VEC 300 "Throttle Error" when any load behind 12v buck converter

[Evolknuj]

I have a VEC300 48v with a 52v battery pack driving a BLDC 5kW for my electric Morgan F4 themed cyclekart (you can probably find my earlier posts).  I frequently lose power and then get 14 beeps from the VEC300, indicating "throttle problem" a la https://goldenmotor.com/SMF/index.php?topic=6485.0 (I don't have the same behaviors/problem as that one, just the same 14-beep throttle code).  Mine seems to happen at different times -- sometimes at low throttle, sometimes while powering up a hill, sometimes almost as soon as I turn it on, sometimes its when I put it in reverse, etc.  If I turn the key (e-lock) off/on again, it's fine... till it happens again.  Sometimes it goes for a few minutes before it happens, sometimes it's practically immediate.

I already replaced the wiring from the GM foot throttle to the VEC300, no change.

The interesting part is that it seems to only have started once I added a 12v circuit to the car, driven from a cheapish 12v stepdown converter (search amazon for 'Golf Cart Voltage Reducer Converter 120W/10A 48V to 12V', it's essentially what I have if not the exact same seller).  The 12v system drives LED headlights and a set of amplified speakers.  Almost as soon as I added this circuit, the problem started happening.  I tried disconnecting the speakers first, but the problem still persisted.  Last weekend I completely disconnected the step down converter and the problem did not occur at all.

Now my sample size is very small, I only drove around for maybe 3 miles after disconnecting the 12v system, so more testing is obviously needed.  But if it continues to be a non-issue as long as the 12v system is not present, but is an issue when it is present, what could I do to solve it?  I could live without speakers, but I need 12v for headlights, brake lights, etc.  Is there a common kind of interference signal that could be introduced by a step down converter / buck converter that could be causing trouble for the VEC?  Or a common way of isolating the 12v system from the VEC.... whilst still drawing power from the 48v system (i.e. not a separate battery)?

It is possible that the problem isn't really gone of course and that I'll continue to hit it with more testing.  In which case my next suspicion would be that the throttle voltage is a little 'off' due to my battery being 52v rather than 48v, and occasionally the throttle signal is out of the expected range... any tips for testing that or how to adjust it (I have the USB cable)?  I'm not keen on trying to watch a multimeter for any spikes whilst driving down the road.

Thanks!

[Tommycat]

Hi Evolknuj,

If the problem does indeed follow the 12volt circuit addition. I would be curious if you are possibly using a common negative frame type grounding?
Or is ALL the wiring, positive and negative, run individually and separately? Tapping directly off the battery's output?

I don't think the difference in voltage input would be a factor. As the controller uses a final voltage regulator that should maintain a consistent 5 vdc output no matter which one is used.

Perhaps if you can lift the back wheel off the ground and safely secure your car when the issue is present to test the hall sensor throttle. May give some clue.

For more information on hall sensor throttles and testing you may want to look over this thread...

Guide to Hall Sensor Throttle operation, testing, and modification.

No foot throttles in there, but I think you'll get the jest of it.


Regards,
T.C.

[Bikemad]

Perhaps if you can lift the back wheel off the ground and safely secure your car when the issue is present to test the hall sensor throttle. May give some clue.

If you have the brake switch connected, you should be able to check the throttle voltage with the brake applied to see if the signal voltage goes above or below the maximum and minimum throttle voltage settings programmed into the controller.

Another option would be to temporarily unplug the hall sensors to allow the throttle signal voltage to be observed without the motor running.

Alan
 

[Evolknuj]

Thanks for the quick replies and suggestions!  It will take me a bit longer to get back to testing/investigation unfortunately :-)

Re Tommycat's question: all the wiring is individually run wires, either off the battery terminal or off a wire connected to the battery terminal (i.e. equivalent), NOT using the frame for anything electrical.

[Evolknuj]

Long time away, but I've found myself with more time on my hands recently  so I've resumed experimenting with my threewheer using the VEC300.  It's 99% reliable as long as there is no load on the 12v side of the buck converter.  But just about any draw on the 12v system can cause the controller to cut out and do it's 12 beep routine.  Yes, 12 beeps, aka throttle error code, not 14 from my original post.  I'm not sure if my original post was in error (miscount, mistype, look up other probems and assume it was the same).

