BYD B-Plus L 2.5 / MPPT 250-60

Q&A and troubleshooting
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1

I’m trying to gain a deeper understanding of how BYD and Victron systems work. The setup consists of the following components:

  • 3 x BYD B-Plus L 2.5 batteries
  • 1 x BYD BMU
  • MPPT 250/60 MC4 Ve.Can
  • Quattro 3000VA
  • Color Control GX (CCGX)

Question 1: Apart from the BMU instructing the batteries on their operations, does the BMU receive its reference voltage from the CCGX? In other words, does the CCGX directly tell the batteries what to do?

Question 2: When the VE.Direct is connected between the MPPT and the CCGX, the MPPT stays in absorption mode at 56.5V. However, when measuring the voltage at the battery modules with a multimeter, it reads 51V. When the VE.Direct is disconnected, the MPPT begins charging the batteries, and the voltage measured at the MPPT is almost identical to the battery voltage (51.8V at the MPPT and 51.3V at the batteries).

If anyone has any insights into what might be wrong with the system, it would be greatly appreciated.

2

I answered my own question :grinning:
If anybody ever experienced the above, the likely cause is improper termination at the DC breaker.

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3

The breaker is also a bit small for the application.

4

The beauty of others’ installation. (We were called there to fault find)
Anyways, the cable (25mm2) was only 0.3m long before terminated into the mppt. We replaced the breaker and downsized the cable to 16mm2.

Had to reboot the color control gx too because the mppt did not show on device.
All back to normal operation.

5

Settings - general - reboot.

I only mention the breaker as being undersized. As it is in amperage and arc quenching ability. Lithium battery arcs will cause that breaker to burn.

You say it was between the mppt and battery? It is also undersized for that 70A output will burn a 63A dc breaker.

6

Yes. Oops not a 70 actually it’s a 250/60