2017 RC390 Battery not charging

naveed

Member
My motorcycle died on track at a very high speed and I think it is due to the charging system failure. I have antigravity Lithium Ion battery that cuts off the power when the voltage drops below a threshold. I charged the battery and started the bike, the battery continues to drop the voltage and eventually the bike dies. I put external charger on the battery and started the bike and the bike does not die. I also confirmed that RC390 dies as soon as the battery is disconnected. The voltage at battery terminals keep decreasing even when the bike is running.

I was wondering if anybody has similar experience and how should I approach the problem. Do I need to replace the stator, voltage regulator, or both? Do I need to open the engine to change the stator?

I would be grateful for any help.
 
Naveed,

I can't claim to have encountered this problem, but based on your checks to this point, my best guess would be the charging system. But first, a few other things to consider:

-How old is the battery? Is it near the end of it's life? Do you have another battery you can try? Perhaps the old lead/acid, if you kept it?
-Do you have any added electronic accessories that may be draining power? Phone Charger, ant-theft system, tender leads, etc.? Seems unlikely this would cause your problems unless they were faulty, but it'd be a good first check to disconnect any electrical accessories and see if the problem continues.

If that all checks out, then you can check the stator by doing the following:

-Locate the 3 pin connector that connect the stator to the rectifier
-Check the resistance between every pin combination (1-2, 1-3, 2-3) - All of these should be less than 1 ohm (from repair manual).
-Check the resistance between all pins and the negative terminal on your battery. All should read Infinity or OL. If it doesn't, then your stator is grounded.
-If the above checks out, start the bike, hold it at 4k RPM and measure the voltage between every pin combination. All readings should be above 50V.

If any of the above tests fail, then you need a new stator. If everything checks out, your stator is probably fine, and the issue has been narrowed to your rectifier/regulator or your battery (if you didn't have an extra to test previously). I'm not sure how to go about testing the rectifier, so perhaps someone else can help with that. The first thing I'd do is resistance check the cables coming in and out, and see if you can measure a voltage out. You already checked that you're getting your 50VAC in, so my next step would be to make sure I'm getting DC out. I would expect this should be around the battery charging voltage (13.5-15V), but I'm not positive. Either way, if you or a friend have another bike/battery, I'd see if your battery works in another bike, or see if you encounter the same issue with another battery in your bike. Either of these would suggest that your battery is fine and you need a new rectifier.

Hope this helps. I'm not an electrical engineer, and electrical issues are not my forte, but I'm doing my best. Let us know what you find.
 

naveed

Member
Thanks a lot man! I figured it out the other day. It was in fact the problem with the charging system. I installed Powertronics ECU, unplugged alternator battery charing connector and forgot to put it back. It was so frustrating, such a simple thing ruined my two track days.

I was looking for that 3 pin connector so I can check my rectifier, but couldn't find it. Do you know where is it located? Is it near rectifier? I wanted to check my alternator to make sure it works fine.
 
I'm not actually sure where it physically is on the bike, and that may vary by model year anyway, but It'll be where the stator connects to the voltage regulator/rectifier. So I'd start at one of those and work your way toward the other until you find a connector. There should only be one line in between, and the connector (at least according to my 2018 manual) looks like the image at the bottom. But, if your battery is now working, the quickest to verify your alternator is working properly, would probably to measure the charging voltage at the battery. Steps below:

-With the battery installed, connect your multimeter (verify you're getting the expected 12-13V)
-Start the bike, rev to 5k RPM and make sure the voltage is between 13.5V and 15V (charging voltage)

If you're getting the 13.5-15V, then you can be confident that your charging system is functioning properly. No need to strip things off to find that connector. If you fail the voltage test, then the checks in my previous post would probably be the next step, but it sounds like you're probably fine. At least forgetting to mate a connector is a hell of a lot cheaper than replacing a stator or rectifier.

Stator Connector.jpg
 

ReidMcT

Member
Premium Member
Elite Member
Site Supporter
I was looking for that 3 pin connector so I can check my rectifier, but couldn't find it. Do you know where is it located?
It is a medium pain to access. It is located under the battery box and fuel tank. At a minimum you would been to dislodge those two components from their mountings in order to be able to put your hands on the connector, which is fastened to the frame just aft of the steering head.
 

ReidMcT

Member
Premium Member
Elite Member
Site Supporter
It had the fairings off today, so I took a photo from the right side, showing the regulator/rectifier as well as a partial view of the 3-pin plug where you can access the three yellow alternator wires.RC390 RegRect w Alternator Plug.JPG
 
Top