Fresh build from Slovenia

Build, Repair & Mod
25

@kian - great job.

@lukomo - this is a problem I have been trying to solve as well.

The issue;

  1. You want to be able to connect and disconnect the batteries reliably.
  2. You want to be able to disconnect the batteries under load - for safety, in case your VESC or your remote fails dangerously - in the full throttle state.
  3. You want to be able to connect your batteries without the inrush sparking that eventually reodes your switch contacts.
  4. You may also want a lanyard to a safety switch to kill power if you fall off.

@kian’s solution looks good. I would love to learn more.

I have tried to solve this with the Maytech anti-spark switch, but the cannot handle the current. See this post, I have had three fail;

Maytech will not even talk to me now. I think the main issue is that Mossfet circuits simply cannot handle the big back EMF and high voltage spike that occurs when the magnetic field in the motor collapses when power is cut.

I am also looking at the Arduino option where the Arduino would also throttle down the motor briefly before disconnecting power. So the functionality would be;

  1. Arduino controls a 300A DC contactor (or Mossfet).
  2. Arduino receives the input signal from the remote.
  3. Arduino receives input from a waterproof on/off switch
  4. Arduino receives input from kill switch
  5. Maybe arduino talks to a BMS as well
  6. Arduino monitors temperatures.

Functionality;

  1. As @Kian highlights - when switch is turned on, arduino switches a relay with a resisitor in it to slowly raise the voltage to the VESC.
  2. When voltage euqalises, Arduino drops in main battery contactor.
  3. If on/off swithc or kill switch goes open, arduino throttles down motor for 2 seconds and then drops out main bayyery to propulsion system.
  4. If arduino detects loss of comms with remote, it throttles down motor and disconnets power.

There may also be the option to use the arm/disarm function of some VESCs.

I plan to use this arduino based processor which is safety rated and runs three cores in parallel to increase safety;

https://hitex.co.uk/about-us/topics/aurix-preferred-design-house/shieldbuddy-tc275/

I have used them previously and they are very fast.

I will use one core to control relays. One core to control comms and one core to monitor the other two cores.

I would love to know everyone’s thoughts.

I am just starting a new build. It will have twin MHZ 58s with scorpion motors(on their way) and will use 2 x MakerX new 300A VESCs.

The other reason I am running the remote through the Shiledbuddy is that I need to control two VESCs from the one remote. Essetially, I will have two batteries, two VEScs, two motors and two jets, so there is no single point of failure other than the remote and the Shield buddy (which is safety rated).

I will also have a waterproof hall effect single axis throttle lever built into teh board so that you can over ride the remote.

1 Like