Battery tender causes buzzing in 1150RT

[OfficerImpersonator]

My '02 1150RT-P has a plethora of BMW accessory electrical sockets. One on the dash and two on the left side just below the seat. If I plug my BMW-brand battery tender into either the socket on the dash or the rear of the two on the left side, a buzzing sound soon emanates from beneath the seat - I presume from one of the relays in the electrical box under the seat.

If I plug the tender into the forward of the two under the seat sockets, all is fine.

The buzzing sound is loud enough that the first time I heard it I was inside the house while the bike was in the garage - about 30 feet away and through a wall!

I presume that the socket on the dash is directly connected to the second battery, but the charger should still be able to "tend" the auxilliary battery.

There are no other problems with the bike, and there don't seem to be any consequences caused by the buzz. Any idea what's going on?

[Seeker]

Second Battery?

[OfficerImpersonator]

RT-Ps have two batteries - one in the conventional location, and one in the compartment on the left side of the fairing, where "regular" RTs have either the radio or the glove box/cubby hole thingy.

Cop radios, cop sirens, cop lights, and cop oil cooling fans require lots of juice.

[OfficerImpersonator]

Bump

[OfficerImpersonator]

Am I correct in assuming that no one has ever had a battery tender cause their bike to exhibit a buzzing sound from the electrical box?

[Motor31]

No RTP or battery tender here, so can't help. Sorry.

Have you tried isolating one battery from the other and seeing if the buzzing continues?

[PGlaves]

I have had my hands on only a few RT-P bikes, but have to say that I haven't yet encountered one that didn't have its wiring seriously jacked-up (damaged) by a police technician or someone willy-nilly stripping verboten police equipment off the bike prior to its sale to the public.

That said, a buzzing sound is usually a relay. I'm not at all sure how BMW (or somebody else) might have connected those two batteries. If that were my bike I'd disconnect the auxiliary battery temporarily. Then I check each outlet for power so I could tell which outlet was connected to which battery.

Then I'd try my charger on just an outlet wired to the main battery. Check for buzzing. I would then reconnect the aux battery and put the charger on it with just clips at the posts. In this process you ought to get some strong clues as to how things are wired together. Them aim for that wiring.

[mrich12000]

:fight Sounds like:lurk the Rectifier is bad also the half wave filter capacitor is damaged:bottle , allowing A/C 60 hrz into the battery sugest you replace it as it isn't doing it's job. Could hurt some electronics as well.:banghead


Mike Richard
VE3CEH

:type Hope to see you all in Nova Scotia:buds :bolt