Bad stator?

[joewillybob]

I'm having charging issues on my 71 T500. Testing the input to the battery results in appox. 10 volts. Testing the stator as per the shop manual, the test that you run between the red/green and the yellow/green wires results in appox. .9 ohms. The book says it should read .6 ohms. Since I know virtually nothing about the mysteries of electricity, is the difference between .9 and .6 enough to cause the low voltage problem? I've checked the regulator and the rectifier according to the book and both test out fine. Also, there is a light film of rust on the outside surface of the rotor, and also some rust on the stator coils. Is this part of the problem? Do I need to lightly sand off the rust? Thanks.

[jabcb]

Does the alternator output problem occur when you have (1) the lights switched off, and (2) the lights switched on?

Wiring diagram is here: viewtopic.php?f=29&t=4743

Alternator spec s are on page 15 of: h[url]ttp://www.ozebook.com/compendium/suzi/suzidata1.htm[/url]

The T500 alternator has 3 wires: Y/G, R/G & G/W
stator Y/G connects to rectifier Y/G
stator R/G connects to rectifier R/G (for charging coil)
stator G/W goes to light switch, switches to R/G, light switch R/G connects to rectifier R/G (for lighting coil)

To check stator resistance:
Unplug the alternator connectors from the rectifier & wiring harness.
Then:
1) check resistance between G/W & Y/G wires, should be near zero ohm
2) check resistance between R/G & Y/G wires, should be near zero ohm
3) check resistance between one of the wires & ground, should be open circuit

The resistance reading you get is the wiring resistance plus your meter's internal resistance. Touch the meter leads together to get the meter's internal resistance.

To check stator output:
Unplug the alternator connectors from the rectifier & wiring harness.
Set multimeter to 100V AC.
Then perform these test with engine running:
1) check voltage between G/W & Y/G wires, should get something like 40V depending on rpm
2) check voltage between R/G & Y/G wires, should get something like 40V depending on rpm

[joewillybob]

Thanks for the help.Checked the resistance and connectivity as suggested. Pulled the stator to check the lead wires. Everything seems ok. Only issue is about .4 ohm resistance between r/g and y/g wires. Put everything back together and checked the output . Over 40 volts at just above idle. Plugged everything back together and now everything checks out. About 13 volts at idle with the lights on. Must have been a faulty/corroded connection somewhere. Thanks again for all the help. Now, if I could only get the carbs sorted!

[Fritz500]

Guys I need an opinion or three....

I flattened my battery after a recent night ride. Decided to check the alternator:
(The resistence values are after meter's internal resistence has been allowed for)

• resistence between G/W & Y/G wires was 0.9 ohm (should be zero)
• resistence between R/G & Y/G wires was 0.6 ohm (should be zero)
• The voltage between the G/W & Y/G wires was 35v (should be aound 40V) at 2,500rpm
• The voltage between the R/G & Y/G wires was 40v at 2,500rpm

What would cause the alternator coil resistence to be above zero? I bench tested the coil from my other T500 and the coil showed a resistence of 1.3 ohm and 0.7 ohm.

Thoughts?

Cheers

[jabcb]

The spec of "nearly zero" ohms was written back in the 70s for analog multimeters that were pretty meager by today's standards.
You should measure a small resistance.

Also check the resistance between each wire & ground. You should get an open circuit.

Is your bike charging properly during the day with the lights off?
What headlight wattage are you using? (stock or did you upgrade)

[Fritz500]

jabcb,
I thought so much - I'm now happy with less than an ohm.
Yes got an open circuit reading for each wire.
I'll check the charging again tomorrow. I tested it a month ago and it didn't seem to be charging even with the lights off.
Standard headlight - no mods to anything on the bike - all standard.


More info to follow.

Thanks

Geoff

[Fritz500]

Tested the bike again today.

With the ignition turned on the bike pulls about 2.3 amps.

With the motor idling at 1500rpm it pulls about 1.4 amps

With the motor spinning at 2500rpm (and up to 4000) it still shows 1.0 to 1.1 amps. The voltage across the battery shows 11.7 volts under the same conditions. I'm going to swap over the voltage regulator with a spare I have.

Cheers

[jabcb]

Looks like your alternator output is about half of what it should be. That points to the rectifier as a likely problem.

If a bad rectifier is rectifying only 1/2 wave rather that the full wave, you get half the output.

Now might be a good time to update the electrical system rather than repair it.
You can get a good rectifier/regulator for about $50.
It replaces both the rectifier & voltage regulator, and provides a smidgen more output than the stock parts.
A modern regulator/rectifier also provides much better voltage control.

