Amateur questions - how to reduce DC amps ? Auto shut off?

A simple way:

It won't reduce the "amps" but you can set to shut off when the water reached the desired temperature. It will of course come back on if the water cools off. Also, you have to keep water in contact with the heating element and the thermostat bulb or the element will continue to heat up.

Since you don't explain what your end goal is, I can't advise you on the safety of what you are doing. I would suggest that given the possibility to over heat if the water runs out, you should have a float switch to prevent the element from coming on without any water in the container.

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what\'s the reason?
For if it prosper, none dare call it treason."

"Follow The Money"  ;-P

In simple language, the resistance of the heater is very low, about 1/10th of an ohm, so it sucks lots of current. If you must use that heater and cannot modify it to increase its resistance, you have to lower the voltage, since voltage is what drives current through resistance. Or you keep the voltage the same, but pulse it on and off rapidly, so that the average voltage is lower. But when it is on, the current will still be the same, unless you add a filter to average those voltage pulses before they get to the heater.

By the time you have gotten the power turned on and off many times per second to lower the average current, it is pretty simple to also add a timer to terminate the pulses after some amount of time.

Is the point of this exercise a secret, or can you tell us what you are trying to accomplish?

--
Regards,

John Popelish

This is really more of a "basics" question than a "design" question. You also have a "design" question later.

First make sure you are reading this with the right font. The "*"s should line up in the lines below.

*MMM*MMM*MMM* *III*III*III* *---*---*---*

Change the font until they do.

The term series means like this:

Wire More wire 3rd wire ------[Item1]------------[Item2]------

If you connect two identical resistive heater in series, the total power and the current will be reduced in half. Each heater will end up with 1/4th the power going to it.

I =3D V / R

I is current V is voltage R is resistance

Hooking stuff in series makes the resistances add.

P =3D I^2 * R

P is power

You can buy a thermostat that kicks off at 100F. If you wire this in series with the heater (and it can take the current), you will have something that turns on until the water heats above 100F and then off until it cools below 100F. It will cycle on and off holding the temperature in a narrow range.

If your thermostat can't take the current:

look around page 2063

Digikey may also have the thermostat you need.

If you can live with very inaccurate timing, you can use a second small heater and a second thermostat and a relay. A push button will start the timing.

Hefty push button ! ----- ---O O------- ! ! ! ! ! Contacts ! ! 0f relay ! ! / !

+12V -+---/ O--------+---+-------- -------------> To heater ! [Therm] [ostat] ! +------------ ! ! ) [Small ] Coil of ) [heater] relay ) ! ! GND GND

When the button is pressed, the relay contacts close because its coil gets power. As long as the coil continues to get power, the contacts will remain closed and the heater will remain on. If the +12V input goes away, the relay is de-energized. If the small heater heats the thermostat hot enough, the coil gets de-energized.

The thermostat and small heater should be inside an insulated housing. Screwing them both down onto a block of aluminum would be how I would hold them in place. The more aluminum in the block, the longer the delay.

This is extremely crude but these sorts of things are hard to break.

Thanks for all the replies. You're right, it might help if I explain what I'm doing.

I am going to make and experiment with an HHO electrolyzer for my car. I'm thinking ahead to winter time. I do not want to adapt the heating coil I used as an example; I want to have a stainless steel

1/4" threaded rod as a heating element, about 1 foot long running through the tank. I don't want the rod/heating element to get more than about 120F because it will go through, with sealant, the acrylic case.

I found this circuit which is supposed to turn on a heating element (he uses a metal plate under his electrolyzer "jars") until the temp reaches 72 , then turns off (he also incorporates turning on a fan at

115 but I am not doing that).

I don't understand how it is "set" to turn off at 72. (well I don't really understand the schematic itself.)

I want to have a small in-car control unit which displays the temperature of the electrolyte with LCD or LED readout. I found this link

It says it can be fitted with an external probe. He will email a schematic if I email asking, but the picture looks like it requires a much bigger board than the readout itself. I want to keep the control unit as small as possible. I also found this:

It has a 10 foot probe wire which is long enough to reach into the cabin, and the probe is stainless steel, also a requirement. But the LCD is not lighted so it's hard to see (for that reason, I'd rather have an LED display), it is battery powered but I want to use vehicle power, and no "output" to use to set on/off for a heating element.

The way I want this to work in wintertime - or maybe I'm dreaming to think I can do this - is like this:

Car off:

1. I know I'm going somewhere in about 20 minutes, so I go out and push a momentary button to turn on the heating element. It heats (LED shows it is on) until the electrolyte temp is about 70, or about 10 minutes auto-off (like the rear defroster), in case I change my mind about going somewhere

1. I go out to the cold car in wintertime and drive away, the electrolyzer power switch is on - it's always left in on position - but it still doesn't go on until the temp reaches 60, then its LED shows me it went on. The heating element goes on, an LED shows me its on, it stays on until electrolyzer reaches about 70.

2. As noted, heating element must not get hotter than 100-120.

Is this doable?

Thanks, Buddy

"buddy " = TROLL

** Say no more.

This absolute, know nothing loon thinks perpetual motion is a reality.

Probably talks to space aliens and practices Scientology as well.

Ignore this ridiculous TROLL

..... Phil

Cars are very bad experimental platforms. I suggest you get a lawn mower engine and build some what to measure performance and the fuel use. On a car, it is very hard to measure anything or even hold things constant.

