Trouble with MQCON inverter, won't give any power, won't connect to computer

[m34tbag]

Hello all,

I'm having some trouble connecting to my MQCON 72250 inverter.

I'm rebuilding a bike at the moment (Suzuki GS500 conversion) but im having some technical troubles with it. Currently I can't get the throttle to work and I can't connect to the inverter to do any trouble shooting. First of all, to be clear, the bike did work. My friend rode it, then brought it down to his house where it sat for a few months, then I've pulled it apart.

When I turn the bike on, everything powers up, including the dash display showing 150kms (range display maybe?) Then after a minute, that changes to zero. If I twist the throttle, i get a tiny little bit of power and then it cuts out completely, including the display going to zero. If I give the bike a rolling push, then twist the throttle, it shudders and cuts out.
After a minute, it resets and I can twist the throttle but it does the same thing and cuts out, but sometimes it'll surge backwards a little bit before doing that. Usually it goes forwards.

My initial thought is that its a throttle fault. Everything seems like its wired up correctly, 0.8v throttle closed, 4.3v throttle open.

Maybe its a hall sensor fault with the shuddering?

Unfortunately, I can't connect to the inverter. I've downloaded what I think is the right program from the manufacturers site, then connected from my laptop to the inverter with a usb cable. I can't see anything connected in the computer device manager and the program can't detect the inverter. The laptop is running windows 7.

I've also got a hc-06 Bluetooth module and tried plugging that into the usb, then trying to connect with the app on my phone, but no luck. My (samsung) phone can see and pair with the bluetooth module, but the app doesn't detect anything at all.

I'm not sure what else to try, or why its now doing this when it did work previously. I haven't changed anything electrical yet as I wanted to confirm all the components working together before I began changing parts and rewiring.

Any suggestions I could try? Im not hugely knowledgeable about all of this, but im willing to try things and to learn as I go.

 

[dominik h]

The Sabvoton/MQCon have a special USB cable , an ordinary won't do the job. Do you have the USB Bluetooth adapter? You can see nearly everything with the phone app.

Have you measured the battery voltage.
To my it sounds like the BMS is cutting off.

 

[E-HP]

Sounds like your battery is the problem. Were you able to fully charge it?

 

[m34tbag]

The battery is fully charged, currently sitting at 88.5v 85.8v

Of course they have a special usb cable ffs. Do you know what's so special about it? other than it being a male to male cable?
I don't have their specific usb dongle either, but from my research i've seen others mention that its a HC-06 bluetooth module, I had one of those in my box of electronics/arduino stuff, so I dug it out, soldered on a usb cable to the pins and plugged it in. I've got the app on my phone, but it won't see the bluetooth dongle so it won't display anything useful.

one of my issues atm is I'm about to go on a trip for a few months very soon, so I can't really risk ordering things from China if they are going to take a long time to turn up. It'd have to wait until I get back in July.

 

[eee291]

i've seen others mention that its a HC-06 bluetooth module

Might need to change baud rate like for the Kelly controllers.

 

[E-HP]

The battery is fully charged, currently sitting at 88.5v

What type of battery is it? Lithium ion, LiFePO4 ?

 

[m34tbag]

as far as I know, its a Li-Ion 18650 cell pack, 20S19P configuration, built in bms

 

[E-HP]

as far as I know, its a Li-Ion 18650 cell pack, 20S19P configuration, built in bms

20S would be 84V fully charged. Maybe you're above a high voltage cutoff setting for your controller.

 

[m34tbag]

sorry, typo, should have been 85.8v. That's what my multimeter displayed.

But, still, thats indicating that the cells are fully charged to 4.22v, which is still too high for an 18650 cell. I'll have to investigate that as well.
Personally, I don't like to take 18650's over 4.1v

Thats a good point about a high voltage cutoff. I'll try deplete the battery a bit and see if I get a change, This could be something.
Still leaves me with the issue of trying to connect to the inverter, But i've got the baud rate of the bluetooth controller to look into as well as ordering a cable.

 

[amberwolf]

Verify your meter's battery is good, too, because a low battery will give a higher voltage reading than it should, and can account for what looks like an overcharge.

Also, does the voltage change when you place a load on it? (meaning, as you engage the throttle, etc) If there is enough voltage sag it could trigger LVC in the controller. (espeically if something happened and the LVC setting was changed in the controller, either by accident or by a failure within the controller).

If it were the battery cutting out due to cell-level voltage sag, the entire system would power off--if the dash and everything else doesn't turn off when it cuts out then it's not the BMS cutting power for whatever reason, it's in the controller itself.


Incorrect motor direction, even occasionally, may mean a problem with the controlelr sensing motor position, and that usually means a problem reading the hall sensors. That can be a poor connection (contact issue at connector, crimp or solder problem inside motor or controller or connectors, wire problem anywhere from inside the motor to inside the controller) between controller and motor, even just intermittently. Or it can be an electrical noise problem from current induced from phase wires into hall wires--this kind of problem happens more when there is a high load on the motor, like at starts from a stop or other high-phase-current situations.

 

[dominik h]

In the MQCOn USB-Cable is some sort of USB to seriell device integrated, but don´t ask me for details, as i do not know them.