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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: Kchop on September 29, 2025, 11:34:30 AM

Title: K75s Battery draining
Post by: Kchop on September 29, 2025, 11:34:30 AM
Help. scheduled for a long ride this weekend. 93 k 75s

What else besides the alternator can be draining my battery?

Battery is new.
Alternator tested good.(previously)
Voltage regulator is new w/brushes.
No parasitic draw I can measure.

Possible the stator went bad?
Do k bikes have a separate/additional rectifier?
Title: Re: K75s Battery draining
Post by: frankenduck on September 29, 2025, 02:26:22 PM
The only drain should be the LCD clock in the cluster but that's a tiny drain.
Title: Re: K75s Battery draining
Post by: Laitch on September 29, 2025, 04:33:27 PM
How long has your new battery been installed? How much have you run the engine every day since the battery was installed? How quickly does the battery become discharged?
Title: Re: K75s Battery draining
Post by: Kaos on September 29, 2025, 05:28:21 PM
And are the mass connectors, connected properly and clean and is your alternator connected to your Battery?
And did you measure charge from the alternator while your bike was running?
Also is the chargebulb lid when idle/low rpm ?
Title: Re: K75s Battery draining
Post by: Kchop on October 08, 2025, 10:22:07 AM
Hey, Just wanted to thank everyone on here. @kaos @Frankenduck @Laitch and anyone else offering suggestions. Electrical problems all figured out, gas tank sealed from the inside.. holding so far. Motor, Gear and final drive oils changed. Much of the work done by me. Throttle body and synching done by excellent former British airplane mechanic.

Just got back from ride, 800 miles in three days. All conditions experienced; highway, two-lane, dirt, loose gravel, etc.
have to say I'm proud of the k bike.. handled everything with class

cheers
Title: Re: K75s Battery draining
Post by: Laitch on October 08, 2025, 03:29:56 PM
Electrical problems all figured out, . . .
Which problems were those, and what was causing them?
Title: Re: K75s Battery draining
Post by: Kchop on October 13, 2025, 11:01:23 AM
Hey, well..I bought a less expensive battery about a year ago, was riding bike around in anticipation of a this longer ride. Apparently this battery TOTALLY  died, as in irrecoverable with battery tender. So, I took older odyssey battery I had and started with that to discover why. In the 'dying' process it blew fuse 3 and 6 somehow. After doing all the diagnostics recommended here, its seems it was one bad phase from stator.
Title: Re: K75s Battery draining
Post by: Laitch on October 13, 2025, 11:26:50 AM
Thanks for the update.

Tenders usually can't restore discharged batteries, their purpose is to prevent them from discharging, but technology continues to advance. Did you replace the stator yourself, contract it out, or replace the entire alternator and be done with it?
Title: Re: K75s Battery draining
Post by: Kchop on October 13, 2025, 12:13:17 PM
I found an ex British airplane mechanic about an hour or so from me. He admitted that he wasn't really a bmw expert. I have to say because of this forum etc, I've done and learned so much on my k bike in the last year its crazy. we pirated the stator from the a used alternator. Not sure fully what he all did on the bike (conversation this week), but it's running better than it has in like ten years.

I usually ride slow, look around .daydream, etc.

I found myself riding with this group at like 85mph and kind of smiling..
Title: Re: K75s Battery draining
Post by: Laitch on October 13, 2025, 12:22:43 PM
 112350
Title: Re: K75s Battery draining
Post by: frankenduck on October 13, 2025, 02:03:13 PM
Thanks for the update.

Tenders usually can't restore discharged batteries, their purpose is to prevent them from discharging, but technology continues to advance. Did you replace the stator yourself, contract it out, or replace the entire alternator and be done with it?

I have two tenders that supposedly desulfate/repair batteries:

4 amp: https://www.topdon.us/products/tornado4000

1 amp: https://no.co/genius1
Title: Re: K75s Battery draining
Post by: Laitch on October 15, 2025, 02:49:23 PM
supposedly desulfate/repair batteries: . . .
Now there's a ringing endorsement.  :laughing4-giggles: