Cycle analyst shuts down momentarily (suspect the THUNE)

Hi, I have a new ebike setup and a problem has occurred. After about 10 kilometres (7 miles) the cycle analyst shut down. The Vshutdown for the THUNE is set to 10 V (default). This is my bike setup: DD Crystalyte HS3540, GRINTECH sensorless 40A 72volt controller, CA-DPS (with external speedometer sensor), battery: Li-ion 20S8P. At the start of the ride the bike run like a dream with regen breaks working. But when the voltage sag go down to around 70-ish volt, the battery indicator shows empty and the CA screen goes blank, and I suspect that the THUNE goes below 10 volts. Fully charged the battery is at 84volt, but the BMS is set much lower than 70volt, I believe 60 or 64volt (so I "know" it is not the BMS that shut down the battery). When I turn off the key-switch and turn it back on again, the battery indicator shows almost full battery again and the CA-DPS (ver.2.4) start up again. This issue start to happen after I've just used about 1,5 Ah from the battery. The triangle-battery can push out 40A, but I have set it to 38A just for precautions.

Perhaps there are some adjustments to the CA-DPS I can do ? Perhaps maybe trick it by changing the battery-chemistry that can handle more sag, or by changing the sensing voltage/ratio so that the analyst "believe" the voltage is higher than it really is ? I could really need some help with this issue because the bike is brand new and is for sale.




--Why can't they make triangle LiFePO4 pouch cells ? Pouch cells are superior to 18650 cells--

endonuclease said:

The Vshutdown for the THUNE is set to 10 V (default).

Click to expand...

What does the THUNE do? is it a BMS?

If instead you mean a THUN BB torque sensor, it does not have any shutdown voltage, and cannot directly affect the system.

However, I can say from experience that if you are running that high a voltage, and using a THUN BB sensor on the CA, then you have to use an external 10V source to power the THUN, because the CA cannot handle the load on the 10V line with the high voltage battery you have. See the Cycle Analyst page on the Grin Tech site for details on this, or the V3 CA beta thread.

But when the voltage sag go down to around 70-ish volt, the battery indicator shows empty and the CA screen goes blank, and I suspect that the THUNE goes below 10 volts.

Click to expand...

What is the CA's shutdown voltage set to?

Fully charged the battery is at 84volt, but the BMS is set much lower than 70volt, I believe 60 or 64volt (so I "know" it is not the BMS that shut down the battery).

Click to expand...

Did you measure the voltage at the battery output (at the moment shutdown happens)? (since the CA screen actually goes blank then that does mean the BMS has shut off it's output).

If you haven't, you should do that, because if there are unbalanced cells in the pack, then as it gets closer to empty, these cells will be drained low enough to cause the BMS to shutdown all output to protect you from damaging them or causing a fire, by overdischarging them.

This is almost certainly what is causing the problem you are seeing.

Probably not the same issue, but I had a CA where one of wires inside the factory cable that goes from the CA to the motor controller had a slight break. So I would get all sorts of crazy intermittent failure where the CA would shutdown (go blank) and then maybe startup again a bit later. Of course it got progressively worse until it failed 100% of the time.

I originally thought it was one of the cables I made or connectorized and was intermittently shorting. But I discovered the broken wire when trying to debug the whole thing.

I did some adjustments in the CA-DPS "advanced setup", and Now; instead of it shutting down after 2 kilometres, it ran for 11 kilometres after the adjustments. I read in the manual that the pre-configured settings are for a bike between 300-600watts. So by turning down many configurations, I extended the "range" by almost 6 times. But the battery voltage went down from 84 volt to 79,3 after 11 kilometres, so it seems the battery is no the issue. I'll hook it up to my PC today and see what else I can do. If not I will get the CA-DPS power by soldering a cable to the divider pad, and in that way it will always receive 12V. My battery BMS is set to 40 amps, and i suspect that the Crystalyte motor takes it all and leave no amps to the CA-DPS. I adjusted the Amax to 37 when things went better.

If you really want people to help, you should try answering the questions they have, so they can have enough information to be able to continue to help. If you're just posting up your own testing and don't want help, you should say that.