Topic: Dead electricals....... Troubleshooting Help

[CoachDoc]

My '74 550 had been running like new until this morning. I kicked started the bike and it started right up. I rode it about 1/4 mile to a stop sign where it stalled. I saw the oil and neutral lights, but when I pressed the start button there was no response and everything went dead electrically.

This afternoon I towed it back up the hill to my garage and took a look with my multimeter. The battery was putting out 12.82 volts with the ignition switch off. Turn ignition on and the voltage goes down to almost nothing. I replaced the main fuse and no change. Also, removing first the 5 and then the 7.5 amp fuses and still got almost no voltage at the battery when the ignition was switched on. Short? Bad battery? I have checked the battery connections and the ground cable, which seem ok.

[scottly]

Are you measuring the battery voltage directly at the battery posts themselves? If not, please do so, and report back.

[CoachDoc]

Are you measuring the battery voltage directly at the battery posts themselves? If not, please do so, and report back.

Scott, yes I am measuring at the battery terminals. With the ignition off, I also measured the voltage between the positive terminal and various points on the frame and I still get 12.82 volts, which indicates to me that the battery ground connections are good.

[scottly]

Bad battery.... Is this a gel-cell? I've seen similar behavior with them, where unloaded they have a good voltage, but under the least load the voltage drops a huge amount.

[CoachDoc]

Bad battery.... Is this a gel-cell? I've seen similar behavior with them, where unloaded they have a good voltage, but under the least load the voltage drops a huge amount.

Yes, a relatively new AGM battery. I'll try it out tomorrow connected to the battery from one of my other bikes.

[scottly]

BTW, if the battery was good and there was an excessive load (short) that was only present with the ignition switch turned on, it would have blown the main fuse.

[strynboen]

 take the battery off the bike....and test it vith a 50W bulb(can be taken from the main light)..if it lights up the battery are fine


if it not lights up..the loading system have not worked at the last trip....
if it lights up....there are problems vith fuses or main schvitch or solinod(or kontakt who takes power from the one terminal at the solinod

[CoachDoc]

I disconnected my battery this afternoon and hooked up to my car battery (non-running) with cables to my bike's battery cables. Bike fired right up and ran perfectly. The battery must have an internal short........can be charged to good output voltage but when any load is applied it fails totally.

For what it's worth, the battery is only 16 months old, a Bikemaster AGM. Out of warranty, so it's on to a new battery. Right now I'm undecided about another AGM battery based upon Scott's comments and this experience. Thanks for the feedback.

[scottly]

Doc, were you using a battery tender when not riding the bike?

[CoachDoc]

Doc, were you using a battery tender when not riding the bike?

Occasionally I would hook it up to my tender, usually after not riding the bike for a while, but I didn't use it routinely because I use the 550 pretty regularly. The battery always seemed to maintain its charge pretty well, right up to yesterday. Seems like more of an acute failure than anything else, probably shorted internally, no?

[scottly]

An internal short would read over 2 volts lower than yours did with no load. Your battery has the opposite condition: high internal resistance when under load. I don't like battery tenders, and there have been other reports of short battery life when using them.