R80 elec. drain.

Discussion in 'Airheads' started by ritetwist, Jul 23, 2013.

  1. ritetwist

    ritetwist Been here awhile

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    1985 bike, had it for a couple of years, always been reliable.
    Went to start it 2 weeks ago and the battery was flat, no life at all.
    I hooked up a trickle charger for a bit and boosted it,rode for 20 min.With engine off, key on, it showed
    some life at the indicators.
    I left it parked till today,flat again, not even a glimmer;
    What is the best procedure for finding a leak?
    I am assuming the battery is still good.
    Thanks in advance.
    #1
  2. bpeckm

    bpeckm Grin!

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    Don't ever assume anything about the battery.... we used to say "it's always the battery...."

    :evil
    #2
  3. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    What are some voltages? Assuming without measuring is spelt ass-u-me.

    --Bill
    #3
  4. disston

    disston ShadeTreeExpert

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    It sounds like you need a new battery. An old battery will not hold a charge. If you measure the voltage on the sitting battery after it has been charged it should have a minimum Voltage of 12.5 to start the bike.
    #4
  5. Warin

    Warin Retired

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    Charge the battery back up.

    Measure the CURRENT from the battery to the bike.... that will tell you if there is a constant drain to the bike.

    If there is significant drain (say >10mA) then, while measuring the current, remove fuses one at a time and see which one takes the drain current. If no fuse effects the drain current then it is either an unfused load (starter motor/alternator) or you have forgot something.


    ASSUMPTIONS:
    The bike charged the battery while you were riding ... you did have TWO red lights when you turned the ignition key on ???? If there was only one then may be the alternator rotor is open circuit....
    #5
  6. Cogswell

    Cogswell Spudly Adventurer

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    For good reason !

    First things first, all testing should be done with a fully charged battery. Charge the battery fully, after charging take it to your local battery shop or auto parts shop and have them "load test" the battery to verify it's condition.

    If the battery is good continue with checking your charging system function and then checking the system for a draw.
    P.S. There is not much on these old bike to cause a current draw that is not very conspicuous.:deal

    Let us know what you find.

    :freaky

    Mike
    #6
  7. ritetwist

    ritetwist Been here awhile

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    I just took the charger off.Trickle charged for the last 12 hrs.(2 amps)
    Battery reads 12.5 volts.Lights are bright with the key on.I did not start it.
    I am going to let it sit over night and check it A.M.
    Not to sound like an electrical newbie (there's no hiding it now).Where would I put the test leads to find the current draw to the bike?
    I may get a chance to remove the battery and load test it tommorrow,but I may as well learn something now.
    Tks.
    #7
  8. Cogswell

    Cogswell Spudly Adventurer

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    Disconnect + cable, connect meter between battery + terminal, and + cable. Set DVOM function to amps. Display should show any draw on the battery.


    Mike
    #8
  9. bpeckm

    bpeckm Grin!

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    That ^ takes a special meter... not many people have meters capable of measuring more than milli-amps. Starter shop would have ways of checking draw during starting, as well as charging.

    Easy to check the battery, though, and by far the most likely culprit!

    Another "quick and dirty" way to test for some sort of static electrical draw is to disconnect the battery (neutral is always safest to disconnect) and touch the neutral cable to the neutral battery terminal....if there is any spark or sizzle, then there is a load somewhere. Then you can pull fuses, as mentioned above, one by one.

    But I still suspect the battery.....

    :evil
    #9
  10. Warin

    Warin Retired

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    But he is not checking starter current!!!!!!!!!

    ..but drain current while the bike is SWITCH OFF.. should be less than 10 milliamps ... No special meter ...

    The safe way to measure battery drain current ...

    1) Put meter into current mode - usually means using another terminal on the meter. Set it to a large current, you can change the scale later if the reading is 0. Remember the manual you probably cannot find now? Yep .. RTFM.

    2) Connect meter between the battery NEGATIVE terminal and the batteries NEGATIVE leads. Now disconnect the battery negative lead/s from the battery. This leaves the battery negative terminal connected through the meter. Don't use the positive side as any mistake there could cause damage, the negative side is much safer.


