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Thread: Battery Tender Hook-up

  1. #1

    Battery Tender Hook-up

    I may be close to maxing out my quota of posts as a newbie, I promise to throttle back once I have the car fully set up. I'm about to install a permanent hookup for a Battery Tender in the trunk (don't want to use alligator clips). My plan is to connect the positive lead to the positive battery post clamp, and the negative lead to the grounding post under the carpet on the right side of the trunk, similar to the setup "2112" used in the archived posting "new charger" in Tips, Tricks, and Useful Bits.

    Two questions- is this the generally preferred set-up? Assuming it is, I have a concern about disconnecting the battery during installation. One hears horror stories about problems resulting from total loss of power, is this a legitimate concern? If so, if I were to temporarily connect the battery tender at the front of the car with alligator clips using the under-hood positive connection point and the grounding bolt on the drivers side inner fender, would this keep power to the car during the disconnection of the battery? Would this avoid problems or create new ones?

    Unfortunately, we had our first snow flurries here in the northeast this morning, and the Red Zed is going into winter storage soon. Luckily, I was able to get fully acquainted with the car on a pleasant 630 miles two day drive from NC to NJ after purchasing it last week. Ran like a champ.

    Bill

  2. #2
    I haven't installed my battery hook up in the trunk yet, it's still in the cupboard awaiting the perfect day :-)

    I bought a kit from CTek that bolts to the battery, and has a neat little fishtail plug that goes right into the charger cable. I'll post some pix when I do get around to installing it.

    However I have swapped batteries a few times and not had any problems, just make sure that everything is turned off before the disconnect and you should be all good.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  3. #3
    Sport Button On - DSC Off Kevin's Avatar
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    I've always charged through the cigarette lighter with the Z8 and so far so good. However the SLS I just got came prewired from MB with a trickle charger 'port' in the trunk. It uses a sort of Magnetic attachment which I've never seen on any other car.
    2003 Z8 Silver/Black AH62031 (Sold)

  4. #4
    Z8 Madness Z-acht's Avatar
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    I use the same setup for a year now as Andrew has installed and it works fine for me. CTEK says that it has to be ventilated so I leave the lid open.
    Ton
    1 of the 71 original Dutch sold cars (jetblack/red)

  5. #5
    I use both the BMW (deltran) and porsche (c-tek) battery tenders through the cigarette lighter. From my perspective it is more important to maintain your battery in the Z8 than the route used, via the lighter or directly to the battery.
    Last edited by EDEZ8; November 13th 2013 at 14:53. Reason: Double post
    My Best,

    Ed

    2002 Z8 Jet Black//Sport Red
    2012 SLS AMG Obsidian Black/Classic Red

  6. #6
    Z8Mania
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    The Z8 Cig lighter is always on so it works on the Z8. Thats not so on most newer cars. I think its preferable to go direct to the battery. You don't need to disconnect the battery to hook up the little eyelets. There are places on the terminals you can just unscrew a nut and put the eyelet on it and then screw the nut back. In the USA the Ctek instructions don't mention keeping the battery area open/ ventilated. I just close the trunk and its been fine. Been using this for years now.... on several cars........

  7. #7
    Hi Jerry,

    I see the two nuts on top of each battery clamp that I assume you are referencing. Is it OK to attach the positive AND negative tender leads to their respective clamps, or does the negative lead need to be grounded to the car elsewhere?

    As always, thanks for your help!

    Best,

    Bill

  8. #8
    Z8Mania
    Guest
    Hi Bill, that's how I've done it on several cars with no ill affects (negative lead to the negative port on the battery).

  9. #9
    On the release of hydrogen gas from the battery during the charge cycle, there's a vent tube (see picture) that allows for the gas to be passed to the underside of the car. Although its permeable to gases, I'll still remove the car cover from the backend of the car when on the trickle charger.

    Name:  battery vent tube.jpg
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    My Best,

    Ed

    2002 Z8 Jet Black//Sport Red
    2012 SLS AMG Obsidian Black/Classic Red

  10. #10
    Got the Battery Tender hooked up with no problems. Also swapped out the trunk lid struts which were getting weak. Went through NJ inspection this afternoon without a hitch- good day for the Red Zed!

    Thanks to everyone for the tips on hooking up the tender. I also used an archived thread to facilitate the strut changeover-one of those things that is very easy to do, so long as you know the trick for getting the old ones off.

    Bill

  11. #11
    Team Z8 zed8's Avatar
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    Hi boomster, I`ve been charging the battery with a direct connection to it for years. There is cable with a connector on one end and little eyelets on the other end. Eyelets are connected to the battery terminals. When ever I want to connect the car to the charger I just plug the male and female connectors. I leave the trickle charger out of the car.
    Hattat

    AF77768 Topasblau / Schwarz

    PP installed
    Motorsport 20" style 101 wheels
    Eisenmann catback
    Supersprint headers
    CDV removed
    Quaife LSD
    3.64 gearing

  12. #12
    Z8Mania
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    Interesting Ed. Ive had my cars connected to tenders for years and no manufacturer of either car nor tender has ever mentioned that...

