NEW BATTERY NOT FULLY CHARGED AFTER RIDE

When not riding my bike’s battery is plugged into a 1.5A maintainer.
And so last fall, right after a ride I connected the maintainer up as always, expecting to see the green “charged” LED lit.
Instead the yellow “charging” LED lit up and about ten minutes or so passed before maintainer indicated that the battery was charged.
I attributed the problem to an aging battery.
It was approaching three years and so I replaced it.

Now, even with the new battery, the problem continues.
This past week I performed some electrical diagnostics.
At 2000 rpm, the output across the battery terminals is 14.5Vdc.
At idle, the output is about 12Vdc.
The resistance on all three alternator stator windings are about .5 ohms.
The resistance of the rotor field coil is about 5 ohms as measured at the slip rings.
The rotor brush lengths are within spec.

I checked the specific gravity of the electrolyte in the new battery and three cells measured 75% (3 balls floating) and one was at only 50% (2 balls floating). The electrolyte level has always remained at the upper fill mark.

Obviously something is not right in the charging system but I am at a loss for what is causing this. Like I said; I am getting 15.4V output with the engine running at 2000 RPM. How is it then that the new battery is still requiring a ten to fifteen minute charge after a ride?

How can I tell whether the problem is the charging system or the new (bad) battery? Could a charging system problem have ruined the new battery?

 

Assuming you're getting 14.5 at 2K rpm (not 15.4) the charging system is fine.

Unless you come flying in above 2K rpm and kill everything before the engine slows down the battery will discharge a bit before you shut down. Not surprising that the maintainer will charge for a few minutes.

The specific gravity in the cells might be a different issue though.

 

I wouldn't worry about it. What voltage does the battery have after a long rest without a charge? Start riding and see if the battery goes flat. The alternator appears to be doing its job fine.

 

your tender might be off just a bit too.
read about charging at batteryuniversity.com
how long was your charger on before you checked the specific gravity

 

It's fine. At idle, it's 12V because you're reading the battery. There is no output from the charging system at idle, the bike is running off the battery. That's normal.

I'll bet if you simply disconnect the battery maintainer for a day, with the battery out of the bike, just sitting there; then reconnect it, it will show "charging" for about 10 minutes too.

As Carl said though, you'd have to shut off all electrical consumers as the bike dropped below 2200rpm to not use the battery after a ride.

Get a cheapo specific-gravity tester from the auto parts and double-check the battery, so you can quit worrying about it.

 

seems obvious i know, but it's screwed me up before. Is ground wire to frame good and cleanly attached? it might LOOK fine but I've found a good sanding and a good new steel fastener can make a diff. Amazing how important a good ground is.

 

Not sure what type of charger you are using. The Battery Tender (trickle charger) that I use runs through a 'diagnostic' cycle prior to starting the actual charge.

This means that when I connect it, even if fully charged, the light is red while the diagnostic is running. I have never timed it but for at least 60 seconds the light is 'indicating' a low charge on the battery while it runs through a series of tests.

Good luck!

 

Have a very-close look at the Quick-Connect Plugs that join the Voltage Regulator to the Wiring Harness.

Look for obvious signs of overheating. (Melting)

Make sure ALL the Terminals within the Plug-in are fully depressed into the Plug.

Your 1,5 Amp Trickle Charger may not be adequate to give the Battery a DEEP Charge.
You need to 4 to 6 amps

http://www.sears.com/gl-2amp-6amp-dual- ... ockType=G1