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Hi,

On my Jawa 350 I currently have a 6V 100W electrical system with non points ignition, the spark is made by a pick up sensor and two trigger points on the generator rotor. The system has 100W exclusively for the non ignition realted bits, and the bike can be run without a battery.

Nevertheless 100W is not much to play around with and I currently have the following in use on the bike:

35W/35W Headlight bulb
10W Rear light
15W Brake light
10W indicator bulbs
and 4W pilot and dash lights.
So during normal use the sytem is using 35W+10W+4W=49W and often an added 40W for braking and turn signals. That makes a total of 50W to 90W in use.

Could this explain why the battery goes flat after about 300km of riding? I have long been trying to figure this out but can't. I recently rewire the bike eliminating some useless loom parts, but although each bulb burns better now, the battery still goes flat (new battery too) And the reg/rec is putting out the correct voltage to charge.

I have also been pointed in the direction of the ignition switch. It is a very simple design and not well suited to handling great current. Since everything is wired through the ignition switch, except ironically the ignition, and there are no relays, maybe the exessive current is being so restricted that the whole system is drainiing. In that case would a relay for the headlight help??

All advice would be appreciated, and sorry for writing an essay.

Cheers

Nothing wrong with an essay, more info is way better than not enough.

Your ignition is seperate from the rest of the electrical system, those pick-ups only generate spark. There is probably a generator built into the flywheel to make juice for the lights/battery/etc. And if the regulator is giving proper output, then that part is likely working OK.

The battery could be pooched. Or you could be dumping juice to ground, through the ignition switch or some other bare/broken wire.

The battery could be dead, but its the third battery i've had in the bike with the same problems. So i dont know what the chances are of having all 3 faulty ones, but slim I would think. As I reviewed the wiring before, I will take a bet that the ignition switch is the problem. Time for a new one anyway, as the current on can be turned on with basically anything.

3 bad batteries is pretty unlikely. And it sounds like it's time for a new ignition switch....

You could have an open circuit going from the alternater to the batt. and you are not getting any charge into the batt.

niterider wrote:You could have an open circuit going from the alternater to the batt. and you are not getting any charge into the batt.

Um, no. The alternator goes to the reg/rec and then to the battery straight from the reg/rec. Anyway the battery charges ok without the headlight on, but since the law says that the headlight has to be one all the time, its not helping. The worst is in slow traffic, where the revs hardly go above 2000rpm, and a lot of brake lights is used. About 20minutes of that will drain the battery.

I think that you are not getting the right amount of current out of the alternater and the regulater. That system is designed to work right even when the head light and brake light are used at the same time. If the batts are new you must have a problem with charging system.

Gotta remember, this is a Jawa with a 6 volt system. Never an overly potent charging system right from new. More like an old mid-60's bike from England used to have... and it's well known that they sorta sucked then.

If you truly have a generator, rather than an alternator, you're probably just overtaxing the charging system. Although the generator may be rated at 100W, that is probably only available at a high rpm. Unlike alternators, generators do not make much electricity at lower rpms.

My guess is that all of the time you're using 50w of electricity, you're not generating that much with the generator. The battery has to supply the difference. If you're doing a lot of riding in town, rather than on the open highway, this will eventually discharge the battery. I had this same problem on an old generator equipped BSA that I used to ride to work. Every three weeks or so, I had to recharge the battery.

Is lower wattage bulbs a possible solution?