Weak battery?

[Hackmachinist]

My cb360 headlight had gotten dim when riding tonight and the starter button has ceased to work this evening. The bike has been sitting for a couple months and is was wondering is this just a sign of a weak battery? Wouldn't running the bike charge it pretty quickly? Would a battery tender solve this? Help!

 

[Hackmachinist]

PS, she has been stalling a bit too.

 

[raptormeat]

what are your running volts at idle and at say 4000rpm?

 

[Hackmachinist]

what are your running volts at idle and at say 4000rpm?

I have no idea! Sorry !!

 

[raptormeat]

charge battery, check back with us

 

[AlphaDogChoppers]

You have to diagnose. You gave us nothing to work with, here. I'm good, but I am not psychic.

If you have a low battery, trying to charge it with the bike's charging system is a bad idea, and can actually cook the charging system.

Consult the service manual. If you don't have one, spend two minutes with your friend Google, and find one that you can download.

There is a procedure for diagnosing charging system problems. First, you have to start with a fully charged battery. You cannot get a legitimate test of the charging system unless your battery is fully charged. Charge it with some sort of battery maintainer like Battery Tender. Once you get the green light, disconnect the charger. Let the battery "settle" for 12 hours. Measure the voltage. It should be 12.6 V or higher. If it isn't, the battery is bad.

Once you have a fully charged, good battery, start the bike. Put a voltmeter on the battery. With the engine reving a little, (like around 2,500 rpm,) You should read at least 13 V. (Even that is on the low side of acceptable.) If you are not getting 13 V or more, your charging system needs repair.

 

[Hoosier Daddy]

Do as Alpha suggests and don't try to shortcut, let the battery set overnight after charging to let it's surface charge bleed off before testing. You may not need a "Battery Tender" brand but use a small amperage charger for slow deep charging. 1 or 2 amp is fine for 8 hours minimum.
An old school tool that is seldom mentioned anymore, largly due to modern batteries being "Maintenance Free", is a Hydrometer, also called an Electrolyte tester. They are cheap and easy to use on a lead-acid battery. It's like a mini turkey baster and you draw a bit of acid from each cell and you read the charge level of each cell. Wether it has balls or a float you an easily tell the state of charge.

You have to know the battery is in good condition and capable of accepting and holding a charge before you can accurately thest the charging system. And for that you NEED and volt meter. You don't need a $300 Fluke with all the bells and whistles, but a $30-$50 DVOM is invaluable for checking electrical systems af all sorts in many ways.

 

[Hackmachinist]

Thanks guys! I put the battery on the 2 amp setting and will leave it on there for aprox 5 hours . I bought a bolt meter this morning and when I reinstall it I will do the test!

Thanks again!