DIY heated gear

Linkex

Linkex

Linkex

Associate
Joined
4 May 2011
Posts
1,065
With winter approaching, I've been reading up on diy heated gear. The process seems fairly simple, but there are a few things I’m not sure on. Firstly, most of the things I've read are based on voltage against length of wire to control the heat. While this looks like it works, it means that I’m stuck with 30 feet and will have no temperature control. If I want to do a pair of heated gloves for example, I can’t fit 30 feet of wire in there. So, I assume I need to fit something to lower the voltage if I want control, or shorter runs and this is where my electrical skills fall down – I don’t know what I need. A variable resistor? Some kind of transformer? – what thing do I buy that takes 12v in one end and lets me choose the volts out the other end?

Secondly, I’m concerned about power draw budget. I’m looking at around 50 watts per 30 feet. Assuming I did head to toe covering (I’m not going to, but this is worst case), I could be trying to draw 150 watts from the bike. I know bikes will all be different, but what sort of range should I expect? Is 150 watts reasonable from any bike, only big bikes, or that be too much for any bike? If it’s out of reach, what sort of spare wattage would a 600 generally have?
 
Thanks Dogbreath, that's exactly what I needed to know :)

Just to check my understanding - if I run 12v through 30 feet of RS Components Part Number 177-0621, it will generate around 50 watts of heat (According to the article I’m looking at). Does that mean that 6 volts through 15 feet of same will generate 50 watts of heat? And if that assumption is correct, is there any such thing as a non-variable switching or PMW voltage regulator? The reason I ask is I’m trying to figure out if I could run 30 ft in a jacket, 15 ft in my gloves, have 2 sets of wires coming off the variable controller, 1 to each, but with a static regulator between the controller and the gloves. The idea being that I then have a single controller for both jacket and gloves, without putting to much juice through the gloves circuit.

Or am in totally the wrong ball park?
 
ShakenNstirred said:
what sort of mileage are we talking about?
jacket n trousers with a thermal lining, winter boots and a good pair of glove are all that really needed.
handle bar covers or heated grips an option also.
you don't want to be running the generator near capacity or it will get very hot and shorten it life also your mpg will be higher with all the extra drag
Click to expand...

Um, I don't think that's how motorcycle generators work...
 
The drag caused by the drawn current would be absolutely insignificant and even if it weren't, the rectifier draws all the current whether it then passes it on or burns it as heat, so adding load on to the rectifier isn't going to change that anyway.

I appreciate your input, but commercial heated gear exists, so its clearly viable. If you have constructive criticism about the parts I want to use or my approach, I'm all ears, otherwise, I'd like to get back on topic please:

Linkex said:
Thanks Dogbreath, that's exactly what I needed to know :)

Just to check my understanding - if I run 12v through 30 feet of RS Components Part Number 177-0621, it will generate around 50 watts of heat (According to the article I’m looking at). Does that mean that 6 volts through 15 feet of same will generate 50 watts of heat? And if that assumption is correct, is there any such thing as a non-variable switching or PMW voltage regulator? The reason I ask is I’m trying to figure out if I could run 30 ft in a jacket, 15 ft in my gloves, have 2 sets of wires coming off the variable controller, 1 to each, but with a static regulator between the controller and the gloves. The idea being that I then have a single controller for both jacket and gloves, without putting to much juice through the gloves circuit.

Or am in totally the wrong ball park?
Click to expand...
 
Dogbreath said:
You you certain that's the correct RS code? It is described as basic hookup wire, not resistance/heating wire which I was expecting.

Power = V^2/R

If you half the resistance (half the length of wire) and half the voltage, then you get 1/2 of the power. To get the same power from 1/2 the length of wire, the voltage needs to be reduced by a factor of 1/sqr(2)=0.707. 12*0.707 = 8.5 volts, as close as damn it.

You can certainly build a non-variable switching regulator, though for the currents you are looking at a ready built module might be expensive. You could simply use the variable speed motor controller and replace the potentiometer would a couple of fixed resistors, which would be a cheap and simple way of doing things.
Click to expand...

Its the RS code that's mentioned in this article - http://www.hastie.org.uk/heatedjacket.html - chosen I think for its low cost. I wasn't aware that you could get wire specifically for this, will have a hunt around. If you have any specific recommendations, please let me know.

Took me a minute to get my head round that maths, but now I have, it’s actually a much simpler formula than I thought it would be to calculate the volts for different lengths of wire, thank you for that.

I’m now thinking that rather than trying to add multiple volt regulators in and running a master regulator, I will create a bike mounted project box, and add one PWM voltage regulator per body area (So, head, legs, helmet/gloves, feet) and a master on off switch. That way I can adjust specific body parts on the fly, rather than trying to pre-set relative temperatures. Plus, it should be a little simpler.

Now I just need to figure out what sort of connector to use and I can get started.
 
Cheers. Have ordered the parts to get a prototype up and running, will prob create a new thread for it once I start building.
 
You must log in or register to reply here.
Back
Top Bottom