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Thread: Do Not Connect Battery Charger Directly to Battery ?!?

  1. #1

    Do Not Connect Battery Charger Directly to Battery ?!?

    My new to me F700GS came with an sae 12V plug attached directly to the battery, for connecting to a trickle charger that was also included. Great!

    Or not?

    Reading through the owner’s manual, it clearly states to only attach a trickle charger via the on board 12V Hella style plug in the dash. It says NOT to connect a charger directly to the battery, due to risk of possible electrical damage.

    I am a believer in following the owners manual, barring convincing evidence to the contrary. What is the collective wisdom on this topic?

  2. #2
    I have connected directly to the battery on 26 different BMWs which we have owned over the years. On Oilhead motorcycles BMW even provided a convenient post/lug connected directly to the starter hot lead for the purpose of either charging or jump starting. If BMW is now constructing the electronics on the F700 so fragile that connecting to the battery would be a worry I would run from the model and brand as fast as I can.

    I am sure there is some disaster scenario where applying improper voltage, or creating some type of short circuit might damage something. That said, I believe that in applying a 12v (nominal) charger to a 12v battery, for most people the human brain is as good as some shutoff gizmo BMW has installed.

    However, if you have a charger with the correct DIN plug, then there is really no downside to doing it their way even if it is a crock of male bovine excrement.
    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
    Fortis Fortuna Adiuvat Omega Man's Avatar
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    Quote Originally Posted by vark View Post
    My new to me F700GS came with an sae 12V plug attached directly to the battery, for connecting to a trickle charger that was also included. Great!

    Or not?

    Reading through the owner’s manual, it clearly states to only attach a trickle charger via the on board 12V Hella style plug in the dash. It says NOT to connect a charger directly to the battery, due to risk of possible electrical damage.

    I am a believer in following the owners manual, barring convincing evidence to the contrary. What is the collective wisdom on this topic?
    That increases sales of that Hella plug!

    My guess is that particular instruction is to-
    1) Keep non-factory wiring from being installed on the bike..... possibly causing a warranty issue.
    2) Easier for BMW to explain that when using a battery tender, make sure connections are good, solid and correct.
    OM
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  4. #4
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    Actually BMW'S caution has to do with the advent of "smart" chargers that have a desulphation mode. If the charger decides the battery is sulphated it tries to recondion it by hitting it with a series of high voltage pulses. Herein lies the risk to the bike's electronics. Any modern BMW would have such electronics. Out of an abundance of caution BMW tells you to remove the battery from the bike to charge it with other than its charger. BMW cannot rely on bike owners to make such distinctions. Most riders these days are "appliance riders".

    That being said the likelihood of damage may be low but the safe thing to do is either don't use a charger that has a desulphation mode or disable desulphation. I charge through Powerlet receptacles wired direct to the battery with desulphation disabled.

    Sent from my SM-T813 using Tapatalk

  5. #5
    Quote Originally Posted by PGlaves View Post
    .... If BMW is now constructing the electronics on the F700 so fragile that connecting to the battery would be a worry I would run from the model and brand as fast as I can...

    What does the Owner’s manual for your pair of G310GS bikes say on this subject?

    .

  6. #6
    Quote Originally Posted by RadioFlyer View Post
    Actually BMW'S caution has to do with the advent of "smart" chargers that have a desulphation mode. If the charger decides the battery is sulphated it tries to recondion it by hitting it with a series of high voltage pulses. Herein lies the risk to the bike's electronics. Any modern BMW would have such electronics. Out of an abundance of caution BMW tells you to remove the battery from the bike to charge it with other than its charger. BMW cannot rely on bike owners to make such distinctions. Most riders these days are "appliance riders".

    That being said the likelihood of damage may be low but the safe thing to do is either don't use a charger that has a desulphation mode or disable desulphation. I charge through Powerlet receptacles wired direct to the battery with desulphation disabled.
    That’s what my manual says to do, i.e. remove battery from bike when connecting chargers directly to it. But that would be a major hassle for anyone just wanting to trickle charge.

    Near as I can tell this bike has been hard-wire trickle charged for a long time, and may even have come pre-wired that way from the dealership.

    .

  7. #7
    Registered User ExGMan's Avatar
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    Quote Originally Posted by vark View Post

    Near as I can tell this bike has been hard-wire trickle charged for a long time, and may even have come pre-wired that way from the dealership.

    .
    My 2015 RT had an SAE plug installed by the BMW dealer from which I bought the bike. The dealer used it when it was in their demo inventory, and I've been using it ever since. Whenever I'm not on a trip, or riding locally it's connected to an Optimate-4 via the SAE plug.
    John Gamel - BMW MOA Consumer Liaison
    2015 Ebony Metallic R1200RT
    MOA #153274
    "We have met the enemy, and he is us." Pogo/via Walt Kelly

  8. #8
    Quote Originally Posted by ExGMan View Post
    My 2015 RT had an SAE plug installed by the BMW dealer from which I bought the bike. The dealer used it when it was in their demo inventory, and I've been using it ever since. Whenever I'm not on a trip, or riding locally it's connected to an Optimate-4 via the SAE plug.
    I’m also curious, what does the owner’s manual for your 2015RT say on this subject?

  9. #9
    Interesting discussion. Following
    The lion does not even bother to turn his head when he hears the small dog barking.

