I have an idea for how we can use this with two fans to create infinite energy!
It will never beat my idea to strap a buttered piece of toast to a cat and make antigravity.
A car battery shouldn’t be discharged at all. They are meant to supply a short burst of power and then be charged back up again.
A deep cycle lead acid battery can be used to run an inverter. They can be discharged to 50% capacity while still providing hundreds of cycles. If they are used for a backup and are not cycled frequently, they can be discharged to around 80%, but they will provide a lot less cycles.
A LiFePO4 battery is definitely the better choice for anything that needs to be cycled frequently though.
Sure but in an emergency? They can handle being discharged as long as you don’t go too far.
Just wire the inverter to your car battery and run the engine. Hard on gas compared to a 3500 watt generator, but you already have the car, inverters a few hundred bucks, and the genny would be at least 2500 dollars
An alternator can’t output full power when the engine is idling. You may only get a few hundred watts before the battery starts draining. You can get a generator that will produce much more power than a typical car alternator for under $400.
I run a fridge freezer off a Delta Pro and 600w of solar during the summer. If we get a few days spell of bad weather I have to place it back on mains. Its good to have in an emergency, though it cost me 3 months wages (plus overtime)
Licenced insurance agent. Not for long!
Remember the time Jeremy Clarkson fitted his car with a fridge in Africa and no one wanted to give him a jump? Yeah that.
My jeep has 3-prong electrical outlets. Not sure how much it will power and i assume you would want to have the car running.
From the owners manual: “There is a 115 Volt, 150 Watt inverter outlet located on the back of the center console to convert DC current to AC current. This outlet can power cellular phones, electronics and other low power devices requiring power up to 150 Watts.”
I don’t know if I’d plug in a fridge to that. I was wondering because my father in law’s truck has a similar outlet and I know he’s blown a fuse using it to power power tools.
I measured my fridge. You could, in theory. Problem is that the motor in the fridge (and in power tools) is an “induction load”, meaning it draws a lot more power in a split second when starting. Inverters have to be built with that in mind, or just stronger (killowats range).
After the freeze in Texas a couple years ago, when many people lost electricity, Ford started advertising the outlets on their trucks.
Edit to add the link - https://www.ford.com/trucks/f150/f150-lightning/features/intelligent-backup-power/
My father in law drives a 2015 F150. That outlet on the center console is 120 Volt outlet supplies 400watts. But a fridge can be anything from 300 to almost 800. I’m not saying it’s impossible. And with newer trucks (especially the lightning and the F150 hybrid), I would believe it more readily. Ford is quick to market this in new trucks but I wouldn’t count on it with older trucks. I’m just pointing out that real work experience says your mileage may vary. Especially in places like Texas or Arizona where your battery is going through extreme heat cycles due to the weather from like February to November.
I wanted to say “look at the label but it should be fine” but then I did a quick google double-check and depending on whether you get US or EU results you get quite different answers: US 350 to 780W, EU 100 to 300W. Refrigerators have quite lower numbers but we wanted a fridge so let’s look at small refrigerators with proper fridge compartment (four stars, -18C), like… a Beko TSE1284N b100, 240 bucks not fancy not shoddy (Beko in a nutshell, honestly). Damn, why are they only listing kWh/24h and kWh/a. Whelp. No pictures of rating plates anywhere. Oh. According to Amazon “50W”, according to another trader 90W connected load, which makes sense if we understand those 50W as consumption load (or whatever those things are called in English).
So, yeah, look at the label and you should be fine. Don’t get that fridge though it’s 220V.
Just make sure you open the garage first
Looking passed the absolutely insane answer here, no one has even brought up the whole issue of AC vs DC. Batteries are DC, while your fridge that plugs into your wall running on AC. I know they make DC ones, but it isn’t like they are interchangeable.
That part just takes an inverter.
I’m not sure of the max load output on a car battery, but with a 15 amp 1800 watt dc to ac inverter, you probably can run a fridge off one. It probably just won’t last all that long.
Just run the rectifier in reverse, duh
There are DC-AC converters you can use (might be called inverters in English idk), which are pretty interesting circuits. They are used all the time, e.g. to use solar energy
Shannon Martin says just shake the battery and you’ll get DC.
Just swap the leads back and forth very fast
Funny thing, most modern refrigerators use DC motors for their compressors so that they can run at variable speeds, so there’s likely an inverter that you could bypass if you know the appropriate voltage. The DC ones for RVs are the same internals, just without the inverter.
Funny thing, most modern refrigerators use DC motors for their compressors so that they can run at variable speeds
No they don’t…they use AC motors and a VFD to control the speed.
I mean it’s probably labeled, right? How hard could it be?
Exactly. Find a hole that’s black and a hole that’s red, and stick some wires in there. How hard could it be?
(can’t answer, because she was fucking electrocuted)
Correction: they still use AC motors, but those motors don’t use line AC. It goes line AC > rectifier > DC > inverter board > variable frequency AC to run the compressor motor.
Most RV fridges just use DC motors, but there are some that use VFDs and AC motors.
It hurts.
This reads just like an AI response
AI told me 75C/170F is ideal for hot tub water temperature.
Sure no problem. Once I get used to that I’ll work my way up to boiling peanut oil.
75°C is definitely ok for a hot tube for a short session.
Sure but you can only do it once!
Seriously, even 75C water coming out of the tap would be dangerous and negligent.
It’s usually 96 if you have a boiler. No issues.
So who is your skin graft guy?
But only if you have purple eyes
I spilled a half cup of 175F water on my hand and got blisters. You absolutely cannot bathe in it.
Forget 75°, just 65°C (150°F) will give you third degree burns in 2 seconds:
Most adults will suffer third-degree burns if exposed to 150 degree water for two seconds. Burns will also occur with a six-second exposure to 140 degree water or with a thirty second exposure to 130 degree water. Even if the temperature is 120 degrees, a five minute exposure could result in third-degree burns.
(°F)
Most adults? What happens to the others?
They will instantly explode into pure energy
Tobe honest three degrees burn doesn’t sound bad. I’m looking at my protractor and as long as you aren’t far away from the tub three degrees should burn that much
I guess I’m long dead, lol.
Just brain dead 😅
Temperatures beyond 50°C are an acute risk. 75°C can cause lasting damages.
Yeah but you are talking about hot tubs and they are talking about hot tubes so maybe the rules are different like the tube is really hot but is a poor thermal conductor. Or they misspelled tub and they really like burning themselves… lots of options for interpretation here.
“Hot tube” seems like a slang for some kind of drug device. Like a weird bong or something
It could also be a gross sex term for a dick. During sexy time someone could say to me “yeah give me that hot tube” and I would be immediately less interested in sex.
Sounds like something that you would find in a bargain-bin romance novel.
“His hot tube pulsated, throbbing with motion” or something like that.
Ever been to sauna? Especially the Russian one? There’s no risk if you don’t have heart issues.
I’m regularly going to a Finnish sauna with >80°C, but air with 100% humidity is not the same as immersing yourself in scalding hot water.
The Finnish sauna is dry. Russian and Turkish are wet with high humidity.
In mother Russia, Sauna evaporates you
A sauna is not immersing your whole body into the water.
Ever been to Russian sauna?
If nothing else, the tub would certainly be hot at that temperature.
At what temperature does it cease to be a bath and instead become human soup?
It is at this point that the reader questions their own existence.
In the tub. For a relatively short time.
