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how do i tell if a motorcycle battery is dead?

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by daedalus, Nov 6, 2011.

  1. it goes completely flat after 1-2mth of not using

    i can charge it up again (~12hours) and then it works

    but after 1-2mth it goes flat again.

    does that mean its dead and i should replace it?

    its a no brand about 2.5years old

  2. My bike does the same thing. I found that if I use the kill switch as well as turning off the ignition then the battery stays charged. So for me, I think I have a small battery drain.
    Electricity is like black magic to me, so I have no idea how to narrow down where it may be.

    You may have a similar problem.
  3. normal for a bike battery if you don't ride the bike for that long
    some people hook up trickle chargers if their bike is going to be of the road for that long.
  4. +1 to Spenze you more than likely have a small drain current of some description. If you know you are not going to use it for a couple of months disconnect the battery and then reconnect and try next time you are going to use it. This will show if it is a battery with an internal fault or a bike drain. A certain amount of self discharge is inevitable though.

    If the bike has infrequent use then it may be worth getting a maintenance trickle charger.
  5. And letting it go completely flat is likely to stuff it. Each time it goes flat it dies a little and sooner or later that is goingto be it.

    Easiest thing is to use it more often.
  6. :) :) +1
  7. what voltage is on the battery when it is disconnected from all loads and chargers? You should get about 12.4V minimum, 12.7V normally.

    For a fully comprehensive way to test:

    Battery trouble shooting guide
  8. Holding charge for a month or so isn't too bad. When it can't start the bike after a week of non-use I'd be worrying.

    Mind you, I just pulled the tarp off the Ural last weekend, expecting a good case of flatness and the old Russian Hammer fired on the first compression after more than 4 months of dormancy :D. That's a 3+ year old battery that has received no maintenance during its life.
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  10. How do i tell if a motorcycle battery is dead?

    20min of CPR, if it doesn't start breathing its dead.

    Be careful of acid burns, they're painful on the lips.