Anyone using a Odyssey PC925L Battery?

Discussion in 'Airheads' started by bmwhacker, Feb 8, 2013.

  1. bmwhacker

    bmwhacker Still on 3 wheels

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    I've been using an Odyssey PC 680 Battery for 4 years and it's apparantly getting "tired". Would like to go with a larger battery. The PC680 is the smaller battery. I'm cranking a R100S motor and running a couple accessories.
    My bike has the large battery box (1974 R90/6 Frame) so the larger PC925L Battery should fit. The "L" designation apparently is for a reversed pole arrangement. I take that this means that the battery can be laid over to fit in the BMW battery mounting frame, with the terminals towards the front. The PC925 is heavy...25 lbs. Looks to me like it will be a very tight fit getting it in there. Anyone around here installed this battery with the "reversed" arrangement?
    Can a guy "shoe horn" it in there without disassembling the bike?
    #1
  2. batoutoflahonda

    batoutoflahonda Long timer

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    How did it crank when the battery was new? If it was fine I wouldn't bother with a bigger bat. Other things to look at are worn starter. Throwing more cranking power at it might be masking another issue.
    #2
  3. camgregus

    camgregus riding gently now

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  4. bmwhacker

    bmwhacker Still on 3 wheels

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    I thought maybe I had a starter issue to begin with. I removed the starter and took it down to the bare bones. Lubed all bushings, cleaned and carefully dressed up the commutator surfaces. The brushes looked good.
    I cleaned all connections involved with the starting circuit. I'm fairly certain that the starter / charging circuits are OK.
    The battery just doesn't seem to want to hold a 100% charge.
    #4
  5. _cy_

    _cy_ Long timer

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    to test battery ...

    1. charge at least overnight with preferably a std size automotive battery charger. some batt tenders charge so slow, it may take several days.

    2. allow fully charged battery to rest overnight to bleed off surface charge

    3. use a known to be correct meter ... 12.85v shows a fully charged flooded PB at rest, 13v for AGM

    4. next is a load test.. no problems if you don't have a load tester... your starter will draw about 150amp, then drop to about 95 amps. if your battery cranks strong with a verified full charge, then it passes the load test.

    5. your charging system should put out at mid-rpm range.. 13.8v to 14.2v measured at battery. intermittent charging issues are the worst...

    6. test for parasitic drain... set meter to measure amp in series ... connect meter in series to neg side between battery and ground. depending on what's running with everything shut down, a tiny drain may be ok... like a clock
    #5
  6. supershaft

    supershaft because I can

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    There are guru websites that say your airhead should be charging at least 14 volts. I have tested a lot of airhead charging systems and I have never seen a stock setup charge over 13.9 volts at the battery. They will charge over 14 with the police regulator but . . . . Over 14 will cook wet cells dry. F650's charge around 14.2 volts like some say airheads should charge and they very often have a bone dry battery in 6000 miles. 13.7 to 13.9 is real good for our airheads.

    Static battery voltage is almost useless info. How much does it drop with a load on it? Dropping below around 10 volts is suspect and below 9 or 8 is no good. If you are using a load tester, it all depends on the tester and how much it loads the battery. Use the smaller 'motorcycle' testers. Don't test them too much! It's a super drain on even a good battery.

    Surface charge? You don't want to over heat a battery charging it or draining it. Other than that you don't need to wait. I let wet cells self charge for an hour or two after filling them. They will over heat if you charge them right after putting the acid in.
    #6
  7. H96669

    H96669 A proud pragmatist.

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    Before you discount the Odissey, do you have a proper three stages charger for it? I had to leave mine on float for quite a few days to get it back to 13.1x Volts and Odissey does have specs for the minimal float Voltage. Some of that is in the Owner's manual but more in the technical manual online on their site.

    Mine is on a K-bike with better charging, 14.3 not a problem but still was only getting 12.8-12.9 out of it after long rides and time to remove the surface charges. Long float brought it back up and still there 2-3 weeks later, just checked it today.

