I was checking the battery levels....

[coffee_brake]

Because it's been hot I thought it would be a good idea to check the levels in my standard-type battery. I know, I know, but the last battery left me stranded so I had to get what was available and that was this standard type battery.

With my little clutch problem this week, the bike was VERY hard to start and finally just wouldn't at one point till I let it sit. Once the bike sits it seems to start right up. It's when I shut it down at the lights that it has a hard time starting.

The battery wasn't low on fluid at all. It never has been. It is less than a year old. After just sitting in the bike all night (about 85 degrees outside), the voltage is 12.26, which is not good. I don't want to take it to Deal's Gap like this.
Before I buy a battery, are there known issues that would keep a perfectly good battery from receiving full charge from the RR?

I see something about a crimp, gonna check it out and do that today.

If I check the voltage with the bike idling, what should that be?

Should I also check the voltage while revving the bike? what should those numbers be?

I'm a newb with the multimeter, I'd appreciate it if somebody knows what numbers I should look for...

 

[one2dmax]

A full charged battery is 12.6 volts (2.1v per cell). A full discharged battery is 12.43 (though they will sometimes start the vehicle with less then that). Charging voltages desired are typically 13v-15v. Much higher then 15 and the battery overcharges boiling out the fluid and warping the plates inside. Lower then 13 and your energy consumption may use up battery charge faster then it's put back. Idle voltage is typically lower then voltage when revved. Also, there will be a voltage "spike" on first startup due to battery needs as the system tries to charge the battery quickly.

The stator puts out raw 110 A/C current and the regulator converts that to the D/C output.

The battery is only there to provide starting power. After the initial start the battery is not even used and the regulated power supplies all the bikes needs (you could even drive all over without a battery installed even once it's started).

The crimp fix simply reduces lost current through the poor connection type from the factory. A newer model regulator (99 and up) will put out a more stable current then the older units (and some use the digital regulators like modern sportbikes have).

A larger output stator like Ventures use (and some aftermarket units) will have more available current. We don't normally need them if the system is working correctly. The venture flywheel is heavier and more magnetism which will also help generate more electrical current. It will make the bike run smoother but make the engine rev slower.

 

[coffee_brake]

Good information, thanks.

The battery charged to 13.6 volts on the charger. Ten minutes later just sitting there, it is now 12.75 volts.

Is that enough to go on with, or is the battery on its way out?

 

[MaxMidnight]

Measuring the voltage just afer you have taken it off the charger (or run the bike) will give an inaccurate reading due to 'surface charge' on the posative plate of the battery.

To get the correct voltage you would need to let the battery stand over night or leave the lights on for a couple of minutes.

This will dissapate the surface charge and you will be reading the correct batery voltage.

 

[one2dmax]

Correct, a few cranks will pull off the surface charge. Watch the meter when cranking too. If the voltage drops below say 10v then the battery may be sulfated (corroded internally) enough to warrant replacement.

Sean

 

[coffee_brake]

OK. I haven't put the battery back into the bike, it's been sitting for a couple hours and voltage has dropped to 12.64. I can give it a while longer to see how much it drops. If the battery is going bad I need to find a replacement quick. Heading out for Deal's Gap on Friday.

Thanks a bunch for the info...I'm just trying to figure out if it's the battery not holding a charge, or the bike not providing one.

 

[one2dmax]

12.6 is fully charged so it's ok so far. But, keep in mind there is a difference between holding a charge and it being able to provide a current enough to do the job. The battery may very well be ok but that's what the cranking voltage test shows you.

Batteries "rust" (Sulphate) inside and the more it's sulphated up the less good storage area there is for the power.

 

[coffee_brake]

I put the battery in the bike, it was showing 12.5 volts.


When I hit the start button, it only dropped to 11.5 volts and then very slowly began to come back up. After a full minute it showed 13.5 volts.

BUT when I rev the bike the voltage does NOT increase.

What does this mean? Is something wrong? Shouldn't the voltage come up when I rev the motor?

 

[coffee_brake]

Also...the book says there should be .3-.45 ohms of resistance between the terminals of the stator coil. I'm getting .6 on both. Is my battery having a hard time getting voltage? And why is it so hard for the starter to turn the motor when it's hot?