But a few years ago, I decided it would be nice to steady down that oscillating ammeter, and to this end, I tried putting a likely-looking capacitor from my radio junk box into my charging circuit. It didn't make any difference to the wildly-waving ammeter needle, but it did have one effect, which I discovered a while later.
My bike starts with a dead battery! Since then, my battery has gotten old, and it doesn't hold much of a charge, or for very long. Last fall, I noticed once that the charge was so low it barely lit the running light; when I turned on the headlight, they both went out. So I was a little apprehensive when I turned them both off and kicked it over (key on, of course) and it started first kick! I rode it home, and by the time I got there, the battery was up enough to run the lights just fine.
When I rolled the bike out of its spot in the shop this spring, the battery was stone cold dead. I'd trickle charged it a couple of times over the winter, but no matter; this time it would take no charge at all. Living as I do mail-order distance from the nearest motorcycle battery, I attempted revivification. I drained out the acid, and replaced it with fresh, and this got things so that the battery would take a 4 amp trickle charge for an hour or two, and light the headlight after a 24 hour wait. But the voltage was down after 24 hours of standing to less than 11 V. And after 48, it was down to under 7 - barely enough to light the light. The next day, it was down so low it wouldn't even do that, so I thought this would be a good time to see what effect the capacitor was having on the system.
I pulled a plug, leaving it connected sitting on the cylinder head.
Turned on the ignition and kicked it over. The plug gave a
series of lovely bright blue sparks! This with a dead
battery still connected! Am I now a believer in capacitors? You
What Kind of Capacitor?
The one I used was just an electronics part, a Mallory 40000 ufd
electrolytic with a 40VDC rating (peak 50V). Size is the determining
factor in capacity with these things, apparently, and it's physical
size is about 4" X 1 1/2". (10 cm X 35) You can use one like this,
or you can buy the Lucas one, if they're still available. Either
way, I won't be going anywhere without one anymore!
If you decide to use one, be sure to observe polarity when hooking it up - it's marked, and if you use an electronics one, you'll have to solder the wires to the terminals - the Lucas ones come with spade connectors. Other than that, there's nothing to it. I strap-tied mine to my wiring loom in a fairly vibration-free spot, do that and Roberta's your Auntie! ---