[Fritz500]

jabcb,
Can you recommend a few of these voltage rectifier/regulator combos?

Thanks

Geoff

[jabcb]

I like the Tympanium regulator/rectifier for the T500.
This is how its installed on my T500: viewtopic.php?f=2&t=4858&p=109480&hilit ... um#p109480

Its available from eBay for about $50
http://www.ebay.com/sch/i.html?_nkw=tympanium+triumph" onclick="window.open(this.href);return false;

Oregon Motorcycle Parts also has a good rectifier/regulator for the T500, part # VRRPM2.
Its $92. Has higher output capacity than the Tympanium but its not as easy to install.
http://www.oregonmotorcycleparts.com/VRRPM.html

Several companies sell rectifier/regulators that look exactly like the Typmanium.
Don't know if they are rebranded Tympaniums or clones. Have one installed on another bike & it works fine too.

Not sure what is easily available in Australia.
Its needs to be for a single phase, permanent magnet alternator.
It should have two yellow wires; if it has three yellow wires than its not suitable for the T500.
Post the links if you find anything more readily available.

[Fritz500]

Finally found the problem.

Swapped the rectifier with a spare one and it made no difference though I do believe there is a problem with one of the diodes in the old old. I'm going to spend some time testing it tomorrow. The swap made no difference to the current or voltage measurements from my previous posts.

I then swapped over the voltage regulator. Bingo! Watched the voltage rise from 11.7 to 12.9 in just short time. The amps went from the previous battery draining -1.4 amps to a charge rate of nearly +2 amps at about 2500 rpm.

Once the battery gets fully charged I might measure it all again with the headlight on too.

Night rides here I come.

I may still buy an aftermarket set-up and keep it for the next failure.

Cheers to all the kind folks who have assisted me. Always appreciated.

[jabcb]

Having two concurrent problems can make it a bit more tricky to figure out.

Have a 45/45W H4 halogen headlight on my T500. Definitely a useful improvement for night rides.

A modern rectifier/regulator like the Tympanium provides a smidgen more output than the stock parts.
Have also upgraded to an AGM battery.
I have the headlight on all the time & do mostly local riding. This combo has been working fine for a few years.

The H4 headlight + mounting hardware + rim is from a GS series bike & fits the stock T500 headlight bucket.
Let me know if you are interested in this upgrade -- I should be able to figure out which GS-series bikes the headlight is from.

[ConnerVT]

The H4 headlight + mounting hardware + rim is from a GS series bike & fits the stock T500 headlight bucket.
Let me know if you are interested in this upgrade -- I should be able to figure out which GS-series bikes the headlight is from.

I think that this will only work if you have a later model T500 headlight bucket, yes? The earlier ones (as on my '71) have the flat bottom lens.

What I went with was an after market bucket assy (Emgo 66-64312) that I picked up on eBay. It is very similar to the stock assy, and fits wonderfully. The backside is shaped to allow all of the cables/wires to fit without an issue. New chrome, and clear un-fogged lens is certainly a plus. It came with a 55/60W H4 bulb, which I replaced with a 45/45W.

I got mine from these guys, and with an additional bulb, set me back only $75 USD. Looks as there are shops on all of the continents that sell it for about the same price.

[jabcb]

The H4 headlight + mounting hardware + rim is from a GS series bike & fits the stock T500 headlight bucket.
Let me know if you are interested in this upgrade -- I should be able to figure out which GS-series bikes the headlight is from.

I think that this will only work if you have a later model T500 headlight bucket, yes? The earlier ones (as on my '71) have the flat bottom lens.

What I went with was an after market bucket assy (Emgo 66-64312) that I picked up on eBay.

Oops.

You are right about the early flat-bottom headlight. Joewillybob's T500 is also a 1971 model.

A plus for the Emgo headlight is the large opening in the back for wiring. Makes it much easier to feed the electrical connectors & wires into the bucket.

[rocc99]

@jabcb - Do you know if the Tympanium regulator/rectifier that you provided a link for will also work for a T350? I am having the same issue as the OP, getting zero charge to the battery.

I haven't gone through all the steps to determine the culprit yet, but I figured I'd check to see if the regulator/rectifier you named would work for me as well, if that ends up being the issue. Here's the one I found on ebay:

http://www.ebay.com/itm/NEW-Tympanium-V ... 9c&vxp=mtr" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

I have the service manual, so I'm hoping between that and this thread, I should be able to determine the problem. Any other tips you might have are always appreciated though. Thanks.

P.S. - just noticed your from SWPA - Pittsburgh local here...