    But our "sort of local" Odissey dealer would also do a health check and proper charging. I may have paid a little more than online but should include some service. Was worth it anyway if just to talk to the knowledgeable sales guy and get some info I wanted.:wink:
    #7
  8. Rucksta

    Rucksta SS Blowhard

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    I had a 680 that did 4 years service then sat on the bench 4 years waitinng for the 320 replacement to get tired.
    Hard starting due to lack of choke and no accelerator pumps then running at low speed with the lights on is what killed the 320.
    The 680 stepped up and has done another years work with no sign of reduced capacity from the 4 year hiatus.

    The Odyssey AGM is not a deep cycle house battery; it is optimsed as a starting battey and needs to be kept at a float level higher than a lead acid battery.
    A normal charger will do to get by for a flat battery event.
    For continued maintance a 3 stage floar charger is required or better again ride the bike at least once a month.



    Maybe you have a charging or a starting problem rather than a battery problem.
    #8
  9. ignatz72

    ignatz72 call me iggy

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    I've used a PC-925L in both an 83 RT and a 93 GS, and it's a fine battery.

    If you rule out a parasitic drain or bad charging issue as mentioned above and still want a larger capacity battery, the 925L is great (if you're not weight conscious).

    In both bikes I've used one, I did have the motoelekt.com VR, which helps keep it charged.
    #9
  10. Les_Garten

    Les_Garten Been here awhile

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    I've got a PC-925L in my '92 RT. Fits fine. Gotta fiddle a little with the connectors.

    When it's not in the RT, It sometimes moonlights in a Porsche 930.
    #10
  11. chollo9

    chollo9 Screwed the Pooch

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    If you don't do this, you cut battery life by a huge amount--it doesn't matter how much care you take from this point forward.
    #11
  12. apt13

    apt13 Been here awhile

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    been using this battery in my 78 r80/7 for multiple years. no problems whatsoever. but it is a pain to remove/install. it's too big to just pop in through the top. I have to take apart the airbox and jimmy it in through that area.
    #12
  13. bmwhacker

    bmwhacker Still on 3 wheels

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    I thought that might be the case.
    Looking at the given dimensions I thought it might be a pain to get it in there,
    #13
  14. Les_Garten

    Les_Garten Been here awhile

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    Mine dropped in from the top on my '92 RT, snug but it goes in.
    #14
  15. AntonLargiader

    AntonLargiader Long timer

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    Too heavy. If your bike won''t start with a PC680, it might not start with the 925 either. Better strap a second one on the rear rack. Maybe a third one somewhere else, if you can find space.
    #15
  16. bmwhacker

    bmwhacker Still on 3 wheels

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    Smart ass.....:lol3
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  17. AntonLargiader

    AntonLargiader Long timer

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    I think I know where your thinking is taking you, but 50% is an arbitrary number. Here's how I look at it: the 680 is more than good enough under normal conditions. Under abnormal conditions, the 925 might not be good enough either. So there's a narrow range (abnormal conditions where the 680 fails but somehow the 925 hasn't also failed) where it's worth carrying around all that extra weight. Maybe 50% is in that range, I dunno. How about 60? 95? 10? 1? What failure mode are you planning for?

    I said, "Too heavy. If your bike won''t start with a PC680, it might not start with the 925 either. Better strap a second one on the rear rack. Maybe a third one somewhere else, if you can find space." I don't read your statement in there anywhere, but maybe you read differently than I.
    #17
  18. bmwhacker

    bmwhacker Still on 3 wheels

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    The PC680 I have has been in use for 4 years (or so). It doesn't want to hold a full charge for more than a couple days any more.
    I'm not particularly planning for any "failure mode", just tired of fighting a dead battery and simply wondering if it makes any sense to install the larger battery that the bike is supposed to have. But.. "yikes"...:eek1...the 925 weighs 25 lbs as you said..
    #18
  19. AntonLargiader

    AntonLargiader Long timer

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    Sounds like you just need a new one. Four years, that's a bit short. Overcharged or allowed to go flat ever?
    #19
  20. 100RT

    100RT Long timer

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    I was given a used 680 about 5 years ago. I installed it in my 81 R100RT until last fall when I got a brand new free one.

    I returned it to the original owner so he could put it in his riding mower. My guess is that it has been in use for 8 trouble free years so far. Also have a new one in my 03 R1150RT, which has more compression and cc's to contend with.
    #20