wiring up for a heated jacket

To show whether the alternator is keeping ahead of the game you could fit a small digital voltmeter across the battery. I have one on a Commando that is taken from the feed to the light switch and then earth. It effectively shows the state of the battery and if the alternator is coping then you would expect to see a steady voltage around the 13v mark. If it starts to drop, start switching things off. I have a fat wire running the length of the bike dealing with earth rather than the frame. (how does electricity complete a circuit through the headstock bearings covered in grease?)

Yes Robert. If you want to monitor the total balance* of power being used, the jacket wire should be on the same side of the Ammeter that is fed from the rectifiers output (as you suggest).

The other side of the ammeter should feed the battery only or any other electrical item you want constantly connected to the battery without showing its current consumption on the ammeter when in use...(not recommended but sometimes the stop lamp is wired this way)

* The sum difference of the alternators output and the batteries output (or charging current) vs the consumption of the bikes electrical loading.

Also note that the bikes ammeter is only there to indicate what current the BATTERY is receiving or giving out...NOT the generator's power output.

Les

Don't worry about overloading the Lucas alternator as their "drooping" voltage characteristics means they can even drive a short circuit without heating up too much. In fact some wiring systems deliberately short out some coils to lower the magnetic flux across the other coils to reduce the power produced in them. So you will either have enough power to heat the jacket and gloves or not and this will be shown on the ammeter as a discharge from the battery if the alternator fails to produce enough power to balance the load, but no damage done to the electrics...as long as the wiring can handle the drain current that is....you can fit a safety fuse.........Les

You could wire it from the battery side of the ammeter (like the horn and stoplight) then the fluctuation won't show up on the ammeter.

Strange as that's exactly why the horn and stoplight are wired on that side. Although I must admit I'm thinking about dynamo rather than alternator.

I would be tempted to remove the ammeter from the system completely (leave it there for show if you like) If it's anything like my ex Commando a wire went from the battery (under the seat) to the ammeter, back to the ignition switch (Under the seat) up to the headlight switch and the coils etc. a lot of wires that you don't actually need and each connector giving you a potential ( scuse the pun) voltage drop or circuit break. My 3 phase alternator would do the job nicely and charge to a sound 14v at about 1800rpm loading up with lights was no problem and Oxford heated grips could be turned down in traffic when revs were not at a sustained 2-3000rpm. worth looking at whether your sidelight bulb is on when the head/main is on and off loading some smaller bulbs with LEDs. My personal opinion is that LED headlight bulbs are lacking in a quality beam. Like a lighthouse in the desert, brilliant but useless

Hello Robert,

I have a Widder heated jacket. It was supplied with a thermostat and it can also be connected to pants (they are chaps, actually) and gloves. I ran a direct pair of cables to the battery with an in-line fuse. When riding my Mk III Commando during the day everything is fine but once it becomes dark things are much more challenging. Travelling at below 55 mph the headlight begins to shine less brightly and the heat in the Widder clothing diminishes. As the headlight becomes dimmer I have to ride even more slowly (I ride on mainly unlit, country roads) and consequently the amount of current going into the heated equipment will also diminish as the alternator provides less current at the lower speeds. So I end up going slower, for longer, with less available heat and light from the headlamp. If I turn up the thermostat the headlight becomes very dim. I suppose I have reached the limits of the original performance from the alternator, rectifier and zener diodes. Being realistic, an ammeter showing me just how much current I don't have might be useful .

Good luck and do let us know how effective the jacket proves to be - they are probably designed for much more modern machines which have more available power.

Colin Cheney, Leicestershire.