Problems with charging the battery

Hello everyone.
My name is Andy and I live in Switzerland. Since my English is not so good, I had Google translate it:
But now to my problem: I bought a Silverwing 400 about 1 year ago. This was built in 2011 and already has 63,000 kilometers on the odometer. He drove without any problems in that one year. Now on the last tour I had the problem that the battery was no longer charged and the scooter would no longer start. I then bought a new battery, but the problem reappeared. When I got home, I took care of the problem. Various measures and tips were given on the Internet. So the first thing I did was measure the voltage across the battery when the scooter is running. This is approx. 12.8 volts. The voltage does NOT change when accelerating! It was advised to replace the voltage regulator. I did this. Unfortunately no success. Now I am recommended to replace the alternator. But isn't it the case that the control lamp in the cockpit has to light up when the alternator is defective? I also checked everything with the digital multimeter, everything was within the specified values. Also the resistances at the collectors and the voltages... Can you give me a tip on what I can do or why? Before I replace the alternator and spend money unnecessarily again, I would be very grateful for a hint. I know that this is only a forum for the 600 SiWi, but I can't get any clear statements on the Internet. First of all thanks for your answers and efforts. Kind regards, Andy

Welcome, Andy!
Someone will help solve your problem for sure.

The first thing to check is your common frame grounding point, place scooter on center stand, remove LH passenger footpeg assembly, remove two large Hex/Allen bolts, push top in to dislodge side cover pin and slide back (repeat for RH side for alternator coil check), in area behind cover, disconnect all ground wires from frame, clean all contacts and frame with wire brush or scotch-brite pad, alcohol, etc. reconnect, then coat with grease or a spray lubricant to protect from water.
 This charging system is fairly common to lots of motorcycles, you should see 14-15.5 volts at any rpm above idle at the battery, around 14.5 volt is ideal, the alternator check is fairly simple, in addition to shop specific SW600 service manual procedure that's fairly vague , there's a lot of YouTube videos that apply to this charging system. that show how to check all parts of system, well start with alternator stator check 1st, a bad alternator can damage a regulator, it should always be checked first.
Maybe you can use google translate, etc., on videos.

https://www.youtube.com/watch?v=BVXnbrigYf8 , https://www.youtube.com/watch?v=5v2LtHlvcqI

Thanks for the hint. I'll check it out in the next few days. Best regards

Hi Andy and welcome to the Forum!

My first thoughts on reading your post were, check the Alternator coil resistances 0.1 - 0.5 Ohms. As per zrx212 post.
If ok but your still only reading 12.8 volts @ the battery with bike running with the new voltage regulator, turn off and fully clean the earth wires at the voltage regulator and where they connect to the chassis, also the engines earth point and the battery earth common point.



As zrx212 explained the charging circuit is used in lots of bikes/scooters and the most common fault(when over 10 yrs old) is a bad earth somewhere in the line.
I also enclose the diagnostic from the manual. Hope this helps.



Be safe, be seen!

Thank you very much !!

There is a good fault-finding flowchart at Electrosport. https://cdn.shopify.com/s/files/1/1091/5694/files/fault-finding-diagram.pdf?235929069374954073

My guess is that your alternator has failed; I had the same problem on my 2001 Swing with 63000km. You can test this by disconnecting the 3 yellow wire connector and measuring AC voltage across any two pins while the engine is revving. You should see >50V across all pairs, if not the alternator will need to be replaced.

Hello everyone. Now that the weather is reasonably good again, I have the measurement results here. So the 3 yellow cables from the alternator all have 0.6 ohms between them. But all 3 yellow cables have continuity to ground (measured with the beeper). When the display reads "ohms" it reads 0.1 ohms to ground on all 3 yellow wires. When the engine is running and turning at 3500 rpm, 2 wires below each other show 50 volts, one wire shows 46 volts. So I think that the stator of the alternator is defective. Is that so? Best regards and have a nice weekend. andy

I wanted to ask if the stator of the Swing 400 and 600 are identical? There are so many offers on the web that also refer to the SW-T 600. Does anyone have the OEM number for the part? Many thanks.

The Honda original spare parts have the number 31120-MFT-642. The 31120-MFT-641 is crossed out. Do you know why? On the net I can only find the 641 as a spare part... Aren't these two identical? Where's the difference?

Hi Andy.

Using Honda UK parts listings 31120-MFT-642 is an updated part No. for 31120-MFT-641 listed as a 400 stator.
The 600 stator is listed as 31120-MEF-003 without change through the years listed.
I would be very surprised if they were different as Honda use one part fits all models. Just different prefix to denote the 400 from the 600. The manual makes no mention of the parts being different between the 400 and 600 stator.

Hope this helps in your search.

Be safe, be seen!

Hi JohnyC.
Thanks for the ifo. That helps me a lot in my search. Best regards.

A quick search on my side of the pond (US) shows that popular/quality/cheaper aftermarket replacement stators fit/compatible with all years/models of the Silver Wing 400/600. Don't know what's available in your country, but do the research before buying, etc.

PSA, is not that these charging systems are flawed, but the shunt regulator/rectifier (R/R) dumps excess power by grounding/heat. They also depend a lot on battery condition, 1. For a reference voltage 2. To dissipate some excess power. Anything that makes the R/R run hotter will also overheat the stator coil, keep in mind that stator is inside the engine because is "Oil Cooled", they run quite hot, the stator coils copper winding insulation "Usually" fails due to heat and/or age, it shorts to ground, sometimes there's a break in the copper winding due to heat embrittlement. I know lots of people subscribe to 'if it ain't broke, don't fix it', but installing an aftermarket "Mosfet" R/R is the way to go IMO, more efficient and saves other components in the system, is on my short list, for my scooters.