Bad Battery???

[89 fxrs]

a friend just bought a used 2012 road glide so not sure how old the battery is, but  he had it on a tender and the green light was on but it won't start the bike - it turns over really slow so I put a volt meter on it and it shows 12.85, which I believe is a full charge - any explanation on this? tender shows it charged , the volt meter shows it fully charged but it doesn't have the juice to start the bike, can a battery show all this and not have the cranking amps to start it up?

[Hossamania]

Yes, it's possible. First, double check all the battery connections, I would even undo them, clean them, and reconnect. If that doesn't work, put a jump on it. Last, try a new, known good battery.

[Coyote]

You need to measure the voltage under load.

[Hossamania]

Yes, it's possible. First, double check all the battery connections, I would even undo them, clean them, and reconnect. If that doesn't work, put a jump on it. Last, try a new, known good battery.

I meant to say, if it starts with a jump, your battery is probably bad.

[FSG]

he had it on a tender and the green light was on but it won't start the bike - it turns over really slow so I put a volt meter on it and it shows 12.85, which I believe is a full charge -

it should be better than that having been on a/the tender, so IMO it's toast

but as Coyote says "You need to measure the voltage under load", which is the first thing to do when a meter is available.

[89 fxrs]

How much of a voltage drop would qualify it as toast?

[guido4198]

Voltmeter readings are no guarantee that a battery has the power to start the bike.
LOAD TESTING...by someone who knows how is the only way to KNOW (by test).
Of course...if a known good battery or jump will start the bike, you'll have your answer.

[Hossamania]

How much of a voltage drop would qualify it as toast?

Reading some past posts, it seems that it should not drop below 10 volts while cranking, but I'm not sure how accurate that is. Of course, a proper load test is best.

[smoserx1]

Voltmeter readings are no guarantee that a battery has the power to start the bike.
LOAD TESTING...by someone who knows how is the only way to KNOW (by test).
Of course...if a known good battery or jump will start the bike, you'll have your answer.

  Amen to that advice.  The last battery I had go bad failed so badly the only sign of life was one of the LED passing lamps would slightly flicker...about as bright as a candle.  Obviously the starter would do nothing, not a sound.  The battery showed 12 something volts no load but as soon as the ignition switch was turned on the voltage dropped to less than one volt.  I have had 2 go out like this.  When they are this bad you can't even jump them.  The shorted battery will consume nearly all of the host battery's power.  If you are VERY careful you might be able to test it as follows: 

Disconnect the negative battery cable, make sure it is not touching the battery.  Hook the host battery with jumper cables, positive to positive, but negative to the motorcycle frame, preferably on a non-chromed bolt like the starter mounting bolt.  Then turn on the switch and try to start the bike.  Doing it this way isolates the suspect battery so it cannot suck power from the host, but you do risk creating an arc where the negative cable grounds to the bike, so make sure the connection is secure and the ignition switch is off before proceeding.  This procedure was safe on cars years ago, if it is dangerous to new vehicles with electronics someone chime in cause I don't want to give bad advice.

[Scooterfish]

  with Hoss, if it drops below 10 volts cranking replace the battery.

[Billy]

a friend just bought a used 2012 road glide so not sure how old the battery is, but  he had it on a tender and the green light was on but it won't start the bike - it turns over really slow so I put a volt meter on it and it shows 12.85, which I believe is a full charge - any explanation on this? tender shows it charged , the volt meter shows it fully charged but it doesn't have the juice to start the bike, can a battery show all this and not have the cranking amps to start it up?

Easy and accurate load test; disconnect fuel line from bottom of tank, connect volt meter to battery, engage starter for 10 seconds, if voltmeter at any time drops below 10vdc replace battery.

[motorhogman]

There should be a date code or actual date on the battery. ?  If it's original it's toast.

[chaos901]

I found a battery tester that seems to work well, you hook it up, enter the specified amount of CCAs, whether the battery is in the vehicle or not and hit TEST.  Found it to be reliable and tested some new batteries too just for giggles, they always came back good. 

The brand was ANCEL.

[Deye76]

If you don't have the testing equipment, pull the battery take it to a auto parts, they will load test.

[Panzer]

You need to measure the voltage under load.

Right on........try starting with meter connected, then read voltage.

[a_disalvo]

First thing I would do is check ALL connections, especially the grounds and connections to the lead post of the battery. Than put the voltmeter on the battery when you are cranking the motor. Should stay above 10 VDC. Frank

[Hossamania]

Has the issue been determined and solved yet?