There really is no such thing as HHO it is a scam that that been running around the internet for some time now.

Adding plain old H2O to the air going into an engine does improve the performance. This is doubly true if you can adjust the compression ratio and timing and detect the onset of pinging. You need to make sure that the water is vapor or at least a very fine mist that does not settle out on the metal parts. Water drops will break stuff.

Breaking the water into H2 and O and then feeding it into the engine can give you some gain. The numbers on this aren't very good because it takes more energy to break the water apart than you get back by simply burning it. It can change the chemistry of what goes on in the engine an make more of the other fuel you put in get completely burned. If done exactly right, this will improve the efficiency enough to make it almost worth the bother.

Go with the simple thermostat that you can buy if you want to continue down this path.

I have one on my car now, a simple design using 3" pvc tube, for 3 tankfuls of gas, about 750 miles. Increased mpg from 19 - up from

17.5 after switching to synthetic trans fluid and adjusting my driving style - to 22 "city" (which is all I do) Very consistent driving habits, routes, fill-up procedure. That's about a 15% gain. I spend about $400/month on gas, so saves $60 /month. I have carefully monitored several things and see no ill effects.

The one I am building now is a more efficient design and will fit better, if it increases mpg great, if not I'm happy with the 15%.

But as I said, it doesn't have any outputs to turn on/off a heater.

I will experiment with wiring heating rods in series as you described in your earlier post. But I would still like to control it as I described, rather than manually as I would have to do if I only had the thermometer I linked to.

Thanks, Buddy

Let me add to your slightly negative evaluation ( I'm more negative). The system starts with a battery that is LESS THAN 100% EFFICIENT( you don't get out what you put in). Then you run current to a hydrogen (or hho) generator, it is my understanding that these things produce heat among other losses. So the hydrogen generator is LESS THAN 100% EFFICIENT. Now let's run the hydrogen into an internal combustion engine, oh, did I mention that the engine is LESS THAN 100% EFFICIENT. Ok, now this engine turns an alternator that is LESS THAN 100% EFFICIENT. The alternator charges that battery that we already talked about. So I don't see where the payoff of the system is coming from. If anyone would like to add efficiency numbers to the LESS THAN 100% EFFICIENT components (battery, H generator, engine and aternator. I would be interested to see them. We need leadership that will start us toward energy independence. Nuclear, Better battery technology, oil from Algae, and maybe this Butanol. What do you think about butanol?

Mike

I remember a device from a few years ago that injected water onto the hot exhaust and fed the steam into the intake ! I have often wondered whether it worked to improve fuel economy at all.

--
Best Regards:
                     Baron.

Steam!?!? I know that jets taking-off from Phoenix often inject misted water to cool inlet air and raise the density. About once or twice a year it's too hot to take-off from PHX.

...Jim Thompson

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| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
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        Democrats are so cute.  Stupid as bricks, but cute.

That's more an air-over-the-wings density issue.

Mark L. Fergerson

I take it from that, its just more snake oil then ? I didn't know about the water misting use by jet aircraft though !

--
Best Regards:
                     Baron.

snip

simple physic will tell you that you that you can't get more out than you put in, so the most efficient thing to do would be to throw it away, less weight to drive around with ;)

-Lasse

I don't believe you. This doesn't mean that I think that you are a liar. It is just that there are so many ways that you can be fooling yourself and the ourselves are easier to fool than others.

You number of a 15% increase is extremely suspect because it is large enough that we are getting into the area of the impossible. The efficiency of an engine depends on things that you would have a very hard time changing. The temperature that the burning fuel reaches and the temperature it goes down to just before the exhaust valve opens are two very important ones.

Since you know when you are doing the experiment, you are almost certainly driving differently than normal. Did you know that wearing a green hat reduces your fuel usage. Get a green hat and try it. Keep very careful records of the weeks you wear it and the weeks you don't. I can assure you that you will see a difference in the numbers. Humans by their nature can't repeat things well or hold things constant. It is part of what makes us better than machines in so many ways. It is the one small downside to being a human scientist[1].

[1] That is if you don't count never getting the girl at the end of the movie.

You don't need an output. You put the thermostat up against it.

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You missed the important point about adding H2 and O2 to the engine. This changes the chemistry of the burning of the hydrocarbon so that it gets more completely burned. This means that it only works on engines that don't burn all of the fuel, but such engines aren't hard to find. Usually they are under the hoods of cars. You will find that the losses from adding such a system are less than you expect because of this.

anol.

I'm at the I'll believe it when I see it stage with that one.

e

It reduces the amount of pinging. This lets you run a higher compression and advance the timing. As a result you get better milage but the effect is indirect.

No it is a lack of thrust. As the Saturn 5 proved, you don't need wings if you have enough thrust.

I didn't miss it, I'm just not ready to think a quart jar of water under my hood is going to increase my gas mileage. I've had three people approach me telling about there improved mileage or asking asking how to improve the system (one of these on a diesel boat). But I'm willing to see some real science on the idea, not just anecdotal evidence. And as you said "I'm at the I'll believe it when I see it stage with that one." Thanks, Mike

I think I read somewhere that it wasn't really too hot to take-off, it was just that noone ever bothered to make the temperature take-off thrust charts go to a high enough temperature, so a few times a year it goes off the chart.

-Lasse