jadz

This page shall cover the details of my home made electric vest for use on my motorcycle. I got the idea from my uncle who made a very similar vest and even gave me his left over wire.

The vest is composed of the following items:

• Two used fleece vests ($8.00)
• 30 AWG multi strand Teflon Coated Copper wire($0.00, donation from John)
• flexi-cord from Princess Auto ($4.99)

To make the jacket I first measured the resistance of the wire (this is done using a multi-meter and the longest piece of wire you can find, the longer the wire the more accurate your results will be.

Because my current ride (the ZR-7S) has limited power for accessories, I wanted to limit the vest to ~ 35 Watts. This is where a little math will come in handy.

Measure the resistance of the longest length of wire you have (i.e. if you buy a spool of 100 feet measure the full length). If you are using 30 AWG multi strand wire you will likely end up with about 0.1 Ohms/foot.

Most commercial vests are in the 35 Watt range, which will give you a length of wire that you wish to use. We will also assume that we are getting 13.5 Volts from the bike while it is running.

P(ower in Watts) = V(olts) * C(urrent)

and since C = V/R we have

P = V*V/R

Example Calculation with 35 Watt vest:

35 (Watts) = 13.5 V * 13.5 V / R

35 = 182.25 / R

35 * R = 182.25

R = 182.25 / 35

R = 5.2 Ohms

Length of wire = 5.2 Ohms / 0.1 Ohms/foot = 52 Feet

Generalized Equation (assuming 13.5 Volts and 0.1 Ohms/foot)

R = feet * 0.1

feet * 0.1 = 182.25 / Wattage

Feet of Wire = 1822.5 / Wattage

After putting it all together I now have a toasty warm vest that draws 35 Watts and keeps me warm on the cold days.Teflon coated wire will be a lot safer (it is used in frying pans after all, and can withstand higher temps).

Common wire is insulated with PVC, which has a melting point of ~ 130°C where as Teflon has a melting temp of ~275°C.

The smaller the gauge wire you use (which will be the higher the AWG #) the more resistance per foot you will result in. I think that the 30AWG worked out nicely as it wasn’t that hard to put in the length of wire I needed.

I put over 50% more length of wire on the front vs Front and also wired the collar of the neck.