charging at 12.2-12.4 . . .. not 14.5? please help

[walden22]

Okay.
Bike is a 81 special. I know just enough about electrical to get myself in trouble. Bike has 1,500 miles on it total so no electronics should be worn out. I preface with, I have done fair amount to forum searches and read through many pages of info, tried to duplicate their tests. Still cannot find problem.

New battery in bike and it was charging at ~14-14.5v while running with rpms up
About a week later and about 50-100miles ridden It now shows 12.00 at idle and 12.2-12.5 when its at 3000+RPM. SO its charging... but not really.

What I have done to check.
1) removed battery and charged overnight to full (same results
2) checked ohm readings on slip rings - all zero out. good.
3) cleaned brushes
4) put in a spare regulator/rectifier i had (same results)
5) cleaned the terminals on reg/rec plugs. (all others looked good)
6) threw hands in air and wrote this thread.

Questions - - is it possible for a new battery to read correctly on week and then limit charging v the next? Is it the battery? (please be this easy).

Any other ideas what would cause a 'low charge' condition with parts that are working one week, not the next and all are very 'new' (low miles).

 

[5twins]

It's not so much the low mileage but rather the age of the components. They're old enough that any could go at any time. You didn't mention cleaning the slip rings. If they get dirty enough, that can limit the connection between the brushes and rotor. A little metal polish of some sort works well. Here's mine with one cleaned (outer), one not (inner). I just used a little chrome cleaner on a rag .....

 

[walden22]

@ 5twins

I didn't polish the rings, but i did clean thing off with electrical parts cleaner which made them quite shinny. I will pull the cover again today and polish.. see what happens. . maybe swap with another bike battery i have for laughs.

 

[5twins]

I don't think the battery itself would limit the charging system output. A fully charged one may lessen it somewhat but a fresh start with the electric starter usually pulls the battery down and results in a pretty good charging system output, at least for a while until the battery recovers its lost charge.

 

[retiredgentleman]

"checked ohm readings on slip rings - all zero out. good"

What does that mean? Slip ring to slip ring should be around 5 ohms.

Brushes should be at least 3/8" long, if shorter, you must replace.

 

[5twins]

Yes, if you're reading zero ohms between the slip rings then that's probably the problem, you rotor has gone bad.

 

[walden22]

Yes, if you're reading zero ohms between the slip rings then that's probably the problem, you rotor has gone bad.

Okay - Update on headache.

Trial 1 - Took apart again, this time, polished the slip rings. Then I tested the resistance between the rings. Here are results. Photos below as I might not be using this meter correctly. Let me know.
Both contacts on outer ring .4 ohms, both contacts on inner ring .4ohms, Resistance between inner and outer right 1.5 ohms ??? should be 5.... am i using this wrong?

Trial 2 - put all together again - and ran with the 'possibly bad brand new' battery with the same 12v idle and 12.5ish with 3-4k rpm. Then I swapped out for another battery I have around and it ran 12.8 idle and 14.5 with 3-4k rpm... which is what it should read.

OKAY - so does this mean that it's simply a 'lemon' battery that is incapable of taking a charge over 12.5v or does this mean that my rotor is bad since it's numbers are off (or I don't know what I am doing).
See bunch of photos below showing how shinny new everything looks but is not

This is how it looked without any cleaning...

After polishing slip rings

This is before cleaning.

 

[retiredgentleman]

Your rotor has an intermittant short circuit. It must be rewound or buy a new rotor.

 

[walden22]

Your rotor has an intermittant short circuit. It must be rewound or buy a new rotor.

So am i using the meter correctly and its just reading 1.5 where it should read 5?

Also doesn't explain the battery issue. How it charges correctly on one battery but not on another (both are new). . .

I'd rather have my new battery swapped out under warranty then spend another 100 on this bike.

 

[walden22]

Yes, if you're reading zero ohms between the slip rings then that's probably the problem, you rotor has gone bad.

