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Battery woes

Discussion in 'Technical and Troubleshooting Torque' started by DragonCypher, Nov 13, 2009.

  1. Bike - 1984 Honda Integra VT250F
    Battery - CB9-B, <6 months old

    In the past I've only had 2 problems with the battery..
    where the bike overheated in Brisbane traffic, stalled and then everything boiled and drained the battery. It wouldn't charge up again until I plugged into a charger overnight, then was fine.

    More recently, I somehow managed to leave the lights on.. how? I don't know because they're wired up to the ignition.
    But it happened, and was fine again after riding for 5 mins.

    Now yesterday I went to north Brisbane and back, ~480kms. Half way there I stopped for fuel. Then got to my destination where I was picking something up.. And then left again, no issues there.
    Halfway back home I stopped for fuel again and upon trying to leave the battery was flat.
    Jump started it with help from a random dude in a 70's style porsche (had bad experience with cam timing and push starting in the past....)
    And headed home.
    After the trip home its still flat

    I grabbed a multimetre out today and found its about 12.2V, when cranking it drops to around 4 ish and will only turn over about 3 times
    But once going it sits at ~12.5V idling, up to 13.8V at 6,000rpm

    Is that fine, or not high enough?
    The service manual I have can only suggest the battery acid is low (checked that) or specific gravity is low.. and I dont have a hydrometre to check that
    Also said to check the charging circuit with amps rather than volts, but only if the battery is in good condition first or it will give false readings, and I can't be certain it is.

    If i took out my battery and plugged in a random 12V car battery to test the charging circuit would that still work?

  2. Sounds like the battery is rooted. You should get some voltage drop when cranking, but 4V is way too low. The history of two total discharges will not have done it any good. Some batteries will survive that but it will shorten their lives and it looks like you've been unlucky and one of the battery's cells has cried "enough".

    Yes, you can hook up a (not flat) car battery to your bike without killing anything and this will allow you to check the charging circuit properly.

    Incidentally, you probably can't leave the headlamp on without the ignition on, but most bikes have a parking lamp position on the ign switch which will leave the tail light and the front pilot lamp on when you take the key out. It's not difficult to do this accidentally and it will flatten your battery as surely as leaving the headlamp on would. Just a bit more slowly.
  3. Hmmm, tried an edit but the site wouldn't let me for some reason.

    Anyway, just to add that the running voltage readings you give sound fairly healthy. Healthy enough for a 25 yo charging system anyway. Generally if there's a problem, you won't see the change in voltage between idling and higher revs. It's called a rising volt test and is also a worthwhile check on any electrically suspect secondhand bike you're contemplating buying.
  4. 13V+ sounds like your charging circuit is fine so it's to do with the battery. Overheating? Maybe you boiled away the electrolyte? Is the electrolyte low? Demin water top up if yes...

    Batteries do lose "charge" over time. As they discharge, products build up on the internal plates. If those products fall off, then they can't be converted back during the recharge cycle. Another thing is are the terminal clean? Oxides can build up on the terminals causing large voltage drop...
  5. Terminals are clean, sanded all connections and sprayed with electrical protectant stuff when I first installed it.

    I'm not even sure what an electrolyte is, let alone how to measure them.
    But when I got it, and filled the acid, it was just that.. all acid and no distilled water.
    The levels are still halfway between min and max, 0.5cm below where I filled it to 5-6 months ago
    I've currently got it hooked up to a charger where I'll leave it overnight to see if it holds anything

    But my main concern is why would it go from perfectly fine, to completely dead WHILST riding?
    When I left brisbane I started it (even with headlights already on) and it started instantly, no hesitation or anything. Once I reached the Ipswich servo though.. it wouldn't even turn over more than once
    And after the trip home from there with a charging system that works, its still dead.

    Conveniently enough a storm has just turned up so I'll wait until tomorrow when the charging is done to see how it turns out
  6. it happens, the battery is probably under manufacturers warranty, so take your invoice and get it replaced.

    Failing that it's time for a new one.
  7. Maybe also check the starter motor has not decided to die.
    Recently had a problem with the R1 where the bike would not start after riding, even for 5 mins, but using jumper leads to a car would let it start.
    It was found that it was dumping the power, voltmeter showing that volts dropped a fair bit, giving indication that battery was flat, or charging circuit was not doing its job.
    Replaced starter, works like new....
    • Like Like x 1
  8. Sounds like the battery has dropped a cell (or a few). I had a dirtbike which did that to me. Idling/charged voltage was at a happy 12.5-14v. The moment I started cranking -> 3-4v.
  9. After charging overnight it works like new again..

    Which i was afraid of, because that still doesnt explain what happened

    The only thing I did differently during the runs that the battery went flat.. was using high beam, so I'll look into that and see if using high beam draws excessive amounts of power when it shouldn't

    Also the starter motor appears to work perfectly when the battery is fully charged

    I have also found the receipt for the battery just incase it happens again..
  10. Yep, my starter motor worked fine when battery was fully charged.

    Start the bike, take it for a 5 minute run, stop it, then see if it starts....

    When the bike was hot, it would seem that the battery was flat, but is was fine....
    • Like Like x 1
  11. Interesting... :-k

    But wouldn't that mean after cooling down for half an hour it can start again?

    [edit]: Also today I went to supercheap and back, then KFC and back (oh yeah I'm a health nut etc)
    So started it 4 times without issue