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Graigcat

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dead battery
« on: May 07, 2009, 11:59:38 AM »
i have a 79 cb 650... i just got the bike dialed in the battery was fine yesterday and today i rode it got home turned it off and then it wouldnt start i charged the battery and it started but i turned it off and the same thing happend so i charged again tested it it said 11.9 volts, i took it for a cruise and tested it when i got back and it said 10.5.. something is sucking juice any ideas what it could be?
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Offline Gordon

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Re: dead battery
« Reply #1 on: May 07, 2009, 12:07:57 PM »
Fully charged should be 12.6 volts.  Check the voltage while it's running.  If it doesn't start going up once the engine hits around 2500-3000 rpm then somethings wrong with the charging system. 
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Offline TwoTired

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Re: dead battery
« Reply #2 on: May 07, 2009, 12:34:16 PM »
A fully charged and rested battery should be 12.6 V.  If it was just removed from the charger, it should be 13.8V or more, (allowing for it's surcharge).

11.9V is a dead battery, or one that is depleted.  You have to be sure the battery is good and fully charged before checking the charging system.

650's seem to frequently have rotor issues in the alternator, though.  If I suspected the charging system, I'd start by measuring it's resistance.
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Offline myhondas

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Re: dead battery
« Reply #3 on: May 07, 2009, 01:01:14 PM »
Go get a hydrometer and check each cell for it's specific gravity. All cells should be pretty much equal. If not, you have a bad/shorted cell which is dragging the others down. If all check out OK... then it is your charging system.  See above on TT's reply.
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Offline OldSchool_IsCool

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Re: dead battery
« Reply #4 on: May 07, 2009, 01:16:17 PM »
Or take the battery to your friendly neighborhood auto part dealer and they can test it in a matter of a few minutes.  If the battery is toast, they will prolly have the replacement right there.
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Offline TwoTired

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Re: dead battery
« Reply #5 on: May 07, 2009, 01:27:36 PM »
Quote from: OldSchool_IsCool on May 07, 2009, 01:16:17 PM
Or take the battery to your friendly neighborhood auto part dealer and they can test it in a matter of a few minutes.  If the battery is toast, they will prolly have the replacement right there.

I'd like to know how they can test it without giving it a charge cycle first.  They can tell you if it isn't charged (and sell you a replacement).  But, they can't tell you if it won't take and hold a charge without first trying to charge it.  And, while you can take a 120 amp rate out of a motorcycle battery, you aren't supposed to charge it over 1-2 amps max.  This takes more than a few minutes.  Of course, if it HAS a dead cell, that will fail it right away.

Cheers,
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Lloyd... (SOHC4 #11 Original Mail List)
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Offline OldSchool_IsCool

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Re: dead battery
« Reply #6 on: May 07, 2009, 02:30:03 PM »
Quote from: TwoTired on May 07, 2009, 01:27:36 PM
Quote from: OldSchool_IsCool on May 07, 2009, 01:16:17 PM
Or take the battery to your friendly neighborhood auto part dealer and they can test it in a matter of a few minutes.  If the battery is toast, they will prolly have the replacement right there.

I'd like to know how they can test it without giving it a charge cycle first.  They can tell you if it isn't charged (and sell you a replacement).  But, they can't tell you if it won't take and hold a charge without first trying to charge it.  And, while you can take a 120 amp rate out of a motorcycle battery, you aren't supposed to charge it over 1-2 amps max.  This takes more than a few minutes.  Of course, if it HAS a dead cell, that will fail it right away.

Cheers,

Good points all.  The last time I took a motorcycle battery in, the 5-minute test was inconclusive.  I left it with them for a few hours for another test which came back bad.  It didn't surprise me as I strongly suspected the battery's ability to pack enough coulombs for more then 15-20 seconds of cranking.
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Can I have a motorcycle when I get old enough?
If you take care of it.
What do you have to do?
Lot’s of things. You’ve been watching me.
Will you show me all of them?
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Offline Gordon

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Re: dead battery
« Reply #7 on: May 07, 2009, 02:46:27 PM »
Quote from: TwoTired on May 07, 2009, 12:34:16 PM
11.9V is a dead battery, or one that is depleted.  You have to be sure the battery is good and fully charged before checking the charging system.


It's been my experience that even with a depleted battery, as long as the engine is running you will still see an increase in voltage at the battery terminals if the charging system is working.
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Graigcat

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Re: dead battery
« Reply #8 on: May 10, 2009, 10:21:25 AM »
ok so a little update i charged the battery... it was at 13 whatever i rode to work fine... when i got off work i wouldnt start push started it let it warm up... my headlight and taillight started flashing and when out but my gauges were shining bright.. i turned it off and now it starts up fine everytime.. but no headlight taillight or brakelight... short in the wires or is it grounded??
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Offline myhondas

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Re: dead battery
« Reply #9 on: May 10, 2009, 03:56:06 PM »
Sounds like you need to pull your headlight and check you wiring harness in the shell. Sounds like it could be either.


ray
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1974 CB 750 K4 SHOWROOM
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Offline Gordon

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Re: dead battery
« Reply #10 on: May 10, 2009, 04:21:44 PM »
Could also be the ignition switch. 
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Offline Frankencake

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Re: dead battery
« Reply #11 on: May 10, 2009, 05:34:06 PM »
Sounds like a cb650 to me.  :P  Flame me if you want, but I have had nothing but trouble with these bikes.  Great motor<bunk electrical.   :'(
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Graigcat

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Re: dead battery
« Reply #12 on: May 10, 2009, 09:28:42 PM »
Quote from: 78SS on May 10, 2009, 05:34:06 PM
Sounds like a cb650 to me.  :P  Flame me if you want, but I have had nothing but trouble with these bikes.  Great motor<bunk electrical.   :'(

i agree entirely.. haha its been nothing but trouble but i love it to much.
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Offline Hush

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Re: dead battery
« Reply #13 on: May 10, 2009, 09:52:33 PM »
Good on you Craigcat, you are in the majority of 650 owners who love to hate their bikes.
My 79 CB650Z has had nothing but trouble with it's charging system, I replaced everything from regulator and rectifier to stator and finally I chucked in a borrowed rotor and it all goes perfectly now.
My rotor tested OK too but it must have been screwed inside, other 650 owners tell me same story and a replacement rotor seems to fix some...but not all!
Check out forum member "Kit's" HOT START/CHARGING ISSUES thread also mine EX POLICE CB650PZ it makes for some interesting reading once you hit the electrical side of things.
Why Honda could make such a good looking bike yet load it with such a weak charging ciruit amazes me, I mean to say they are only 30 years old! ;D

         WELCOME TO HONDA CB650 HELL HE HE HE HE HE...............
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I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

Graigcat

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Re: dead battery
« Reply #14 on: May 11, 2009, 10:28:31 AM »
well i just bought a new wiring harness sooooo hopefully that should fix the problem...
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Offline Hush

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Re: dead battery
« Reply #15 on: May 11, 2009, 09:22:10 PM »
New harness....NICE....just don't toast it, that problem may still be there in a component waiting to cook the new harness too.
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I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!
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