Curious about the Clock
Posted: Fri Feb 03, 2023 6:54 am
It has always been somewhat puzzling to me that BMW would design a clock that acted like a parasitic draw on the battery of so many of their 70's and 80's motorcycles. When I first got into an R100RS years ago I was told by the PO that he would just unplug the clock between rides which seemed somewhat inconvenient considering this meant resetting the clock every ride and providing frequent opportunities to damage the internals, connecters etc. I kept the bike on a tender and didn't think much more about it. Fast forward ten years and I no longer have that RS but I do have a G/S in the garage and it has the accessory clock as well. While going through this bike and refreshing it for service I ponied up for Motobatts fancy new Hybrid tech battery which claims to offer the best of both worlds and provide significantly greater capacity than what is necessary for my old bike. (Probably an unnecessary waste) That said, if I don't ride the bike for a week or so, the clock draws enough current to sufficiently drain the battery to the point where I can no longer start the bike with the electric starter. So I keep the bike on a tender and all is seemingly well.
That brings me back to my initial question and curiosity of what might these designers and engineers have been thinking owners would do with these constant parasitic draws on their batteries? I suppose if these designers assumed that these bikes would be ridden daily or at least several times a week, then I would guess the draw from the clock would likely be insufficient to drain the battery to the point of rendering it incapable of turning over the bike. But aside from that assumption, it strikes me as odd that they wouldn't have designed these clocks to run on watch batteries or some other secondary source of power. Unlike on the RS, the G/S clock harness runs into the headlight bucket and isn't simple to disconnect so it seems that keeping the bike on a tender is the only viable option for me and it certainly doesn't keep me up at night but it just seems like a rather odd design and I wondered if anyone might have some deeper insights to share.
Best!
-Chris
That brings me back to my initial question and curiosity of what might these designers and engineers have been thinking owners would do with these constant parasitic draws on their batteries? I suppose if these designers assumed that these bikes would be ridden daily or at least several times a week, then I would guess the draw from the clock would likely be insufficient to drain the battery to the point of rendering it incapable of turning over the bike. But aside from that assumption, it strikes me as odd that they wouldn't have designed these clocks to run on watch batteries or some other secondary source of power. Unlike on the RS, the G/S clock harness runs into the headlight bucket and isn't simple to disconnect so it seems that keeping the bike on a tender is the only viable option for me and it certainly doesn't keep me up at night but it just seems like a rather odd design and I wondered if anyone might have some deeper insights to share.
Best!
-Chris