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solarchain avatar image
solarchain asked

Wiring for VE.direct non-inverting remote on-off cable

I have two MPPT controllers, that I need to turn off during high voltage event, (HVD) using an external BMS. I have a BMS working that turns off charging to my multiplus 3000 using the 2-wire BMS assistant and the auxilary ports. Thinking I can use the HVD BMS shutoff wire which connects to the multiplus aux and splice them into my two MPPT controllers using two VE.direct non-inverting remote cables.

Is this possible? and if so, would anyone have a drawing the shows how i would make these wiring connections? The VE.direct cables use a sing yellow wire only, not a two wire pos and neg that the Multi aux ports use.

I have not consider using a BP100 due to the two way current limitation/fire potential.

Thanks in advance




MPPT ControllersVE.Directwiring
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nebulight avatar image nebulight commented ·

We need a little more information about your BMS. Is it just an optocoupler on the BMS side or is it actually sending a battery voltage? Can you measure the voltage of your HVD wires from your BMS? If it's battery voltage, then you can wire to the high for the non-inverting remote on-off, but I would suggest isolating the AUX ports from your battery voltage with an optocoupler or relay.

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solarchain avatar image solarchain nebulight commented ·

From the manufacturer .. "there as is just a transistor fully isolated so you can only see open or close circuit and will not get anything on continuity as there is a BJT transistor so even with close circuit you have about 0.6 to 0.7V drop across when close circuit and open circuit is open so no voltage drop. With a multimeter you can only test with diode test that will show open circuit if open and 0.7V or so when close circuit."

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1 Answer
nebulight avatar image
nebulight answered ·

Per the specs of the inverting cable:

  • Maximum input voltage: 70V
  • Minimum input voltage needed for switch on: approximately 6V
  • Switch off level: input voltage must be less than 1V or must be free floating

In order to use this cable, you're going to have to add an additional switch (maybe something like this) to your HVD output. Use the FET to control current going to the on/off cable. However you need to get the specs of the transistor to make sure it will work.. This is more of a question for your company that makes your BMS. I'd check with them.

And if you are using the BP100 for just the MPPT, current will only flow in one direction with the output of the MPPT so you should be able to use that without any issues (I have a BP100 on the output of my 100/50 MPPT because I have the ve.direct port going to a GX).

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