Over the weekend I installed and hooked up LED brake lights.  Attached is a wiring diagram, it's pretty dang simple.  But even without driving at all, depressing the brake pedal switch will cause the VEC300 error about 95% of the time.  Literally just turn everything on, press the brake, and get 12 beep error code.  The brake lights are just a couple of LED bulbs -- I'd bet they're pulling less current than the speakers!

So on the plus side, I don't need to figure out how to get the rear wheel off the ground etc etc as Tommycat suggested, and the actual operation of the throttle pedal isn't involved at all.  It's definitely the 12v system somehow causing interference.

I've found a few search results that say that that buck converters are known to cause high frequency interference, e.g. https://www.eetimes.com/how-to-control-input-ripple-and-noise-in-buck-converters/#:

If it isn't filtered, DC/DC converter input ripple and noise can reach levels high enough to interfere with other devices powered from the same source

But while it says there are simple solutions, the rest of the article is definitely not clear to me.  I suspect that adding a capacitor somewhere might help, but I'm not sure if I'm right, where it should be added, how big it needs to be, etc.

The other thing I've noted is that the voltage across the 48v side of the buck converter drops from ~55v to ~53-54v per my multimeter when the brake pedal switch is closed.  So it could be either the voltage drop or some sort of noise that is impacting the VEC300.

Do these details suggest ideas or pointers to solutions?  I could carry a completely separate 12v battery for 'accessories' but that sure seems like the wrong approach.  I would think any EV would be using one of these buck converters for a 12v system, drawing from the main battery voltage.  It wouldn't surprise me if my buck converter was some cheap un-filtered model... but I can't tell how to identify a "good" one either -- they all look like they're using the same basic design.

Thanks!

[Bikemad]

Hi Paul,

My knowledge of electronics is somewhat limited, but I'd try placing a suitable diode and/or a resistor into the feed wire to the DC/DC converter to see if it reduces the high frequency signals travelling back up the wire to the controller. 

So on the plus side, I don't need to figure out how to get the rear wheel off the ground etc etc as Tommycat suggested, and the actual operation of the throttle pedal isn't involved at all.  It's definitely the 12v system somehow causing interference.

As the error code indicates that the "throttle input is abnormal", it would still be very useful to know for sure whether the voltage on the throttle signal wire actually changes when the brake is applied.
Checking the throttle signal voltage (especially while the brakes are applied and/or the speakers/LED lights are turned on) could be very important. 

The other thing I've noted is that the voltage across the 48v side of the buck converter drops from ~55v to ~53-54v per my multimeter when the brake pedal switch is closed.  So it could be either the voltage drop or some sort of noise that is impacting the VEC300.

A 1~2v drop on a 48V battery does seem to be a bit much for a couple of LEDs, are they high power LEDs?

Do you get the same voltage drop if you measure the voltage directly across the battery and the controller terminals?

What is the current rating of the double pole switch shown on your diagram?

Unfortunately, I don't know what else to suggest.

Alan
 

[Evolknuj]

The double pole switch is a battery disconnect switch rated for 180A continuous duty, so I'm pretty sure it's "good": https://www.amazon.com/gp/product/B012QNZFKI

I don't have a lot of details on the LEDs unfortunately, other than that they're 12v and LEDS.  They (like my headlights) are from this kit for motorcycles: https://www.amazon.com/INNOGLOW-Motorcycle-Headlight-Driving-Kawasaki/dp/B01MRUOU6H
They're satisfyingly bright (visible during the day) but nothing crazy.  The voltage drop did seem surprising however which is why I mentioned it before -- I don't know how much voltage drop is normal, but that does seem high.  It's higher than for the headlights or speakers, and much easier to trigger the 'problem' with the brake lights, though any of the loads can trigger it.

I measured the voltage drop where the (V) is in the diagram, but I'll see if I can measure a few more spots, including the throttle inputs.  I'll also see if I can affect anything by putting the tail lights in series rather than parallel or similar (there are two lights of course, not just one as in my diagram).

Any tips on how to try "suitable diode and/or a resistor"?  I have no idea what would be 'suitable' or how to determine whether to 'and/or'  .  Embarrassingly enough, my degree is in Physics but that was decades ago and I didn't get a job doing physics, so it's almost all gone.

[Bikemad]

180A continuous @ 12V is only 2160 Watts, which could be less power than you will be passing through it. 

I presume you have the link wire and the DC/DC converter on the smaller ignition terminals and the controller and battery cables on the larger ones:




For a resistance, try placing a 12V 60W halogen headlamp bulb in the 48V supply to the DC/DC converter and see what happens.
The bulb may get warm (or possibly quite hot) but should not blow unless the DC/DC converter is pulling more than 5 Amps/360 Watts from the battery.

If that doesn't stop the error, try adding a 10A 1000V rectifier diode or a diode with at least a 5A 60V rating.

Regarding the 1~2V voltage drop when the brakes are applied, I only see a voltage drop of 0.16V (160mV) on my 48V 10Ah LiFePO₄ battery when I switch on a very bright 9W 12~80V LED lamp.

Try temporarily disconnecting the LED brake lights and see if the voltage drop still occurs when the brake switch is activated. I'm wondering whether the controller is somehow using more power when the regen braking is activated. 

Are you using the same brake light switch for both the brake lights and the controller's brake function? If so, is it wired using the single Yellow and White +12V "high Level" brake wire on the controller?



It will be interesting to see if this unusual problem can be cured relatively easily.

Alan
 

[Evolknuj]

Thanks for the pointers Bikemad!  Responding in order (I think):

The double pole switch is on the 48v side, so it's 180A at 48v rather than 12v.  I'm not sure exactly how accurate my analog ammeter is (I picked it mainly for aesthetics) but I generally try to stay below 80A (3840w).  Room to spare there (battery BMS claims to limit to 90A continuous).

Yes, the larger terminals go from the battery to the controller, and the smaller terminals go from the battery to the DC/DC converter.

I don't have a 12V 60W halogen headlamp bulb laying around.... but I'll see what I can do.

Can you explain more about the rectifier diode?  I.e. where in the circuit it should be placed and what it should be doing?  I remember from school that a diode only allows current flow in one direction (and if it's a light emitting diode it will emit light as well, as long as the current flow passes a certain point)...  but what would it be doing in this case and what guides the volt/amp choice?

Disconnecting the brake lights and pressing the brake switch would do nothing -- without the lights there'd be no circuit through the switch :-).  To clarify, I'm not using the regen brake feature / brake connection on the controller at all -- the 'brake switch' I have is just a momentary switch on my brake pedal such that when I press the pedal it allows the brake lights to turn on.  The actual braking is by a hydraulic piston to a disk brake.



Overall I do agree that the voltage drop when pressing the brake switch is surprisingly large.  The drop when turning on the headlights or turning on the speaker amplifier is much smaller.  I also want to do some more measurements though -- e.g. measuring voltage at the controller itself.  I'm currently measuring at the 48v side of the DC-DC converter itself, where the wires are much smaller etc.
Given that even small loads on the 12v side seem to trigger the problem sometimes, I'm considering just punting and getting a separate 12v lipo battery so the DC-DC converter is eliminated and the systems are completely separate.  It'll be a minor pain to deal with two batteries but that's inconsequential compared to reliability on the road.  And then I'll have another battery for other projects too, like a wearable smoke machine...  and usb ports for charging my phone while driving...   But I'll be trying for more diagnosis first.

[Bikemad]

Can you explain more about the rectifier diode?  I.e. where in the circuit it should be placed and what it should be doing?  I remember from school that a diode only allows current flow in one direction (and if it's a light emitting diode it will emit light as well, as long as the current flow passes a certain point)...  but what would it be doing in this case and what guides the volt/amp choice?

The diode is placed in the feed wire going to the DC/DC converter as shown here:



The diode is there to (hopefully) prevent any unwanted high frequency, higher than battery voltage pulses (produced by the DC/DC converter) from travelling back up the supply wire to the Battery/Controller and subsequently causing interference with the controller's electronics.

the voltage rating of the diode need to be higher than the maximum battery voltage that would be passed through it, and the current rating needs to be higher than the maximum current passing through it to power the DC/DC converter.

