Sabvoton 72150 Suddenly Cuts Out

[LipoRider]

Anyone experienced a problem with their Sabvoton ESC suddenly cutting completely out while riding? Especially during acceleration.

Back in 2017, I put together a custom fast enduro e-bike with a Sabvoton SVMC72150(M). But now the Sabvoton has developed a serious flaw. I've ridden this bike over 5000 miles since enjoying easy smooth powerful 10,000W acceleration off the line for years.

Whenever I apply hard acceleration to at or near full throttle from slow speed, the Sabvoton suddenly cuts out with a slight "clunk" sound that shudders the bike a bit. The Sabvoton's LCD goes for a few more seconds then goes to black. I have to press and hold power for about 5 seconds before it comes back again but it will then shut down to black screen. I have to do this once or twice more before the Sabvoton is back to normal operation to continue riding.

Now imagine this cut-off happening when I'm at the head of a line of cars! Already happened a couple of times but luckily I was in a position to get to the side of the road or pull into a parking lot. Now I'm very nervous riding my e-bike. If I have to use it, I take the small roads and be very gentle with the throttle.

This bike was awesome because it was combined with a powerful LIPO battery that never even sweated giving 10,000W boost for a few seconds when I power away from the cars after filtering up to the head of the line. No way I'm doing that anymore with this Sabvoton's shutdown problem.

This is not any limitation with the Sabvoton's settings either I don't think. I've set the cutoffs to high levels. It seems to be a hard crash in the Sabvoton's firmware or something shocks its control logic that causes it to shutdown and reboot. If it were amp limitations, the Sabvoton would just limit further acceleration and not crash out like it is now.

I have checked my motor's hall sensors with a volt meter and confirmed all three sensor sires are operating normally. Its not a hall sensor issue because everything is completely smooth when its operating. If it were a hall sensor problem, I'd be getting stuttering especially at startup but its always buttery smooth as its ever been.

I have played around with disable/enabling field weakening settings and regen braking on/off with no luck.

Anyone have Sabvoton issues like this? I've emailed mqcontroller@hotmail.com earlier this month but have not received any reply. Its an older unit and could benefit from a firmware upgrade but I've never seen such files available and I'd be concerned about how well its firmware update works and risk bricking it completely.

EBike Details:
MQCon Sabvoton SVMC72150(M) 72v 150A speed controller
28Ah 17s LIPO
17" motorcycle rims

 

[E-HP]

Can you check the battery voltage at the output terminals right after it happens? The display staying on then turning off slowly seems a lot like if I switch off my battery, and the display stays active until the caps discharge. Doesn't explain how you are able to get the display to almost fire up again, unless there's still some charge left in the caps. Are you using a fuse or breaker? I'm assuming no BMS since you're running Lipos.

 

[amberwolf]

Complete loss of power where the display actually turns off is usually a battery issue, but normally only if there is a BMS in the battery.

The other type of problem that could cause it is a poor connection, if it's dropping in voltage under heavier loads because of high resistance.

The same type of problem can be caused by cells in the battery sagging in voltage because of a problem in the cells (or interconnects between them).

 

[Dui ni shuo de dui]

I would check the battery for voltage sag and also the ignition/keyswitch wire for a bad connection or a short.
A few years ago I had a similar issue with a sabvoton controller, it turned out to be something wrong in the wiring harness. I never actually found the cause: I built a completely new wiring harness and from that point the issue was gone.

 

[DogDipstick]

ARFE you absolutely sure the throttle MAX value is not in the ohm region when fully turned?

I found this to be a problem with some high end and low end 0-5K pot throttles. IF you hit it hard, throttle is little worn out the WIPER leg goes to high to fast...

In the throttle connection...
Use a multimeter between the +5v ( red) throttle line ( backprobed and powered) .. to ground... See the " at rest voltage".... should be low 1-2v.. and when you turn the throttle it gets higher... to 4-5v...

SO unpowered, take a reading on the throttle ( disconnected) from WIPER to RED5v+.. and at ZERO throttle, you should have 5000 ohms ( 5K ohms) on the meter.. and as you turn the throttle this will go down to ~800-1000 ohms... MAX.

IF your throttle turns to far, this becomes 800-700, 600, 400, 200... 80, 60, 20, 10 ohms.... and NOW the throttle is a direct short on the WIPER line to ground... ( no resistance... ) and has turned to far and the SAB see this as a throttle fault (* short to ground through the red to black given the wiper gives no resistance to measure... ) and the jolt happens. Throttles have internal mechanical at rest stops ( plastic tabs that keep the throttle from turning the potential wiper to far) that are supposed to keep the range of resistance from 5K -1Kish... and these can bend, or shear off, from crashes, and now the throttle will provide way to little resistance to make the 0-5v throttle line look like a short.... and cause a reset and a jolt.

This is what my Sab did until I fixed the throttle and not let it get under 1K ohms on the full application... for the SAB would see it as a fault, throw a red light blinky and shut down.

My Magura throttle was giving a value of 4600 ohms at rest, to 18 ohms when fully applied and the voltage sensing circuit in the controller would see full throttle as a dead short and go into protect. Display would go black,, Bike would jolt to a stop.

I changed the potential meter adjustment, inside the throttle, to actuate 5200 ohms to 1000 ohms, never going to low resistance on the high TH end and now it works fine. The internal stop was damaged. Bent from a old crash, I suppose, inside the throttle, and allowing the throttle grip to turn to much, letting the potential meter to turn to far ( to low R) creating a fault.

Try to measure the throttle you have, for fault, see if it is in the usable region, or try a different throttle for a test.

My bike I'm talking bout is a Super 73 with a 72150(M). 25ah 1800wh lipo pack with a 200A contin BMS. Unloaded RPM is 1100rpm on a 20" rim ( 16" Moto rim) for 65mph unloaDED .... NO FOC.

 

[E-HP]

The other type of problem that could cause it is a poor connection, if it's dropping in voltage under heavier loads because of high resistance.

Reminds me of when one of the connectors on my truck's battery is loose or corroded, and not making good contact. The dashboard lights up, the radio turns on, but once you turn the ignition switch, everything goes dead. Wait a while, and the radio and dashboard will light up, since the poor connection still supports that level of current, but not the starter.