Practical advice about a car battery 12VDC to 110VAC inverter typical length of time to last without electricity

[trader_4]

Agree. I gave him a swag at sizing the inverter and batteries days ago, right after his first post.

[Smoke Signals]

I have a charger for my Lenovo laptop that plugs into 12 V cigarette lighter socket, so theoretically less losses than converting to AC and back to DC.

[Mark Olson]

That car charger will certainly be more efficient than plugging the laptop's mains power brick into a 12VDC to 120VAC inverter, but it is still converting the 12VDC to an AC current internally, as a necessary step in the 12V->20V DC->DC boost conversion.

[Scott Dorsey]

Yes, and such devices are also more convenient, and they are available from most laptop manufacturers or worst-case from a third party.

If you have a moderately-sized laptop pulling 50 watts and you have a car battery able to put out 40Ah or so before dying, then you have a continuous battery load of 4 amps and can run the laptop for about 10 hours.

Car batteries are starting batteries and they are designed for high peak currents rather than the ability to be discharged very far. They usually have very thin plates in order to get more plates with more surface area for the high starting current, so they are prone to issues with the plates warping when discharged a lot. So don't discharge the car battery down too far. 40Ah is not out of the question but don't treat it like a telco battery.

--scott

[Clare Snyder]

Not just theoretically.

[Clare Snyder]

It is doing it at a much higher frequency than mains voltage and it is only converting the voltage ONCE - instead of 2 or 3 times.

[micky]

That looks good.

I've bought single voltage car charger for my last two laptops. The first trip I just used the laptop a little in the car, and i'd park next to a hotel to get wifi.

But over the last 3 trips I lived in the car for a total of 4 months and I'd run the laptop off the car battery every morning to get my email and plan the day's events, and most nights, to read more email etc. It worked fine. I found the charger by searching amazon on car charger brand&model

However, it's not going to work for long unless your car is running. I woudl guesss two hours for only oone laptop, proportionally less for more t han one. I kept the car running almost all the time, partly to listen to the radio and partly because one trip it was February and March and I would be cold without the haater.

AND YOU TALK ABOUT THE CAR BEING IN THE GARAGE, WHERE THE EXHAUST GASES WILL LEAK INTO THE HOUSE AND KILL YOU. After that, the laptop will not work well.

YOu can probably park the car outside, after splicing a much longer wire into the output from the car charger. Probably a thicker wire so y ou don't have too much voltage drop.

I would work things out so you can lock the car while it's running and use a separate set of keys to open it again. Even in the safest quietest n'hood, an unlocked running car is going to look tempting to any boy 12 to 17 y.o.

BTW It is certainly wasteful to convert the car's 12volts to AC and then convert the AC to DC Waste all over the place, which means the battery dies even sooner.

[rbowman]

Stepping down can be very inefficient with a linear regulator like the LM780x family. The voltage drop across the device times the current determines the watts contributing to global warming.

The components for either a buck or boost switching converter are very similar with a slight difference in the circuit layout.

[RonTheGuy]

On Jan 07, 2023, micky wrote (in article<news: [e-mail]):

I'm not sure that needed to be shouted and I'm not sure it's even correct given that most garages are /designed/ to have cars running inside of them.

That is, most have huge vents to the outside air, and most garage doors are not airtight and all /building codes/ are different when rooms are above.

I'm not saying carbon monoxide doesn't kill but don't people who kill themselves that way usually /connect/ the tailpipe via hose into the car?

Ron, the humblest guy in town.

[Ed Pawlowski]

Never heard of a garage designed that way. Mine is hurricane proof to

150 mph wind

[Clare Snyder]

Since a laptop battery is something about65-90 watt hours capacity for a large laptop (an HP battery I just happen to have sitting here from a 17 inch Core2 is markes as 95wh 10.8 volts)) and that laptop runs over 6 hours on the battery - - that's less than 10 amp-hours.. A group 24 auto battery is good for 48-50 amp-hours - a group 27 75-95 (more or less) so if you want to limit to 50% depth of charge to be able to still start the car, you have over 12 hours of laptop use on an average car battery - with the power-hog laptop. My Acer Yoga (i7) would likely run over 24 hours in my ranger and still start the engine.

[micky]

Those cartoonist are clever, and they can draw too. I'm not either, but that's why we have them.

[Ed Pawlowski]

Thanks, I had not looked. Great colection

[Clare Snyder]

I have NEVER heard of a garage designed to have vehicles run in them and even a carport can let CO from the exhaust into a house.

[micky]

I've never heard that and all my life I've heard of people dying from cars left running in the garage.

I have never seen a huge vent to the outside, or any vent. In my experience, garages are as air-tight as they can be without spending extra money, because people go into their garage in the winter and at night, and they want to be at least moderately warm.

That's true. They can and most likely do leak around the sides, the top, sometimes the bottom, and even somewhat along each horizontal line separating segments. Despite all that, when we had an attached garage it was far warmer in it than outside. Even though the furnace had no ducts opening into the garage.

Not as far as I know, and certainly not the people who die acceidentally.

There you go.

monoxide nationwide since 2006 after a keyless-ignition vehicle was inadvertently left running in a garage. Dozens of others have been injured, some left with brain damage

This doesn't relate to you but I came across it reading about Rose Parade floats:

In parades during the late 1930s, there was a problem with drivers falling asleep along the route due to concentrations of dangerous carbon monoxide fumes from the float engines.

“The reason they always have an emergency driver on each float is because two or three fellows have been made dizzy by the carbon monoxide in the past and passed out,” said veteran float driver (and professional chauffeur) U.L. Agnameyer in 1939. Pipes carrying exhaust fumes were extended to the rear of the floats that year, reducing the threat to drivers.

[micky]

Yes, but one page I read says that modern cars also continue to run longer though the oxygen is depleted.

This is mostly about people in the car, but my point is that the car will run longer than an old car maybe would because it knows how to compensate.

"The car will continue to run on what oxygen remains in the air in the garage, but by the time that there’s not enough air ( oxygen) for combustion to continue, you’ll most likely be dead. The electronics of a modern car are designed to compensate for less than optimal conditions. It will adjust injector bandwith and timing so as to keep running. At worst ( or best, depending on how you look at it), it will just produce more carbon monoxide and Co2,, Until there’s virtually no oxygen left in the garage, or until it runs out of gas. By the time your car can’t run, you’ve been dead for a while.

People die every year from the tail pipe of the car getting plugged by snow in a snow storm, and excess exhaust gasses building up in the car. Given that a garage is a controlled environment, it’s almost impossible that you wouldn’t die from starting your car in a garage with the door closed."

[micky]

I may have been wrong when I said 2 hours. I was in a rental car and had no tools and didn't want to run the battery down using the computer and listening to the radio in the middle of a March night, then try to start it to get warm again and find the battery dead. So I was being very cautious.

[Jim Joyce]

At my house in Kansas and, later, my house in Texas, my garage doors had a pair of 8x16 vents installed into the bottom-most door panel. Some of the houses we looked at in the Florida panhandle had vented garages by way of a couple of decorative bricks that allowed air to pass through. My current home has an unvented garage.

[micky]

Wow. What's the point of the vent?

If this is a regional or climate thing btw, we never found out where the OP lives.

[Jim Joyce]

I don't know. I report, you decide.

According to Mike "Do It Right" Holmes, an attached garage should not 'leak' into the living area because the garage could have CO from a running vehicle, but I haven't seen anything that says a garage should not be vented to the outdoors. Maybe it's a safety thing.