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Thread: Whether or not battery tenders are really necessary

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  1. #1
    Just a happy rider... bobnmona's Avatar
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    Question Whether or not battery tenders are really necessary

    Hi,

    I've ridden lots of different motorcycles over the last 40 years and other than a 1991 Suzuki GSX1100F that really did need to be hooked to battery life-support every minute that I was not riding it, all my BMWs have done very well without tenders at all.

    Granted, I live in northern California, 45 or so miles south of San Francisco, and my weather is great for riding 365 days of the year, I've never suffered from any failure to start for as long as I've had my Beemers, which are ridden at least five days a week.

    The current bike I ride as a daily commuter, three miles to work and three mile back with the occasional ride to Half Moon Bay to eat lunch, is a 2004 R1150GSA that has a nearly three year-old PC680 Odyssey drycell motorcycle battery that is still going strong, despite the fact that it has never been placed on a charger. Since I read another post tonight concerning a battery tender that wasn't able to properly charge the battery, it got me wondering why would anyone else in similar conditions (especially during the summer) need to worry about charging their batteries if they rode daily and made sure that the bike was charging properly?

    I'd appreciate hearing your experiences and opinions!

    Best cheers,

    Rob

  2. #2
    Cannonball Rider #52 darrylri's Avatar
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    Rob, I live just over the hill from you in Santa Cruz. The modern bikes (R1100 and newer) have excellent charging systems. My hexhead bike never needs a charge, either.

    The Airheads that preceded them had excellent charging systems *for their time*, but would not like what you do to your oilhead, because the charging system on those bikes discharges at idle and doesn't really get going until you are well above 2000 rpms.

    My R90S and R65 need to be on a charger sometimes, for this reason.

    My older, 6V BMWs all live on the charger in rotation. The generators on those bikes are only *just* adequate for their headlights, and then only when they are running well above idle. (For example, my 1961 R60/2 has a generator that nominally puts out 45 watts, but has a 35 watt headlight, an 8 watt taillight and a a 20 watt brake light.) Their mechanical voltage regulators do not do a great job of optimizing the charge they put back into a battery, either.
    --Darryl Richman, forum liaison
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  3. #3
    Just a happy rider... bobnmona's Avatar
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    Thumbs up Battery Tender...

    Hi Darryl,

    My introduction to BMW motorcycles was my '94 R100GS, which never had a problem with charging, just like my '04 GSA. However, I can understand that older bikes might not have charging systems that are as capable as these. Although, my '77 Honda CB750K7 is an exception!

    Thanks for the response - happy riding those beautiful Santa Cruz mountains (even in the fog)!

    Rob

  4. #4
    Registered User greenwald's Avatar
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    Smile

    Rob - I live in Wisconsin, where weather temps are changed by Mother Nature a half-dozen times a day, just for good measure!

    The only time a charger and my battery are 'intimate' is over the winter months, where it hibernates down on the basement workbench.

    Otherwise, with a ride each week (not even daily), all seems well. I think the BMW on-board charging system is adequate.

    However, if left alone for too long (say 2+weeks), there may be trouble with today's more complex bikes (nothing more complex than a BMW!) - clocks, internal memories, alarm systems on passive stand-by....all contribute to a drain on a battery (which even if left alone without any 'load,' will still slowly lose power).

    So while all of the bikes of my past (Suzuki's, Honda's, H-D's) did not require diligent charging, newer bikes are different animals from time to time.

    Glad you get out daily on yours - an envious situation.
    Last edited by Greenwald; 08-15-2011 at 01:27 PM.
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  5. #5
    Unfunded content provider tommcgee's Avatar
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    A charger/tender is good to have around if use use battery gear. Bikes? Yeah, I need it in the winter.
    Salty Fog Rally 2007, 2009, 2011, 2012, AND LOOKING FORWARD TO 2014!

    -Tom (KA1TOX)

  6. #6
    Old man in the mountains osbornk's Avatar
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    My bikes live in an insulated garage where the temperature ranges from around 40 in the winter to around 80-85 in the summer. I put a Battery Tender Jr. on them overnight about once a month in the winter. The battery in the 03 is the original battery and the battery in the airhead is a 10-12 year old Westco that I took out of my K75RT. When the battery went bad in the airhead 8 or 9 years ago, I put a new one in the K bike and put the old one in the airhead because the airhead needs less battery than a fuel injected ABS equipped bike. I think where you ride has a lot to do with how long a battery lasts. I live in the sticks and nothing is a short distance from me and a minute sitting at a red light seems like a long time. The battery stays fully charged.
    'You can say what you want about the South, but I almost never hear of anyone wanting to retire to the North.

  7. #7
    Alps Adventurer GlobalRider's Avatar
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    Quote Originally Posted by bobnmona View Post
    I'd appreciate hearing your experiences and opinions!
    One shouldn't need a battery maintainer unless the battery has an issue or there is a more than normal current drain in your electrical system while parked. As for the latter, owners should measure it...its simple enough to do.

    The voltage of R1150 GS Adventure battery will go from 12.9V to 12.8V in a month of non-use. Considering the small drain, that is perfectly normal.

    Batteries will tend to self discharge faster in warmer climates.

    I use CTEK battery charger/maintainers for my motorcycles and car during the off season winter months or during long periods of storage. That is the only time you should need them.

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