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  10. #10
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    At least my last five BMW models have come from three different dealers and they've all come with pigtail already attached by dealer. If prior one haven't I've added it. Never a problem. VARK, if you go to BMW's site, you can review just about every owners manual.

    https://www.bmw-motorrad.com/en/serv...er-manual.html
    MOA #46783

  11. #11
    SURVIVOR akbeemer's Avatar
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    I've had a pigtail on every bike I've owned, regardless of brand. Never an issue.
    Kevin Huddy
    The Outpost, Silver City, Montana

  12. #12
    3 Red Bricks
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    RadioFlyer's explanation seems the most plausible. It's probably a BMW CYA.

    But, if you use the wrong charger and fry something, you have been warned. Like he said, all chargers are not alike. Should not be a problem with basic chargers or BatteryTenders.

    I've used a BatteryTender float charger on my wife's F700GS, through a SAE pigtail direct to the battery, for 6 years now (she doesn't ride much any more).

    The BEST charger is frequent long rides!






    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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  13. #13
    Registered User ExGMan's Avatar
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    Quote Originally Posted by vark View Post
    I’m also curious, what does the owner’s manual for your 2015RT say on this subject?
    Here is what the manual for my RT says:

    Battery
    Maintenance instructions
    Correct battery maintenance
    combined with proper charging
    and storage procedures extends
    the battery's service life, and is
    also required for warranty claims.
    Compliance with the points below
    is important in order to maximize
    battery life:

    Keep the surface of the battery
    clean and dry
    Do not open the battery
    Do not top up with water
    Be sure to read and comply
    with the instructions for charging
    the battery on the following
    pages
    Do not turn the battery upside
    down.
    If the battery is not disconnected,
    the onboard electronics
    (clock etc.) will drain the
    battery. This can cause the battery
    to run flat. If this happens,
    warranty claims will not be accepted.
    During driving breaks of more
    than 4 weeks, a trickle-charger
    should be connected to the
    battery.

    BMW Motorrad has developed
    a trickle-charger specially
    designed for compatibility
    with the electronics of your motorcycle.
    Using this charger, you
    can keep the battery charged
    during long periods when the
    motorcycle is not being used
    without having to disconnect the
    battery from the motorcycle's
    onboard systems. Additional information
    is available at your authorized
    BMW Motorrad retailer.

    Charge connected battery

    Charging the connected
    battery directly at the battery
    terminals can damage the
    motorcycle electronics.
    To charge the battery via the
    battery terminals, disconnect the
    battery first.
    If the multifunction display
    and indicator lamps fail to
    light up when you switch on the
    ignition, the battery is completely
    discharged (battery voltage below
    9 V). Attempts to recharge
    a completely discharged battery
    through the onboard power
    socket can damage the motorcycle's
    electronic systems.

    Always charge a completely
    drained battery directly at the
    terminals of the disconnected
    battery.

    Charging the battery via
    the onboard socket is only
    possible with suitable chargers.
    Unsuitable chargers can result in
    damage to the motorcycle electronics.
    Use suitable BMW chargers.
    The correct charger is available
    through your authorized
    BMW Motorrad retailer.

    Charge disconnected battery
    via onboard socket.

    The motorcycle's onboard
    electronics know when the
    battery is fully charged. The
    onboard socket is switched off
    when this happens.
    Comply with operating instructions
    of charger.
    If you are unable to
    charge the battery via
    the onboard socket, you
    may be using a charger that
    is not compatible with your
    motorcycle's electronics. In
    this case, charge the battery
    directly at the terminals of the
    disconnected battery.


    Here is what my dealer said: "Attach the battery maintainer to the SAE plug when you're not riding."

    My experience: Two RTs, a 2008 and a 2015...total riding 10 years, about 100K miles both with batteries maintained by Optimate-4s. No problems with batteries or bike electronics.
    John Gamel - BMW MOA Consumer Liaison
    2015 Ebony Metallic R1200RT
    MOA #153274
    "We have met the enemy, and he is us." Pogo/via Walt Kelly

  14. #14
    Quote Originally Posted by vark View Post
    What does the Owner’s manual for your pair of G310GS bikes say on this subject?

    .
    It just says disconnect the battery before charging. It doesn't have any special electronic port. So did the manual for my K75 in 1986. BMW has said this for a very long time with absolutely no explanation as to why. They have also urged owners to buy their very own super duper BMW Roundel emblazoned chargers too, ever since they installed Gel batteries in Oilheads. Those old originals are going for north of $150 now on ebay.

    The caution about de-sulfating chargers is excellent advice. Wouldn't it be nice if instead of telling me I should remove the fuel tank to access and disconnect the battery to auto maintain the battery on my R1150R (it doesn't have a whizbang electronic body guard either) they just in big bold letters said Do not use a de-sulphating charger if the battery is installed in the bike.

    When it comes to technical things I admire honest explanations and not chicanery. Others, I am sure, don't care, but I do.
    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/

  15. #15
    Quote Originally Posted by ExGMan View Post
    Here is what the manual for my RT says:....


    Here is what my dealer said: "Attach the battery maintainer to the SAE plug when you're not riding."

    My experience: Two RTs, a 2008 and a 2015...total riding 10 years, about 100K miles both with batteries maintained by Optimate-4s. No problems with batteries or bike electronics.

    Thanks for the info. So your manual essentially says same as mine - - do not hook charger directly to battery unless battery is "disconnected" from bike.

    I wouldn't be surprised if pretty much all relatively recent BMW owners manuals have same language.

    I am just going to keep using the sae plug and the trickle charger.

    Thanks everybody.

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