Picked up a 'new' new battery today and it reads the proper 14.5 while running under rpm...But now you all have me concerned that my rotor is bad since the slip ring readings are not right? 5twins - am i using this meter incorrectly in the photos. Im really hoping so, otherwise i guess i need a rotor... :bang head:

 

[walden22]

I read this http://www.650central.com/fso_your_bike_chokes_off_at_stopl.htm

And looks like what I am afraid to admit. My shiny clean, 1,150miles total on bike rotor is bad. . . retiredgentleman .... must be intermittent like you said, and coincidental with the new battery I just put in. IDK have no other rational ideas.

LOL. man I better be keeping this bike a long time. So please point me to the best source for a new rotor that works with the TCI. I'm half way digging to the country this bike was made, may as well keep going

 

[nj1639]

Check out this thread.....

http://www.xs650.com/forum/showthread.php?t=17412&highlight=Custom+rewind

 

[retiredgentleman]

Picked up a 'new' new battery today and it reads the proper 14.5 while running under rpm...But now you all have me concerned that my rotor is bad since the slip ring readings are not right? 5twins - am i using this meter incorrectly in the photos. Im really hoping so, otherwise i guess i need a rotor... :bang head:

According to your ohmmeter readings, the rotor is bad.

However, if your voltmeter shows 14.5 volts, then that means the rotor is good. You could try riding your bike for a few days/weeks, and see what happens. If its intermittant, then you will soon have no charging.

There's a reason that quite a few of us have a voltmeter installed on our bikes. The voltmeter gives early warning of any alternator trouble.

 

[walden22]

According to your ohmmeter readings, the rotor is bad.

However, if your voltmeter shows 14.5 volts, then that means the rotor is good. You could try riding your bike for a few days/weeks, and see what happens. If its intermittant, then you will soon have no charging.

There's a reason that quite a few of us have a voltmeter installed on our bikes. The voltmeter gives early warning of any alternator trouble.

Agreed. BTW - what analog voltage meter do you have? I'm trying to avoid a digital one to keep with the period correct feel/look.


Also---anyone.. looking at Custom Rewind as a place to get a new rotor,,,, but they did not answer phones or emails the last two days, hmm... tick tock as the short summer in CT is passing me by. grrr!!!

 

[nj1639]

See if this works......

Ah yes.
I get mine at Tractor Supply, around $15 some years ago. I relocate the ignition switch to the right hand side under the tank and also move the indicator lights to the tach bucket. The stock indicator light support tree can then be trimmed down and the voltmeter bolted directly to the trimmed tree. IIRC there are holes there that work perfect.
It gets pretty involved but it's what I want. That tach in the pic is from an SR500, the one on my '77 is the stock tach but with lights, lenses and light tubes installed. You'ld have to disassemble one to understand their workings.
RG has a nice setup by adding a support for the voltmeter, less involved and still maintaining the indicator tree.

 

[retiredgentleman]

I have my voltmeter attached to the handlebars.

 

[walden22]

See if this works......


Ah yes.
I get mine at Tractor Supply, around $15 some years ago. I relocate the ignition switch to the right hand side under the tank and also move the indicator lights to the tach bucket. The stock indicator light support tree can then be trimmed down and the voltmeter bolted directly to the trimmed tree. IIRC there are holes there that work perfect.
It gets pretty involved but it's what I want. That tach in the pic is from an SR500, the one on my '77 is the stock tach but with lights, lenses and light tubes installed. You'ld have to disassemble one to understand their workings.
RG has a nice setup by adding a support for the voltmeter, less involved and still maintaining the indicator tree.

Thank you for sharing this!!!.. definitely doing what was done in this photo. I very much dislike the stock indicator light tree. This is far cleaner.

 

[walden22]

Ordered a rewound router from Kirk at Custom Rewind. Really nice guy to talk to on the phone. Said their rotors run 4.6ohm since they are wrapped heavier than stock to charge a little lower rpm. lets hope so.
will let you know how this all pans out.