I write this post in order to show up in searches anywhere of any one who is trying to build an ESS energy storage system with victron multiplus-II and tesla battery modules. I drop as many keywords as I can, for googles sake. Be warned.
For all others who wonder whats wrong with their system. You are NOT alone, and you should have been told in the specs!
My setup: I have 3 Multiplus-II in 3-Phase mode and 4 Tesla Modules (2 parallell, 12s) with SimpBMS. Victron SmartShunt as secondary battery monitor. Uptodate as of today with newest ESS Assistant and Firmware for the Multiplus. CerboGX is the brain. Newest test finished 1h ago, after the update. No change.
Here are the very bad news:
Multiplus-II does not discharge bellow 40.6 Volts in ESS mode. The 38V lower limit from the specs does not apply!
I'm referring to those posts:
and many more
Is there an official (non-forum) statement of Victron about this?
Why isn't it in the specs? Why isn't it in the manual? Did I miss it?
The only thing we have is one answer here:
Where a Victron tech clearly states, that this is the discharge limit of the Multiplus in ESS mode.
NOT 38Volt (DC IN as in the specs!)
BEWARE! THIS MAKES THE MULTIPLUS-II the WRONG CHOICE FOR ESS WITH TESLA MODULES
AND THIS LIMITATION SHOULD HAVE BEEN MADE CLEAR IN THE SPEC SHEET!
I feel disappointed and I'm really sad about not being able to use the battery I have to the capacity it could.
I reject the notion, that discharging 12s Li-Ion Cells bellow this limit would only yield marginal capacity. I have a 20kwh battery pack and I can only get barely 12-13kwh out of it BECAUSE of this limit. This is NOT marginal, even though I'm only charging to 4.1(perCell), there are at least 15kwh to be expected.
To get this once and for all settled for all of us I provide now full documentation of my settings to rule out any configuration problems for others.
Lets start with the beauty- problem:
There is NO choice for Li-Ion (min 3V - max 4.2V)
This I have tried higher and lower, to no effect
Dynamic Cut-Off I have tried upside down and the way it is now, which is probably reversed (but it doesn't have any effect either way..
I am sure, the BMS is NOT limiting current. This is taken from the BMS window at 40.6 Volts when discharge was stopped. DCL usually fluctuates, as it is set by SimpBMS. It has not yet been limited to 0.