12 volt car heater/defroster that works?

It depends on your needs, which mostly depends on where you live.

Depending on the cars electrical system I'd say you can't reliably pull more than 200 watts for any length of time, and that is while cruising.

200 watts isn't going to produce a lot of heat.

A hair dryer is around 1000 watts or so, which is five times as much, and that too may be low depending on climate.

Well, the current is the problem. The ones I've seen are around 300 watts, which at 12v is 25 amps. You can't really draw much more than that without a wire direct to the battery, but then you have another problem. I don't know how big your alternator is, but 60 amps would be a good wild guess, and it has to run everything else too. So if you try to draw 50 amps for a couple of those little heaters, you're going to have a problem. (I don't know where you live, but you'd need more than two of them around here.)

You could fix it yourself. Heater cores are cheap. It's expensive to pay someone to do it because in some cars it's a real pain and takes a long time. Buy a Haynes or Chilton's manual first.

Or, if the leak is small, you could try some radiator stop leak. I've found Alumaseal and Bars Leaks to work best.

-Dan

I don't know about car electric heaters from experience, but the current draw and energy expenditure for one to actually be effective would be very high. It would likely need a transformer and hard wiring.

I really responded to ask what year Escort. If this is an old Escort up to about 1990, the heater core is very easy to replace. You would be wise to do it yourself. Even if it took a weekend, the time would be well spent. The core is available at chain stores for about $40. If you have a newer Ford/Mazda Escort, then I think that the evaporator has to be moved and the A/C system discharged to get to the heater core. This would be beyond a DIYer's ability, mainly due to opening the A/C system.

I have done the older style and it is a piece of cake.

Toyota MDT in MO

No. Think about it. If you have a 20 amp circuit at 12V, you can draw 240 watts. That's not very much heat. Compare with a couple kilowatts from a conventional heater.

Replacing the heater core on an Escort isn't actually very bad if you don't care what the dashboard looks like afterward. You can cut into it with a saw and get to the core without too much fuss. Most of that $700 is involved in taking the thing apart and putting it together so it doesn't look like shit. But if you don't mind it looking like shit, you should be able to do it for a lot less.

--scott

The old Escorts are pretty easy to fix. You should be able to get a new copper core for less than $50. If this is just a work car I would be tempted to stick a core on the air vent, either inside the car or on the air intake. Or just lay it on the floor with a little 12v fan blowing on it.

Transforming DC? Nice trick.

My thought, as well.

Also could wire in a second battery, just for 12 V heater(s). When it's low, flip a switch to let the alternator charge it, or have a sep. charger at home. They also make 12 V electric blankets, which can help quite a bit. Esp. if the Wife puts you out. :)

I'd think twice about such a set up... no doubt it would work, but say you were in an accident, or the core or hoses were damaged for any reason, you and/or your passengers could be seriously scalded.

Also, even a small hole punched in the core by whatever rolling around on the floor would very quickly fog up the windows... the colder out out the faster.

Erik

Haha, I love the blanket thingie if thrown out by wife or girl friend in my case...will get one and put it in the back for the winter. Well, I have asked around, the install of the heater core is a b......, from what I've been told. I can see where it would be difficult to put everything back after you took it off, like instrument panel-wise, esp. from my olden days of working on my bike, no, not cycle, the pedalling kind, hehe!

I th>

No, this Escort is a 1995. You know we had the car inspected and the oil changed the day before but probably just a coincidence as it was hot when it happened. The car is getting old, like all vehicles they tend to begin unraveling. I have never had a heater core go on me before though.

The engineers who designed it this way, denying easy access. Well, they should make them change one heater core, that would bring them back to the drawing boards. Why don't designers ask the regular driver and owner what they want and need in their vehicles, easier access to me, would be a given. Again, thanx for the assistance, psongman

DC to DC, y'know, with a rectifier. Would a transformer *not* be used?

I thought so.

Toyota MDT in MO

AC to dc uses a transformer/rectifier, at least in the old days. :) Now it seems they can dispense with the transformer, judging from how lite battery chargers are these days--solid-state magic? DC to AC uses a solid state inverter. In the old days, a mechanical inverter. DC to dc proly uses some combination. Wasn't even possible, practically speaking, until relatively recently.

Yeah, I felt a response coming when I typed transformer instead of inverter, but it seemed adequate at the time given the OP doesn't know

*why* a 12V heater won't work well. Anyway, the commercially available ones I am aware of that would pass high amperage at 120 volts AC are still big and heavy. They appear to be conventional DC to DC converters with a transformer. Many smaller ones have appeared, but with very low wattage limitations from what I've seen.

Toyota MDT in MO

In article ,

They still do.

What they do is rectify the AC, then use a solid-state inverter running at a very high frequency. The high frequency means the transformer is very tiny and very inexpensive.

Yes.

Back in the old days, you'd either do it with motor-generator sets or with a mechanical inverter driving a transformer driving a rectifier stack (as seen in most old car radios to get the high voltage for the tube plates.)

The economics are totally different than they were when I was a kid. Used to be transformers were cheap and switching electronics were expensive. Now switching electronics are cheap and transformers are expensive.

--scott

Also, of course, the problem is getting power out of the battery. Cranking the voltage up with an inverter doesn't help you do that. If you want

1200 watts, you either need to get 100 amps at 12V, or 10 amps at 120V... and if you use an inverter to get those 10 amps at 120V it will require at least 100 amps at 12V into it.

There is no free lunch. You do not get power for free, and sadly it takes a whole lot of power to make heat. This makes you really appreciate just how good the power density of gasoline really is. You get a whole lot of heat out of a little gasoline.

--scott

Certainly more if you factor inefficiency losses in the process.

Not to mention *free* heat, as the various powerplants in use today don't use their generated heat very effectively. Shed heat might as well go to some *good* use like cabin heating, besides just soaking into the condenser and atmosphere.

Toyota MDT in MO

Yes, but the GOOD news is that all the losses come out as heat, which is what you want in the end anyway.

Precisely! If only VW could have figured out how to deliver it properly....

--scott

It works as well as it can be made to work, given the technical limitations, which I and a couple others have explained to you.

Let me simplify my original answer a bit further:

Short answer: It's not possible to get more than a fraction of the necessary heat from 12v in a car.

Slightly longer answer: Anything's possible, but it would cost a lot more than you want to spend, and you're a long way from the knowledge necessary to do it yourself without really messing up your car. It's way past the impractical point, even for someone knowledgable enough to do it.

-Dan

new to this but where are you from? 700 is crazy. i work as a mechanic and thats a rip off.