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Make Your Own Heated Motorcycle Handlebar Grips

I guess it's unlikely that anyone would repeat this project now-a-days with aftermarket bar grips being so easily available but all the same it's an interesting short article and may still prove useful (not to mention demonstrating the ingenuity of some people:-)

Some maths:
2.4m of Constantan wire @ 4.2 ohms/m = 10.08 ohms [assuming the 4.2ohms figure quoted beow is correct]

Ohms Law: I=V/R
therefore: I=12/10.8 or for a fully charged battery with the engine running more typically I=13/10.8 (voltage 13+ volts ;-)

So: current (I) will be between 1.11amps and 1.2 amps (I'll use the 1.2 figure)
Therefore: power (IxV)=14.4 watts

Typical after market retail heated grips will use between 30 and 36 watts per pair (at 12.0 volts). So, 14.4 watts per grip for the DIY heated grips would appear to be close to the retail heated grips :D Of course there will be variables such as the material the rubber grips are made from (insulating / heat transmission properties) but in theory at least you should have a set of grips with a similar heat output to off the shelf items :-)

A useful link:
http://www.ohmslawcalculator.com/ohms_law_calculator.php

At risk of stating the obvious, if you're not careful there's the potential for damaging your motorbike's electrics at least or setting it alight at worst !!
 

Make Your Own Heated Motorcycle Handlebar Grips

By 'Ebbo' Mar2003 (original article here)

This is the method I used over 10 years ago to put heated home made handlebar grips on my BMW R100RT motorcycle. It's based on using Constantan resistance wire from Maplins. This wire is a copper/nickel mix giving a resistance of 4.2 ohm per metre. It takes solder very well so attaching your wires is not a problem. With a 2.4m length of wire the grips are on the warm side at 17.9 watts each (current draw approx 1.5A each). 

 
Method:
Take the bar grips off on both sides. On the clutch side only, wrap with 2 layers of masking tape evenly, for electrical insulation.

Take a 2.4m length of Constantan wire and make a loop of it. Start coiling it on to the bar starting from the inside and working very evenly toward the bar end, See below, it's a double coil so that both ends of the wire are at the end of the grip.

DIY heated motorcycle handlebar grips

The diagram above is only a guide. You will have lots of windings about 3 to 4mm apart, keep them even and they must be keep apart. If they touch it will be a very very hot spot so take your time!

As a guide to putting the windings on, form the wire in to a loop evenly, tape the 'closed end' of the loop to the bars with a small piece of masking tape, then start winding the wire. After you have got a few turns on, fix them in place temporary with a piece of tape otherwise you will go mad when they spring back, and they will!

Finally, cover the windings with one layer of masking tape, removing the temporary tape as you go.

Running the wires
You will have to provide a 12v supply up the inside of the bars (red/blue wires in the diagram) it's preferable to solder the constantan wires to the ends although you could twist them together but I don't know how long that might last. Insulate with masking tape carefully and tuck the wires neatly back up the bar end, then replace the rubber grips carefully.

IMPORTANT: you must make the connections on the bar end, not off the end as indicated in the diagram above. This is to ensure that the Constantan wire is properly supported against shorting and breakage.

To exit the wires from the bars you need to drill a hole. Unclamp the bars and twist them back toward the seat, you will have to detach the brake master cylinder and the clutch cable or master cylinder at least. Centre punch the bars in the middle of the bar clamps and drill a hole large enough to let the wires out. With a small round file tidy up the hole so the wires wont get chaffed or cut. After the wires have been run and the bars are swung back up, the hole and wires should be mostly hidden.

If your bike is a BMW you might be able to wire them directly to the bikes heated grip wiring if present and use the 3 position switch to get two heat settings, otherwise you will have to provide your own fused supply that becomes live when the Ignition is on.

Very Important: You must protect the bikes wiring with an in line fuse. A 5a fuse should be ok.

Some Ohms law for you entertainment!

2.4m of Constantan wire @ 4.2 ohms/m = 10.08 ohms

12v / 10.08 ohms = 1.2 amps

12v x 1.2 amps = 14.4 watts, Toasty warm!

Link to an online Ohms law calculator

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