Stator or Something else?

[Steve NZ]

Hi forum..
I've been having some charging issues and they seem to be pointing to a dying stator,
though, I'm hoping thats not the case.  :(

So I'm bringing it to you, for the final verdict.

The Battery has died twice now. =(

Charged, the battery is reading 12.5 on the volt meter.
however as soon as I connect the terminals, (with the the bike off) the reading drops to 12.
With the bike idling, the reading still stays at 12, but will climb to 13 volts if I rev the engine.

Over time, (few days) the voltage slowly drops to the point where it can't start the motorcycle.

With the bike idling, I removed the positive terminal from the battery and the bike died instantly.
As far I know this is an indication of dead stator or rectifier, but it could be an old wives tale.

As I only have a very simple voltmeter, I'm at loss for ideas of more tests.

Does this point to what I fear? I dead stator?

:-\

[Steve NZ]

... ?

[Tiger]

 :) I don't think its a stator, not if you can go from 12 to 13 volts when running, (With the bike idling, the reading still stays at 12, but will climb to 13 volts if I rev the engine).

The loss of voltage, when switched off, points to a short somewhere in the system...(Over time, (few days) the voltage slowly drops to the point where it can't start the motorcycle).              8).......TIGER........ 8)

[Lucky]

You cant guess with this..you have to charge the battery up then do the proper tests FULLY:

http://www.electrosport.com/media/pdf/fault-finding-diagram.pdf
and
http://www.xz550.com/RRTESTS.jpg

--Lucky

[fret not]

How old is the battery?  Can you see any white areas on the cell plates?  The battery is a key element in the system and nothing will work correctly if it is not in good health.

This is a great time to clean and grease all the connectors so you know you have good electrical contact.  Especially make sure your battery leads are clean and making good contact. Also check the condition of the battery cables near the crimped fittings, as sometimes they corrode inside the insulation sheath.

Your next check might be the output of the stator.

Go to the xz550.com/RRTESTS page and follow the instructions for testing your regulator rectifier.

[Rikugun]

As Lucky points out, a careful diagnosis is in order as outlined in the link.

Just based on what you've said, it could be a combination of failing battery, stator, and rectifier! This leaves lots of room for guessing!

A fully charged battery should be slightly over 13v, not 12.5. In addition to voltage, testing the acid's specific gravity is a  great test. Unfortunately, finding a hydrometer with such small volume requirements for small batteries is tough. Without a fully charged battery, you may as well not perform the tests as the results may not be accurate.

It's interesting the voltage drops when connected to the bike and continues to drop over time. It may suggest the rectifier is "leaking". There are tests outlined in the link to check the reverse bias leakage of the rectifier's diodes but not all meters have that function or the proper range. Another method is if your VOM (volt-ohm meter) has a mili-amp setting. Connect your meter in series with the battery ground and ground cable and check for flow with the key off. If no amp function is available, charge the battery but don't connect the leads. If after sitting for a few days the voltage doesn't drop, or drops less than when connected in the bike, I'd suspect the integrity of the rectifier.

I wouldn't suggest removing battery cables while it's running. Rather, test the stator using the static tests outlined (proper resistance of the stator coils/not grounded) and the dynamic running test for AC output.  Good luck with it.

[jasonm.]

past 30+ years I have never had a battery that if fully charged and rested for a day, read more than 12.9v. And that is an expensive AGM battery. Lucky I believe is refering to a rested battery (aka sitting for a few days)...NOT just charged up recently...aka within past 2 hours.  . If it's below 12.5...start looking for a BATTERY ...especially if it's over 4 years old. I get minimum 5 years out of my batteries. One lasted 9 years. And only went bad because of a "diode" that slowly drained it. Don't ask...  Steve, I would start with a NEW BATTERY. I know right after charging it should take days for it to drop below 12.7v. UNLESS it's bad.  I did have a bad rectifier once, that only charged to 12.8v. Which was enough to get me home.