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k1200LT electrical problem

2K views 2 replies 3 participants last post by  jzeiler 
#1 ·
About 4 months ago I was not able to ride my bike every day, When I let it set for more than three days it would not start.
With the ignition off when I connect the battery tender to the battery leads I get an arch from either side of the battery.
The Battery is a BMW purchased in Feb. I took it into the dealer and to have it tested. The BMW official meter said it is fine. Before I reconnected the battery I checked all that visible wires around the seat area, I did find that the grounds wire had burn through on a small area of the lead. I taped it off. I hooked up my charger with the ignition off still got arch’s.
I charged the battery fully in three hours. She will start up great for 6 hours and then she won't even crank over. I was out riding last month stopped for 10 minutes and the bike would only click when I tried to start it
Something must be going to ground to bleed off the battery even with the ignition off. I called and discussed it with the dealer. I asked if the BMW computer would locate the problem and he said no that it did not isolate problems in harnesses or relays.
Does a normal guy with limited skills have ANY chance of fixing this himself without the normal $1K trip to the dealer?
Sadly I love this bike like my first wife. The ride is great but I just refuse to sign the papers and walk away! Ha
Lost dazed and confused.
 
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#2 ·
Pull a battery terminal and install an amp meter in series, or use an inductive meter and leave the cable on.
Start pulling fuses until the draw goes away, I don't know the normal amp draw for your bike, but it should be in the milliamp range.
When you loose the draw, check the fuse location to see what components use it, then put the fuse in and start isolating them one at a time.

There's more but start with this.
 
#3 ·
Given your skills and your available test equipment a good test would be to charge the battery up and then go for a drive. When you get back remove the negative terminal(s) from the battery. There should be only one if all is stock. Then just hook it back up next time you want to ride. There will be arc's as you call them when you do this and that is normal. If the battery does not start the bike then the battery is bad. If it does start the bike then you have something pulling the battery down.

Now is when having an ammeter would be handy. If you have a Harbor Freight they usually have multimeters for less than $10. Once you get one you can then track down what is pulling the battery down. Place the meter on the highest "amp" scale and connect it between the negative lead and the battery negative terminal. After the initial "arc" the meter sould only read about 5 milliamps of current. If it does not then start unhooking things added to the bike and then pulling fuses like New2rt suggested.

Also it is a good idea to always shut down the radio before turning the key to off. Then turn the key to "lock" to shut down all accessory driven items.
 
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