    WHEN YOU FINISH .. don't forget to disconnect the meter leads and set the meter back voltage (or off). Failing to do so will mean when you next go to measure voltage you will blow the meter (hopefully a fuse inside the meter).
    ============================
    DC not AC. No 'neutral'. Earth, ground, + and - yes ... no neutral.
    #10
  11. chollo9

    chollo9 Screwed the Pooch

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    Disconnect negative cable. Connect test light between cable and terminal. If lamp lights, you have a drain. To find where the drain is, systematically disconnect circuits or components until light goes out. When it does, you have located your problem.
    #11
  12. ritetwist

    ritetwist Been here awhile

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    Thanks,you are definitly talking to my level.
    I just checked the battery, reading 12.5 VDC, same as 10 hrs. ago.
    I will do the - (ground) disconnect today and see if I get a reading from - post to grounding point.
    I will keep in touch.
    Thanks for the help.
    #12
  13. bpeckm

    bpeckm Grin!

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    Correctomundo.... my errrrrorr...... :evil
    #13
  14. Warin

    Warin Retired

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    Too easy to fall into yer normal trade descriptions, and easy enough for the educated to understand what you mean. But it confuses newbies and is not good educational practice. :1drink

    ------------------ chollo9
    Using a lamp to indicate the presence of current will work only if the current is large enough to make the lamp glow, thus the lamps power rating will determine the sensitivity of the indication. As a meter is present it can be used without going into calculations of lamp sensitivity vs power rating ... KISS.
    #14
  15. ritetwist

    ritetwist Been here awhile

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    Ok, gents.
    I started the bike about 6 hrs. ago.Took a bit of turning (30 sec. max.,not steady, 6/10 sec. bursts)until I switched to reserve.
    Started and ran good Alt. light went off ~ 1500 rpm.I just ran it a bit for a friend who is trying to get me to sell it to him.Battery was running down a bit at the end of the starting attempt.I put the charger on again, still on.Reading 12.5 / 13 Volts.
    Then I got a brain wave.Disconnected the charger from the battery and took a reading on the charger only. 4.5 Volts !
    It doesn't make sense that 4 3/4 volts could be used to charge a 12 volt battery ??!!
    I took another charger and checked it, 12.5 volts output.
    Does that mean the charger I have been using for a couple of years is NFG ?
    The one I have on now is an older one,2 amp output, not auto shut off.
    New one is 1.5 amp.
    Could any of the 3 or 4 batteries I have replaced in the past been ok with a proper charger?
    The newer one I checked @ 12.5 volts has an auto shut off and I will put it on for tonight.
    I will check that aspect from now on.
    I did not get a chance to disconnect to check for drain yet.
    Tks.
    #15
  16. bpeckm

    bpeckm Grin!

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    Where's the icon that shows a forehead-slap saying.... duh!!

    Of course, 4.5 volts will not charge a 12v... it takes a higher-than-nominal voltage to charge anything! You may be on to something!

    Will look for the manyana post.....:eek1




    :D
    #16
  17. ritetwist

    ritetwist Been here awhile

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    Update,the newer auto charger was set to 6 volts, gave a 12.5 volt out put reading.
    Set on 12 volts, shows about 22 volts output.
    The battery is already showing 13.5 vots and still charging.
    Old charger is in the dumpster.
    My forehead is sore.

    Where are those old batteries?
    I don't often throw things away.
    #17
  18. Warin

    Warin Retired

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    Take old charger out of dumpster. Solves 4 and 1.
    Drink beer. Solves 2.

    The old charger may just have a faulty diode or two. Can you open it and look inside? If you cannot do it .. take it to your next swap meet or bmw club meeting .. give it away. This helps with 3 as you now have given penance for that.
    #18
  19. ritetwist

    ritetwist Been here awhile

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    Thanks W.
    Before I threw the old charger out, I cut the AC cord off. Future use as a pig-tail for checking motors / pumps / lights,etc.I also cut the DC cord with the alligator clips on it, helps for testing DC hookups.
    I found 4 batteries that I can charge and load test, there may be some salvation there.
    Thanks for the help.
    A lesson well learned. Painful to admit.
    #19
  20. bpeckm

    bpeckm Grin!

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    All is well in the world.





    Have another beer.




    :evil
    #20