If the DC/DC converter can supply a maximum current of 10A @ 12V  (120 Watts) this would require a current draw on the battery voltage supply wire of 2.7A @ 48V if working at 93% efficiency.

The reason I recommended the 10A 1000V rectifier diode was because the voltage and current rating are both higher than you require and it is readily available and cheap to buy. 

As you are not using the braking feature of the controller, this also means that you have bypassed the safety power cut off feature that is typically activated when braking. This feature is particularly useful if your throttle jams and the motor is stuck at full power.

Alan
 

[Evolknuj]

Good to know about the 'safety power cut off feature' -- I have both the battery disconnect (the big double-pole switch) and the elock right next to my hand so would have to rely on those (or yanking out the lead from the battery, right next to the other hand) if the throttle got stuck.  I avoided the Brake and High Brake wires because I never found clear documentation on their behavior, e.g. whether connecting the wires would immediately cause MAX REGEN!!!!!! or if its supposed to have a throttle-pedal-like behavior somehow despite having only two wires for Brake and just one for High Brake....  and even if it did work, wasn't sure how it was supposed to return charge to the battery without doing bad things to other things on my electrical diagram.  E.g. the dc/dc converter may not like having the controller trying to push current back into the battery.  Heck, the battery may not like it either -- it charges through a separate connector, not the main output terminals.  So I felt it was simpler to skip regen braking.

If the Brake connection to the controller doesnt trigger regen, only tells the controller to cut the throttle... then I could replace the brake switch I have with a two pole switch and have one pole turn on the brake lights and one pole connect the Brake line to the controller so one couldn't accidentally (or due to fault) apply brake and throttle at the same time.  Maybe?  Where can I find more info about how the Brake and High Brake connections should be used?

[Bikemad]

Unfortunately, the regen/EBS is not variable during operation, but the level of regen current and maximum regen voltage can be set using the programming software, and I would expect the level of regen braking force to be affected by the regen current setting.

The three brake wires allow for two different methods of triggering the regen function. The most common method is via a simple momentary switch connected to the brake lever or pedal which simply connects the Blue&White brake (+5V) wire to the Black (GND) brake wire when the brakes are applied.

The alternative method involves connecting the +12V Yellow&White high brake wire to the switched side of a conventional 12V brake light switch used on 12V cars and motorcycles. The regen is then activated each time the controller receives a 12V feed when the brakes are applied.

Unfortunately, I don't have a VEC controller/motor setup to test so I don't know if the throttle override still works if the regen is disabled. 

Alan
 

[Evolknuj]

Tried the diode, no improvement unfortunately.  Tried a separate 12v battery, worked perfectly (of course).  I don't quite understand how to use the high brake connection as there is no common ground currently.... But I'll think about it more 😁.  I think my buck converter experiment was a failure unfortunately, which is wierd.  Could be a cheap flawed converter, but I have everything working now w a separate battery so I may just let it go.

[Bikemad]

I don't quite understand how to use the high brake connection as there is no common ground currently.... 

You would have to complete the circuit by adding an additional ground wire between the 12V battery negative and the 48V battery negative to enable the switched 12V brake light feed to flow through the +12V high brake wire.

Alan
 

[Evolknuj]

Necroing my own thread to post an update, in case anyone is in a similar state.

Even with the separate 12v system, I occasionally would have the controller cut out (usually while going up a hill, mighty inconvenient as I don't have a parking brake).  I finally got ahold of a windows machine to program the controller.  Disabled the throttle voltage protection, bumped the temp warning levels up by 10 degrees, reduced the maximum battery draw from 110A to 100A, disabled the regenerative brake feature entirely (not hooked up at all in my case) and told it to clear low-voltage on throttle-off.  Working fine so far, over about 10 miles of hills.  My best guess is that my battery (which is theoretically rated for 90A) drops voltage when it's over-current protection kicks in.  Which either messes with the throttle protection as the voltage changes, or kicks in the controller's undervoltage protection.  So while i'm not sure which setting seems to have 'fixed' things, I'm guessing it's the throttle protection and max battery draw settings.

Fingers crossed that it stays fixed, and then at some point I'll try hooking up the 12v buck converter again so I only need the single battery.