Seemingly unsolveable problem - HELP

[beemer01]

My son has a 2011 650GS thumper, but the battery continually goes dead when parked for more than a couple of days. BMW Manhattan has soaked him for well over $1200 for new battery (to replace a six month old battery) shop time and for a new rectifier. The bike has been back three times.

As the bike is parked on the street, keeping it on a charger isn't an option.

Their techs are obviously incapable of solving an electrical problem. This is a relatively simple bike with added fog lights and a kill switch that interrupts the starter circuit. (We're not talking an '86 Land Rover for heaven's sake.)

Does anyone have any ideas? HELP!

 

[dbrick]

This isn't rocket science, and I'm surprised the dealer is flummoxed. If the battery is OK, then there's a circuit or connection or device somewhere that's allowing current to flow even when the ignition is off (and, presumably, the added-on kill switch is opened).

I'd start by making sure that the only two wires connected to the battery are its + and - cables. Then open the kill switch, as he'd do when parking it on the street. With that switch open, no current should be flowing through the bike - there should be infinite resistance between the battery + cable and the battery - cable.

If there isn't infinite resistance, then the kill switch isn't working, or something is connected somewhere that shouldn't be, or some combination. While it's possible that the bike's residual consumer of electricity (a clock, perhaps) is broken and uses more juice than it should, opening the kill switch should (if the switch is OK) make any flow of electricity impossible.

If there is infinite resistance, then I don't see how the battery could go flat...other than it's a bad battery. And bad batteries right out the box are not unknown.

Report back, and let us know what he finds.

 

[Omega Man]

I'm not familiar with the specific bike. That said, take one fuse at a time out unti the problem circuit is identified. Yeah it's a bit of a slow process but will usually help.
OM

 

[mikegalbicka]

$1200 for a battery and rectifier! I wouldn't be going back there.

 

[wezul]

'86 Land Rover, ha! At least you are keeping your sense of humor (humour?). That $1200 dollar bill though, I am assuming this is not Manhattan, Kansas
I got nothing for you Bryan but best wishes!

 

[pglaves]

$1200 for a battery and rectifier! I wouldn't be going back there.

He said "Manhattan".

 

[pglaves]

T
I'd start by making sure that the only two wires connected to the battery are its + and - cables. Then open the kill switch, as he'd do when parking it on the street. With that switch open, no current should be flowing through the bike - there should be infinite resistance between the battery + cable and the battery - cable.

If there isn't infinite resistance, then the kill switch isn't working, or something is connected somewhere that shouldn't be, or some combination.

I want to add: After making sure there are only the two original cables at the bayyery - then, disconnect both battery cables or at least one of them. Then with the auxiliary switch in the open (off) position use an ohm meter to read the resistance from one cable end to the other cable end. This should read totally open or infinite resistance.

 

[dbrick]

Thanks, Paul, that's what I was thinking but didn't write well.

 

[beemer01]

He may have found the problem -

He and his passenger recently left the bike parked and locked up for a while. They returned to the bike after a Soda - and they noticed that the headlight was on - even though the ignition was off... key in pocket.

I surmise that the headlamp relay is faulty? if so, where is it located? Anyone ever seen this before?

 

[grendellion]

He may be leaving the parking light on. According the manual key position 3 locks the fork and turns on the parking light and you can remove the key. If you turn the key further to position 4 the parking light turns off.