Ensuring automatic black-start for a MultiPlus connected to a powered-down CCGX

There is a specific operating characteristic of the Victron Energy MultiPlus and Quattro inverter/charger products that makes things harder in a 'black start' scenario.

Given these starting conditions:

• The MultiPlus is supplied with AC power;
• There is an attached CCGX, but:
• The CCGX is not (yet) being supplied with power (the power source for the CCGX is not yet energised)

...Then the MultiPlus will not boot until either:

• The CCGX is powered up; or
• The VE.Bus cable between the MultiPlus and the CCGX is temporarily unplugged (it can be plugged back in immediately the boot process of the MultiPlus completes)

 

The Problem

If there is an attached VE.Bus master/controller (CCGX or indeed even just a USB-MK2 adaptor box), but that VE.Bus master box is powered down, the MultiPlus will not commence booting in the presence of AC or DC power until the VE.Bus master is powered up or temporarily unplugged.

The challenge with this behaviour is that it commonly creates a significant 'Catch-22' in black-start situations.

This can happen when the CCGX is powered from the output side of the MultiPlus (so that its operation is battery-backed and supported even when an incoming AC power source is absent), or when it is powered on the DC bus but the DC bus happens to be de-energised (after a total system discharge event).

The Solution

It turns out that there is an easy resolution to this situation.

Simply create an RJ45 patch cable to the CCGX from the MultiPlus that has pin number in the cable 7 cut.

That's all you need to do!

VE.Bus Pin 7 is the path by which the startup-inhibit behaviour in the MultiPlus is controlled.

Cutting that one wire (leaving the other wires in the cable intact!) results in the MultiPlus/Quattro system booting when any power source is supplied, even if the CCGX is not (yet) powered. This resolves what can otherwise be a deadlock preventing automatic black-start after a full system discharge event. 

How to make this cable

Here is one way to make that special patch lead:

• Take a standard RJ45 ethernet patch lead
• Carefully strip the outside insulation sheath back, part way along the cable, to expose the underlying twisted pairs
• Identify and cut the #7 wire (brown/white according to standard RJ45 ethernet cable colour coding)
• Separate and insulate the cut ends with insulation tape, and then wrap the whole location up with more insulating tape
• Mark the cable to indicate that is has pin 7 disconnected (to avoid confusing someone in the future who might use the cable somewhere else!)

You can also do this with an RJ45 cable joiner unit. Crack the joiner open, cut the correct wire, and close it up again, to create a ‘magic’ joiner. Again, be sure to mark the joiner clearly to avoid making somebody else's life complicated if they try to re-use it in some other role later on!