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Thread: '91 K75RT where to hook my battery tender to ?

  1. #1

    '91 K75RT where to hook my battery tender to ?

    Here in Canada it's getting a bit cooler these days ,and I got a battery tender to have on my 1991 K75 RT . I still plan on riding for a few days off and on , and don't want to remove the seat each time I return home . I only have had this bike since August ,and despite having 3 service manuals I'm not sure if there's a more simple way to have my battery tender charging my battery .
    Any advise will be appreciated .

  2. #2
    #13338 PGlaves's Avatar
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    Quote Originally Posted by xcaret View Post
    Here in Canada it's getting a bit cooler these days ,and I got a battery tender to have on my 1991 K75 RT . I still plan on riding for a few days off and on , and don't want to remove the seat each time I return home . I only have had this bike since August ,and despite having 3 service manuals I'm not sure if there's a more simple way to have my battery tender charging my battery .
    Any advise will be appreciated .
    You need to attach a fused two-pole plug to the battery with the connector accessible. Then you need to equip the battery charger with the mating two-pole connector. At the battery side the female connection needs to be +12v and the male connection needs to be ground. And at the battery charger the positive +12v connector needs to be the male connector and the negative ground connector needs to be the female one.

    Or, if you have the BMW accessory socket on the bike then you can just attach a mating plug that fits the socket. The plug can be obtained from Powerlet and a number of other vendors.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://web.bigbend.net/~glaves/

  3. #3
    Debbie's Servant Lee's Avatar
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    Quote Originally Posted by PGlaves View Post
    Or, if you have the BMW accessory socket on the bike then you can just attach a mating plug that fits the socket. The plug can be obtained from Powerlet and a number of other vendors.
    Here's the plug Paul mentioned.
    https://www.amazon.com/Powerlet-PAC-...5976917&sr=8-4
    Lee
    2022 R1250RS
    MOA # 30878
    Past BMW Bikes: 2016 R1200RS, 2011 K1300S, 2003 K1200RS, 1991 K75S, 1987 K75T, 1984 R100RT

  4. #4
    Fortis Fortuna Adiuvat Omega Man's Avatar
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    Direct to the battery gives one great versatility.



    https://www.batterytender.com/accessories

    The pig-tails are available everywhere.

    OM
    "You can do good or you can do well. Sooner or later they make you choose." MI5
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  5. #5
    Debbie's Servant Lee's Avatar
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    I thought the accessory outlet was standard on all K75 bikes.
    The accessory outlet is wired direct to the battery.
    Lee
    2022 R1250RS
    MOA # 30878
    Past BMW Bikes: 2016 R1200RS, 2011 K1300S, 2003 K1200RS, 1991 K75S, 1987 K75T, 1984 R100RT

  6. #6
    Registered User 6322's Avatar
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    The accessory plugs, either the factory BMW plug or the one Paul mentioned, have a lot of uses. Besides the battery charger, I plug my heated vest in there as well as my tire pump as needed. On my hack, a K100RS, my wife also uses a heated car blanket that plugs into a port in the boat. Be sure to wire it per Paulís direction and include a fuse on the positive side as it comes off of the battery.
    Gary Phillips - #6322
    Wildland Firefighter, Retired, Riggins, ID
    Heartland Moto Locos BMW Riders
    '77 R100/7 Dirt Hack, '83 R80ST, '85 K100RS w/EML, '93 K1100LT, '00 R1100RS

  7. #7
    Quote Originally Posted by Lee View Post
    I thought the accessory outlet was standard on all K75 bikes.
    The accessory outlet is wired direct to the battery.
    My bike might have one, but being I only has it for 2 months I may have overlooked it . What is it's location?

  8. #8
    Debbie's Servant Lee's Avatar
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    Quote Originally Posted by xcaret View Post
    My bike might have one, but being I only has it for 2 months I may have overlooked it . What is it's location?
    Look on the left side of the bike below the seat. It has a round springed cover.

    9359_0_1_4_k 75 rt_Clot-s Bike.jpg
    Lee
    2022 R1250RS
    MOA # 30878
    Past BMW Bikes: 2016 R1200RS, 2011 K1300S, 2003 K1200RS, 1991 K75S, 1987 K75T, 1984 R100RT

  9. #9
    3 Red Bricks
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    scaret,

    If your charger is a Battery Tender by Deltran, the normal cable for charging is:

    https://www.batterytender.com/Ring-Terminal-Harness

    This cable should have been included with your charger (along with another cable that has aligator clips). The above cable is designed to be permanantly hooked up to the battery terminals by it's ring terminals. It is 24" long and can be left coiled up behind the left battery cover for quick access. It has an inline 7.5 amp fuse and an SAE flat two prong connector with cover on the end (just like your charger).

    Check to see if the previous owner has already installed one. Pull the left battery cover and look at the positive terminal. If it's there, the cable will have a red band around where the wire connects to the ring terminal. Follow that wire away from the battery, past the fuse, to the SAE connector. That would be where you plug the Battery Tender in to charge the battery. You can also plug things like air pumps, or heated gear into it as long as it draws less than 7 amps.


    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  10. #10
    Gerard jagarra's Avatar
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    Battery Tenders usually come with 2 harnesses, one with the large clamps and another to attach to the battery bolts holding the cables to the battery post. The Hella Din socket built into the bike may be fused through your panel so it has limited current capabilities, I have found using the pigtail for the Battery tender to power an air compressor works great as the pigtail has a higher rated fuse in the circuit. When I pulled off my cover over the coils that has the Hella din socket it wasn't hooked up to the battery, maybe worth a look to see if it is hooked to a voltage source.
    1994 R1100RS-(5/93)-,1974 R90/6 built 9/73,--1987 K75S,--1964 Triumph T100--1986 Honda XL600R

  11. #11

    Don't use the factory plug outlet unless it's wired directly to the battery!

    Originally, the factory plugs when thru the bike's electronics and BMW sold a special charger approved to not fry the electronics. Many dealers got in the habit of re-connecting them directly to the battery so any charger could be used. Make sure yours is connected directly to the battery before using it to charge the battery.

  12. #12
    Quote Originally Posted by Lee View Post
    Thanks I think my battery tender came with something like that.. I'll check when I get back.

  13. #13

    Thanks everyone ,

    I just looked and my bike has the factory power outlet . I would have never noticed it if I didn't get the photo from you guys .. Thanks for all your advise ..
    ..

  14. #14
    3 Red Bricks
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    Quote Originally Posted by xcaret View Post
    I just looked and my bike has the factory power outlet . I would have never noticed it if I didn't get the photo from you guys .. Thanks for all your advise ..
    ..
    I believe that the RTs also came with a second power outlet on the dash or panel under the windscreen.




    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  15. #15
    Yes my battery tender came with the connections you guys showed . It has 75 amp fuse , Is that ok ?

    I removed the storage tray and easily connected the leads of the battery tender to the battery . That's so cool ..

    I notice I'm missing a cover that goes over the fuel control unit .. I hope that's ok ,it's hidden behind the side cover .. That was much easier than what I had envisioned after looking at my service manuals
    Thanks for all your help

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