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[Phoenix13]

Hi all.

I recently purchased an Alibaba.com Chinese electric motorcycle from Wuxi Saichi Industries which I just received a week ago. It's a 10kw Yuma motor with an APT 72400 controller and a 72v80ah lithium pack in a metal case and a Chinese made BMS.  I am no expert on electric motorcycles but I have done some homework and understand the basics. 

There are three drive modes and reverse.  Sport, Drive & Park.  When using the Sport mode within 5 minutes of riding at speeds no more than 50mph in my sub streets, the bike power cutout and stopped.  It would not reset or come back on after waiting 30 minutes. I walked it back to the house and left it for the night.  The next day the bike power was working again due to nothing I did.  I took the bike out again to see if I could recreate the issue and sure enough it happened again after 5 minutes of running in Sport mode.  Once I got it back to the house I plugged in the charger and that reset the power immediately. 

Next I took apart the casings to look at the controller, wiring and battery to see if I could identify anything obvious.  Well, the controller is zip tied to the frame and some of the wiring looks a bit questionable.  I can see a sticker on the metal battery case that says 72v80ah but haven't pulled the case out yet. 

Next I jacked the back wheel up to run some performance tests to see if I could reproduce the cutout issue without riding the bike.    I ran the throttle on Sport mode at full speed 130kph for 5+ minutes on high with no issues.  I repeated this process several times and the bike would not cut power.  The controller felt cool as did the battery case and motor each time. 

My theory is that I am not putting stress and torque on the systems which may be what has caused the bike to cut power or overheat on my first road tests.  Not sure if it's the bms or controller.

I wasn't expecting to get Zero Motorcycle quality and had intended on upgrading things as I found the need to.  I may be here already at day one. 

I'll post some pics of the bike and systems to this post.  Let me know what you guys think I should do about the power cutoff issue and is there anything I could do to improve the current setup? 

I don't know much about the APT 72400 controller or if it is programmable with software (i couldn't find a manual online).  I also don't know if the bms is right for that battery. 

Any suggestions you experts can provide would be very helpful, to point a new guy in the right direction.  I'd be willing to upgrade parts if needed.

Thanks.

[TEV]

Could be:
1. the motor overheating.
2. The controller overheating.
3. The battery voltage sag under heavy load, but it should bounce back after a few minutes of waiting.

Does it displays the battery voltage?

What happens if you use "drive " mode ?

[Phoenix13]

I don't see the bms, it's in the battery case but I can pull it out at some point to see if it has a display.   The controller doesn't have a display and the cluster only shows battery bar, trip, odo and kph. 

Can you recommend a way to test?

[TEV]

You can connect a voltmeter to battery  + and battery  - at the controller.
With that battery pack,  I  will estimate 45 miles range at  30MPH, and a lot less in Sport mode or high speed.

How is the controller cooled?

[Phoenix13]

Attached photo is the current reading of the battery. 

The controller is not being cooled in any effective way.  It's zip tied to the frame under the casing and it seems that little airflow blow through it.  It doesn't appear to have a heat sink attached to the flat bottom and no thermal paste.  I may need to add a heat sink and mount the controller with better airflow. 

Others in another post are convinced the power loss issue I have experienced is due to the battery and that the bms is cutting the power.  They suggest it could be undervoltage and/or mismatched cells.  I will test the battery and see if the cells are mismatched.  I can use the cycle saturator to try and match the voltage of all cells from a full charge to see if that cures the perceived unbalanced cell problem.  I wrote the manufacture and they said there is a protection plate inside the battery.  They didn't want to call it a bms.  That could be part of the issue.   

[TEV]

The ideea with the voltmeter is to see what happens with the voltage when riding ( under the load)

My guess is that the controller is overheating . Try attaching  a heatsink and a fan.

[TEV]

Still didn't told me what happens if you use drive mode and ride at 25MPH without racing from traffic light to traffic light.

[Phoenix13]

I will run more voltage tests under load soon and post results.   I will absolutely add a heat sink and a fan with proper mounting of the controller this weekend.  Crazy they mounted it with a zip tie!

The ideea with the voltmeter is to see what happens with the voltage when riding ( under the load)
My guess is that the controller is overheating . Try attaching  a heatsink and a fan.

[Phoenix13]

I haven't road the bike more than two times because it cut power and I didn't want to get stranded again  .  However, I did notice the issue only occurred when I put the bike in sport mode and gave it a more throttle past 50mph.  It seem to have performed fine in Drive mode as the lower speeds.  Once I remount the controller I'll perform more road tests and see how it performs in less/more load scenarios. 

Still didn't told me what happens if you use drive mode and ride at 25MPH without racing from traffic light to traffic light.

[TEV]

LOL if you ride faster than 40MPH with that battery pack, even if the controller won't overheat, you're  not going to ride more than 10-15 minutes.

[Phoenix13]

I have no idea what the range of that pack will be.  I'm sure it's a cheaply made 72v80ah pack and if I'm already having issues at the beginning then your estimation could be correct.  The cells could be crappy unmatched 1C cells for all I know. I'll post my findings once I test the cell groups.

LOL if you ride faster than 40MPH with that battery pack, even if the controller won't overheat, you're  not going to ride more than 10-15 minutes.

[DonTom]

I have no idea what the range of that pack will be.

72 times 80=5.76 KWH. I would expect 50 miles at city speeds.

-Don-  Yuma, AZ (RV)

[Richard230]

There are more than one YouTube video showing crappy Chinese cheap electric motorcycles.  Apparently, they like to miss-label their battery packs and screw over their overseas customers.  So don't be surprised if the battery turns out to actually be a lead-acid AGM type instead of lithium.   

[Crissa]

Also, 'loss of power plus waiting equals working again' sounds like a standard thermal cut-off.

-Crissa