Friday, September 20, 2013

Relocating the Battery to the Sidecar

The sidecar tub has a couple more holes in the body as of yesterday evening. I relocated the battery to the sidecar for the winter. Or more accurately, removed the wiring from the stock battery and added in a larger one. I removed the seat in the sidecar since no one would be riding in it in the winter anyway. It is only held in with a couple of wing nuts to bottom of the sidecar. A couple of ¾" holes were drilled into the body where they would be below the bottom of the seat if it were put back in.

The ground wires were removed from the battery and relocated to a bolt installed into an unused hole in the frame behind the side panel. Fairly flexible 4 AWG cables were threaded from the positive battery terminal and the new ground post to the sidecar through rubber grommets. I believe the cables were sold for use with high power car stereo installations as the cables were made from numerous fine strands of copper wire. This would explain the flexibility and should be very low resistance. The original battery is no longer in the circuit and will be removed at some point once I figure out a better positive terminal.

The new battery is a group 24 automotive flooded lead acid battery which is rated at 800 CCA. Quite a bit more than the Odyssey battery at 330 CCA. Either should be more than enough for the bike. My old airhead only has a 280 watt alternator and it had difficulty last year keeping the battery charged especially during the winter commute. With the larger battery, I shouldn't need to worry about it and use the heated gear and grips with impunity. I'll just plug in the charger periodically.

The maintenance free battery is in a plastic battery box held down to the floor with a nylon strap. I believe the box was designed for use in boats and RVs. I mounted it close to the sidecar wheel to take advantage of the additional weight as ballast to help keep the wheel planted during right turns. No battery heater installed yet as I needed to see if there was room for a battery blanket inside the plastic box. I will be adding a piece of closed cell foam under the battery as insulation. 


  1. Looks like a clean install job Richard! A little ballast never hurts, especially when it's the battery for your tug.

    1. Right, a little ballast never hurts anyone. I was originally trying to figure out how to add a permanent location for a car battery. I am thinking of reinforcing the frame between the bike and the car by welding in some steel square tubing between the sidecar mounting points and the cross members. This would also provide a mounting location for a battery shelf that will hold the plastic box. Plus, I would be able to eliminate the clamps for the struts. I think that these are the weakest points of the mount.

  2. Richard:

    I think that will solve your starting problem, more cranking amps during cold weather. Is it a deep cycle battery ? was just wondering

    You could also get a 2nd RV battery with the "isolator" circuit to power your heated gear and just charge it every few days

    Looks like you are getting it set up for winter riding. Next come the studded tires again

    Riding the Wet Coast

    1. It is not a deep cycle battery or even an AGM battery. Just a standard, automotive battery. The old Odyssey PC925L was rated at 330 CCA so it wasn't no slouch. Plus, I added a short metal bar to the negative terminal of the Odyssey battery so I can always "jump" the bike with a single jumper cable between the metal bar and the new grounding screw. If I continue to have starting problems, it's time to take apart the starter. I've learned that there is a brass bushing in the nose which, when worn, causes the starter to drag.

      Tonight, I'm pulling the rear wheel to put on the new Heidenau K60 which has enough tread to install the carbide studs. Still thinking of what to do for the front...