Bandit 400 AC Generator tetst

[bdouvill]

Hi guys,

Sounds like my battery is not charging anymore when I run my B400 so I ran the tests indicated at page 6-3 of the service manual.
Standard charging output is only 12.6 V so below the correct range (13.5 to 15.5) so that confirmed the charging system is faulty.

AC generator no-load performance test is quite easy but I'd like anyone to confirm (who said greg737?). Around 5000rpm with high beam on, the AC voltage is around 80-85V between all 3 pins. According to both the French and the English version of the Service Manual, any voltage > 70V means the generator is faulty. Is that correct?

I hated electricity when in College. Any explanation why a faulty generator seems to produce too much electrical power? I would have guessed not enough power is faulty, not the opposite.

For info, I started by replacing the regulator which has over 80 000 km with another better looking one coming from a bike with only 45 000 km. My Digital multimeter is not able to measure any of the resistance indicated at page 6-4 of the service manual. I checked the resistance range was correctly set, I see no explanation for that.

Many thanks in advance to help me understand how this works.
Regards.

Benoit.

[greg737]

Have you searched the internet for a video of the tests?  I like this guy, he's very direct, plainspoken.  It's english though, hope that's not a problem.  He walks you through all of the testing and he gives you electrical system information at the same time.

You should watch this one.  He spends the first 5 minutes giving you motorcycle electrical system "wisdom" then during the remainder of the video he shows you how to test the components.

http://www.youtube.com/watch?v=44hLjPBObYw

You know you're listening to a person who understands motorcycle electronics when, before he talks about the tests, he starts out by pointing out how easy it is to mis-diagnose motorcycle electrical problems and also by talking about how common it is for corrosion in the connections to cause problems.

[greg737]

According to both the French and the English version of the Service Manual, any voltage > 70V means the generator is faulty. Is that correct?

No.  You read it backwards.

According to the manual you want to see more than 70V (AC) at 5,000 RPM.  You want to see >70 on each phase of the alternating current that the generator puts out when the engine is running.

So it appears from your test results that your Bandit's generator is in perfect condition.  Your problem is somewhere else...

[greg737]

So your generator is good, your test proved that.

Now you carefully check the wiring and connectors that link the Bandit's Generator, to the Regulator/Rectifier, to the Battery.  Check for good condition: no cracks or cuts in the insulation, no corrosion on the connector spades, no obvious heat issues like melting of the plastic connector housing.

Then you go back to testing, this time you'll be testing the Regulator portion of the Rectifier/Regulator.

The Rectifier portion of the Rectifier/Regulator won't be your problem, this portion never fails.  It just sits there doing this (which is an easy job in the electronics world):



If you've got a problem with your Rectifier/Regulator it will be in the Regulator part.  The Regulator has to take that rippling 20 to 35 volt DC power that the Rectifier creates from the generator's output and "waste" it down to the 13.5 to 14.5 volts DC that a Sealed Lead/Acid Battery (SLAB) likes to get. 

This qualifies as hard work in the electrical world because to do it the Regulator has to turn the unwanted electrical power into heat to "waste" it away (this is why the R/R has aluminum fins on it).  Heat is hard on electrical components.

When Regulators go bad it is usually a failure of the ability to waste excess voltage that allows the Regulator to send out DC power that is higher than 14.5 volts which will, over time, ruin the bike's SLAB.

But you're saying this:

Sounds like my battery is not charging anymore when I run my B400 so I ran the tests indicated at page 6-3 of the service manual.
Standard charging output is only 12.6 V so below the correct range (13.5 to 15.5) so that confirmed the charging system is faulty.

So I'm wondering what might cause that issue.  Maybe some sort of parasitic electrical draw situation?  Has your Bandit's wiring harness been modified in any way?  Have any electronic components been added?  Has any of the wiring been re-routed or re-worked in any way?

[bdouvill]

Hello Greg,

Thank you so much for all that information 

First, I read again the manual and this is now clear to me that more than 70V is the standard (ie normal) behavior for the generator. I also made the continuity check yesterday and it was ok.

Second, the regulator. I'm a little bit embarassed with the test proposed in the manual. It says that results will defer another ohmmeter than the Suzuki one and this seems true. With my digital multimeter, I can not measure any resistance for my 2 regulators :-(

About the wiring harness and the connections, here is some information. I have nothing fancy on my motorcycle, only standard afetrmarket turning signals that respect the original connectors. But I may have a lead.

When I first got the motorcycle, I noticed a terminal strip on the main harness but I never check what it was used for (that was 4 years and 14 000 km ago). When I decided to switch the 2 regulators yesterday, I found that it was used to link the main harness and the regulator... The original connector is no more present on the harness (which explains the use of the terminal strip). My newer regulator has the connector so I put 2 spades connectors on the harness to replace the strip.

The fact you mentionned to check general condition of the wiring make me think about that:
- when I put the spades on the main harness, the copper wires were greasy. I did not cut more because the harness was "blocked" by the tank (I did not want to remove it at that time).
- I know that my tool to fasten the spade connectors is not a professional one and the connections are not really reliables (they do not resist to traction for example).

I believe I would be more inspired to find my extra harness in my basement, cut the connector and solder it on the one currently on my bike. I have no soldering iron but it might be a good Christmas gift to myself :-) Do you think a loosy connection between the regulator and the main harness (so to the battery according to the electrical schemes in the manual) would explain the result of the load test?

I never switched the whole harness with the other one which is in a better condition because I believe there are some differences in the harness between 1991/1992 models and later models. Can anyone confirm?

[interfuse]

This solved my low charge issue

http://forums.banditalley.net/index.php?topic=12930.msg101959#msg101959

[bdouvill]

This solved my low charge issue

http://forums.banditalley.net/index.php?topic=12930.msg101959#msg101959

This seems like a +1 on the loosy connection ;-)
I let you know when I can work on my bike.

[interfuse]

Just to confirm, in my situation it wasn't a bad connection. It was a bad wire. Here's a write up that explains it better then I did.
http://www.advrider.com/forums/showthread.php?t=719093

[bdouvill]

Interfuse got it! Thank you very much 
New copper wires able to support 20 Amps, a fuse holder with 20 Amp fuse, et voilą: 14.95V instead of 12.60V
No comments.

[greg737]

While disassembling and rebuilding my Bandit 400 I was impressed by some of Suzuki's engineering, but there where a couple of things that surprised me. 

One thing that seemed a bit odd was some of the wiring, especially the way power supply was routed through the bike.  And I agree that the gauge size of some of the wiring (in the power supply portion of the loom) seemed a little undersized.

[bdouvill]

Thanks again to both Interfuse and Greg for their tips and the time they gently spent to answer my questions.
 

[interfuse]

You're welcome. Hopefully it saved you some head scratching. It took me awhile to figure that out.