Victron damage if BMS disconnects battery?

Hi!
Victron MPPTs need to be powered by the battery - by that, I mean you are meant to turn on the battery, after which you can turn on the solar PVs in the system. When you turn off the system you do it the other way around, turn off PV power and then battery power.

Having the MPPTs powered by PVs alone may damage them.

So, there's a scenario when the BMS would disconnect the battery... That means the MPPTs would be damaged by the PV power coming in...

Any ways to avoid this?

I believe proper BMS and MPPT settings would do, but just throwing this out at the community to see what you think.


Thank you.

tonyg said:

Hi!
Victron MPPTs need to be powered by the battery - by that, I mean you are meant to turn on the battery, after which you can turn on the solar PVs in the system. When you turn off the system you do it the other way around, turn off PV power and then battery power.

Click to expand...

Nope. Victron MPPT need to be connected to the battery FIRST, ONCE in order to establish the battery voltage.

If you disconnect the battery, the MPPT will continue to operate on PV provided there is sufficient solar. If it's load port equipped, it will continue to power those DC loads as well.

It's somewhere in the documentation, and I've personally witnessed this when I deliberately disconnected my battery, but my system stayed powered, including the Quattro because I had more than sufficent solar to do so.

tonyg said:

Having the MPPTs powered by PVs alone may damage them.

Click to expand...

Nope. Only true for cheap crap and PWM. Lots of discussion about this over the last two years and this type of failure is exceedingly rare especially with the hardware typically used by forum members.

No need to comment on the remainder.

EDIT: Check Q4

Mega like to your above post!
Thank you for taking your time to explain, very glad to hear this.

Bravo Victron as well!

The other scenario that comes up is the BMS disconnects due to an over-voltage situation. Charge is certainly stopped. But the discharge is still available so the MPPT can draw upon the battery just fine. Not all BMS will work like this, but the good ones do.