Interesting Electrical Anomoly

[k100lt]

Was removing the battery today on the K100LT to do a battery service. I first removed the NEG. lead and happen to notice that my digital clock was still running. That's odd I thought. Normally when you remove the battery ground lead, power is removed from the bike. I whipped out my trusty analog volt/ohm meter and checked for power from the POS term on the battery to a ground lug on the frame. Sure enough I had power. Not a full 12v but pretty close. I then used the battery hold down strap screws as a ground and had power. I had some bare metal spots on the hold down strap itself so removed the strap and used a piece of paper as an insulator between the strap and the case. This time when I checked for power between the POS term on the battery and ground lug, no voltage was present. I then removed the strap and checked for voltage from the top of the battery case to ground and I would get a slight indication of voltage. I wiped down the case checked for voltage again, none indicated. The top of the case was slightly wet before I cleaned it off. Prior to this had no battery issues at all....David

[roy]

Was the top of the battery damp between the positive terminal and the hold down strap. This would allow a slight current path that would operate your clock and probably register voltage on your meter also.

Just my $.02 worth.

[wmubrown]

Prior to this had no battery issues at all....David
I don't quite understand what you are describing. The battery "strap" which was a plate across the top of a K100 was held down with two long bolts to the battery tray. It was all metal, so I don't understand the comment about "bare metal spots". When you remove the negative cable, that breaks the circuit path from the battery positive terminal, to the bike electronics and back to the negative terminal, so everything should shut off. If it does not there is either another power source operating like a battery charger plugged into an aux outlet, or one of those 9V battery to cigarette lighter plug adapters to keep the clocks and radio stations set in a vehicle. Barring that, you still have a path to ground even though the cable is removed. It sounds like the battery strap was in contact with the negative terminal and became the source to ground which is why the paper as an insulator showed no voltage. Once that was removed, there still being power, something else was creating a ground connection - are you sure that wasn't acid you wiped off the battery? If there was enough, and it ran down the side of the battery to the bottom plate, that could provide a weak ground circuit but it's a stretch.
Very strange...

[wmubrown]

Was the top of the battery damp between the positive terminal and the hold down strap. This would allow a slight current path that would operate your clock and probably register voltage on your meter also.

No, what you describe would be a secondary circuit parallel to the clock circuit. Just because there is a circuit between the pos and neg terminals on the battery due to the fluid does not mean the circuit path from the pos terminal, to the clock, and back to the negative terminal would be complete. What we're looking for is what completed the ground circuit so the clock still ran. It's possible the fluid completed the circuit for the clock between the neg terminal and the bike ground (the base the battery sits in) if it was acid, or other mineral rich fluid (distilled water does not conduct electricity). I still think that's a stretch though... more info is needed.

[cjack]

something else was creating a ground connection - are you sure that wasn't acid you wiped off the battery? If there was enough, and it ran down the side of the battery to the bottom plate, that could provide a weak ground circuit but it's a stretch.
Very strange...

The thinking here is that there is a pretty ionic path to ground by the acid residue that collects on the surface of the battery. I think the bare metal spots he refers to are those areas on the metal plate that always get stripped of paint from that acid residue.

[wmubrown]

I think that the thinking here. A pretty ionic path to ground by the acid residue that collects on the surface of the battery. I think the bare metal spots he refers to are those areas on the metal plate that always get stripped of paint from that acid residue.
Must be... I've never considered paint a good insulator, so I see it all as a metal plate, and a conductor, paint or not. At one point, I glued a rubber sheet to the bottom of that plate after putting in a Westco battery and not feeling comfortable with how close it's terminals came to that plate.

[k100lt]

Thanks guys for the excellent feedback on this anomoly!!..The dampness on top of the battery must have been acid. After I removed the hold down strap I could still get a needle fluctuation when I rubbed the top of the battery with the POS lead of my meter and the NEG lead to frame GRND. The strap had several bare spots where the paint had erroded away. (this was on the side that would rest on top of the BAT). After I removed the strap I did a cursory cleaning of the top of the BAT with a paper towel and re-checked with my meter. No more needle fluctuations. I could get some minor fluctuations if I probed the small area between the cell cap and case or in the well of the screwdriver slot on the cap. There were no other sources of external power hooked up to the bike. After I removed the BAT from the bike, I charged it up overnight, cleaned the top with water/bakeing soda, re-painted the hold down strap and insulated the side that rests against the BAT with electrical tape. Re-installed the BAT in the bike and repeated the checks with my meter. No indications of the original problem were found. I suspect it was the strap/acid combo. that provided a ground.

[cjack]

Acid residue on the top of the battery can discharge your battery over time also. So it is a good thing to keep it clean.

[k100lt]

Good tip Jack.. I usually pull the battery out every two months to service it. This is the first time I noticed any dampness on it. In the future I will keep a closer eye on it..