I recently purchased a Jan 2006 vintage E-Max Sport. After about 10 miles of good performance, I managed to break something by attempting a standing start up a grade while overloaded. I'm a reasonably good mechanic, but don't have much experience with AC motors and electronic controllers.
I have the shop manual, if it can be called that, it's abysmal. I'm interested in fixing my E-max, but I'm also interested in compiling or writing better troubleshooting documentation for other E-max users, as it's obviously needed. I'm also interested in some of the mods I've seen here, and willing to compile a single reference document for this info so it's a little more accessible.
Any tech help troubleshooting would be much appreciated, and shared with the E-Max community.
Loud "knocking" sound from the hub motor on starting and cruising. Louder under high
In some positions (rolling back and forth), no motive power, just a "grinding" sound.
For both of the above symptoms, it feels a lot like a stripped gear tooth, although there
are of course no gears involved in the E-Max hub motor.
Fairly severe vibration when running under no load (up on center stand).
Reduced power (approx 1/2 - 2/3?).
The shop manual lists five possible causes for the symptom "The motor makes a loud noise":
Wheel bearing bad
Rotor grinds on cover
Loose magnet(s) in motor (manual calls this "alnico")
Motor cover is misaligned
Hall effect sensor defective
I pulled apart the motor, and am convinced that the problem is not due to any of the first four causes. I did find an old quality control sticker (!) riding around between the rotor and hub, but removing it didn't fix the problem.
The manual's troubleshooting technique for the Hall Effect sensor is less than illuminating, but from my tests with a voltmeter, it appears to be working. The "timing" could be off, don't have a good way to test that yet. The sensor wasn't loose or misaligned as far as I could tell.
I suspect that the trouble lies in the controller, probably one or more power transistors failed. I tried using the troubleshooting technique in the manual and did not get values in spec, which would confirm this. Caveat; some of those values are suspect, and the troubleshooting instructions are incomplete (sentence fragement at end of page).
I pulled the controller and opened it up, don't see or smell anything burnt. The 1000uf Capacitor #101 does have a large dent in it, but that looks like something that must have happened during or prior to installation.
This is a "new" style controller with the large 5-pin threaded collar and E-Max badge.
Here are the volt/amp/ohm readings I collected from the controller:
Black/Red - 50.0 volts
Yellow/Green/Blue - varies with position of motor, appears to be at regular intervals throughout 360 rotation.
Black/Red - unstable readings. Starts at about 4.6 ohms, drops down past 1.0
Black/Yellow - open
Black/Green - open
Black/Blue - open
Yellow - 2.18
Green - 3.05
Blue - 4.88
These readings indicate a fault in the controller. Although I have opened the controller, I don't have a good plan to test individual components, so any specific help here would be much appreciated.
One more piece of probably unrelated information. Although I never tested it fully, Joe told me the one or more of the batteries were suspect and that this scooter had limited range. This problem appears to be distinct from the current "shuddering" and "knocking" problem as i did not have any problems for the first 10 miles of operation.
Guineng Battery voltages range from 12.60 to 12.89.
Odometer reads ~350, and the overall condition of the scooter conforms with this; it's in good shape and everything else works fine.
Anyone with troubleshooting tips and/or known good circuit specs - voltages and amps, your help is much appreciated. Like I said, I'll take the time to write them up and re-post a comprehensive troubleshooting guide for everyone's benefit.