    Bill- thats great news. Well done!

  13. #13
    Z8 Madness Z-acht's Avatar
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    Here is the connection Ed mentions I think



    The eyelets are glued to the battery ( below) and from there they go to a female connector and the tender has a male connector...don't have to explain mote I think
    Ton
    1 of the 71 original Dutch sold cars (jetblack/red)

  14. #14
    That is essentially the same setup I used-I used the nuts on top of the battery post clamps (positive and negative) to connect the eyelets. I never disconnected the battery from the car, so no settings were lost and no concern about power surges damaging something. I run the lead from the Battery Tender in through the trunk lid, which of course is open, the trunk lights go out after a few minutes. I have a Battery Tender on my Harley, which has given me long battery life, and I am thinking about hooking up my daily-driver Boxster, which sits in the garage a fair amount when my wife and I are at our home in Vermont.

  15. #15
    Z8 Madness Z-acht's Avatar
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    A picture says a thousand words
    Ton
    1 of the 71 original Dutch sold cars (jetblack/red)

  16. #16
    Z8Mania
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    Ton, do you really mean "glued" as in held on to the battery terminal via glue / some kind of bonding agent? I've never seen that if that is the case. I've done mine the way Bill describes to connect the eyelets.

  17. #17
    Z8 Madness Z-acht's Avatar
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    They said it was glued with cyanoacrylate glue.
    Ton
    1 of the 71 original Dutch sold cars (jetblack/red)

  18. #18
    Z8Mania
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    I don't know what that is but it sounds fancy I just used the small screws.

  19. #19
    Z8 Madness Z-acht's Avatar
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    I will check it this week when I am in the workshop
    Ton
    1 of the 71 original Dutch sold cars (jetblack/red)

  20. #20
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    I would like to buy a trickle charger for my car and think the one that connects to the cigarette lighter is easiest. May I get the actual brand and model? Is it as simple as plugging into an outlet and plugging into the cigarette lighter? Thanks.

  21. #21
    Yes, it is, some advise against it, but that's what I've been doing for twelve years. I'm currently using the C-tek 7002, I bought it on Amazon. The OEM unit is a BMW badged unit made by Deltrans, it can be found on Amazon too, but if you want the BMW badging you have to go to your local dealer or as BMW parts specialist.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  22. #22
    Z8Mania
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    I think its better to go straight to the battery but you can go to the cigarette lighter on the Z8. On newer BMW's the car's onboard systems will shut down the cigarette lighter circuit after a few minutes.

  23. #23
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    Very helpful! Thank you for sharing.

  24. #24
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    if you connect directly to the battery, or use the under hood jump starting terminals, how do you get the under-hood lights (or trunk lights) to go out?

    thanks

  25. #25
    Z8 Madness Z-acht's Avatar
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    Quote Originally Posted by mhunger View Post
    if you connect directly to the battery, or use the under hood jump starting terminals, how do you get the under-hood lights (or trunk lights) to go out?

    thanks
    They extinguish after 10/15 minutes
    Ton
    1 of the 71 original Dutch sold cars (jetblack/red)

  26. #26
    Mine is hooked up directly to the battery in the trunk. After a short time (10-15 minutes) the lights go off, even with the trunk lid open. I would imagine the engine hood would work the same way.

    Good luck,

    Bill

  27. #27
    Z8Mania
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    You can also close the trunk. The weather seal will temporarily deform ever so slightly and the wire is negligible. Theres a natural easy point to run it out above the light cluster. Even though Ive been assured the weather seal won't be harmed, I change the location I run the wire out of each time...

  28. #28
    Z8 Madness Z-acht's Avatar
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    I use the Ctek and the instruction manual says the battery should be well ventilated while loaded so that is why I leave the trunk open.
    Ton
    1 of the 71 original Dutch sold cars (jetblack/red)

  29. #29
    Z8Mania
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    We've had this discussion before, I have several CTek tenders, no where does it say this in their US manuals so I too am just following instructions...........

  30. #30
    Z8 Madness Z-acht's Avatar
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    So many countries, so many regulations
    Ton
    1 of the 71 original Dutch sold cars (jetblack/red)

  31. #31
    Our batteries have that breather tube that comes out of the side, so that ventilates them. That said I always leave my trunk, hood, soft top and doors open to increase the seals life, this was a tip from The Club and I've always stuck to it.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  32. #32
    Z8 Madness Z-acht's Avatar
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    Our batteries have that breather tube that comes out of the side
    Did not know that, thanks for the information!
    Ton
    1 of the 71 original Dutch sold cars (jetblack/red)

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