Help. Electrickery Question

[packapoo]

My basic knowledge of electrics wouldn't fill a postage stamp....

Looking at a heat pad designed to run from a motor vehicle system (12v). Cord plugs into cigarette lighter system.....Would it work hooked up to household power via a 12v transformer?

In car it would be DC (yes/no) whereas household is AC.

Supplementary question is are all 12v AC plug-in transformers created equal

So far it sends my (12v) temperature controller into a frenzy as it tries to heat and cool at the same time - red lights go mad.
Cig lighter plug has a fuse within and some diodes(?) and is two wire to an in-line three position switch - off/hi/low - then is three wire to the pad.
I'm trying to run it thru a household outlet and plug mounted on my controller box, but perhaps using original supplied plug and find myself a female cig type socket to fit to controller box would be the go?

Any comments appreciated, even if 'Dickhead' comes to mind.....

[Myles]

If it is intended for 12vdc then you have to run it on 12vdc.

You arent trying to run it from a 12 volt charger are you? That wont work. You need a 12 volt power supply. Not the same as a charger.

[Admiral Toad]

You need to make sure whatever power supply you are using will produce enough output at 12 volts to power the heating mat
Try and see what power or watts it is and what is written on your supply
Power (watts)= volts x a current (amps)

So a 24 watt heater needs at least a 24 watt power supply or one that produces at least 2 amps (2amps x12volts=24 watts)

[Mash]

Can you post a link to it. We could then make some recommendations.

[packapoo]

Thanks for your considerations fellas.

What I have learned is this thing is just not going to fly....

That the blanket is DC and I'm trying to power it AC apparently doesn't matter, it should work. BUT the blanket draws 4 amps and my charger's output is measured in mA (milli-amps?)so if I'm reading it right, heaps of grunt short....Which is what I think the Admiral said.

Bother!

[Easydrinker]

Please stay safe!

Robert.

[packapoo]

Oh I intend to Robert, thanks

One of my muddled thinking reasons for going the 12v way........

[Admiral Toad]

4 amps is 4000 milliamps so if less than that it won't warm up properly

You ideally want something about 5 amp

Give your local maplins a try

[Myles]

That the blanket is DC and I'm trying to power it AC apparently doesn't matter, it should work.

Oh it matters all right!!

Take a 120v ac 1000 watt heater and run it on 24v dc and it works but only gives you an output of 40 watts.

The same works in reverse. Your 40 watt heater suddenly gives out 1000 watts, but probably not for long.

Calculate the voltages and currents carefully.

[Myles]

RMS is the ac alternative that gives the equivalent output of the dc.

You need to run a 12 v dc device on 17 v ac to get an equivalent output.

(16.96 v ac = 11.99 v RMS)

Personally, I would recommend that you get a dc power supply or appropriate ac heaters. Soil heating cables work for me at about 75 watt per metre, on 240v ac.

[packapoo]

@Admiral...learned a bit along the way, as you said more grunt needed, working on it. But not Maplins, don't think they're south of the equator...

@Myles....I should have explained myself clearer when I said it'd work. It won't be optimal but with appropriate grunt applied, which I don't have presently, it will suit my needs.....

Mulling over a better brewing set up (shed) but other things in the way so making do presently. If my shed was thermally sound would be simple to just place an oil heater in there hooked up to my 240V temp controller.

As I have to go for a beefier power supply, uncertain whether to settle on a 4A which is what the heat pad draws or go 5A for margin. Cost difference minimal.
If I hadn't come upon a 12V temp controller when I was looking for another 240V unit it would have been soooo much easier.

[Mash]

If you are outside what about a brew fridge.

Recipe..
1 old upright fridge
1 small heater
Mains cable

Peel unnecessary stuff off the outside of the fridge.
Stand in shed.
Lightly prick outer skin to allow airflow.
Stuff with heater
Combine with enough cable to activate.

Use as required should last for years.

[packapoo]

Thanks Mash - am on the outlook...

[packapoo]

Purely FWIW.....

Finally got temp controller and seat warmer going today.

Problem was the replacement power pack I ordered was DOA when it arrived. In a war of words over that - 'It's completely unheard of'...Well, have I got news for you.
They finally agreed to replace it but I got tired of waiting.

Saw somewhere on here question over whether a lighting transformer would be suitable so sought advice from family Lekky over in Oz (which I should have done when I kicked this off...) It does.

12V 60W down-light unit. Works well and is nice and compact. Oh, and cheap.

[Easydrinker]

I am pleased that you got there.

Robert.