Is it valid to test to test the LifePo4 battery with a multimeter? I’m unsure if it has an internal mechanism to switch off its output. The BMS isn’t turning on and the measured voltage is 2.3V. Are these batteries dead? The manual says they’re not supposed to go below 3V.
The bms has likely switched off its output. Yes they can switch off mosfets and that makes it seem like the cells inside are dead, when it is really just disconnected.
Maybe can be recovered (bms woken up again) by using a 12v victron battery charger if it is 12v.
The battery should have a recovery method in its manual
What type of battery is this.
The 200Ah version.
Make and type are required to give a proper answer. As you are asking here on the Victron site I assume it is Victron, if so is it the Smart Lithium the Smart NG Lithium or the Superpack battery.
BAT512120610 is the part number
OK, there is no BMS in these, the output terminals are directly connected to the cells. At a total battery voltage of 2.3V it will have suffered permanent damage, possibly dangerous levels of damage. The manual (Section 6.1.5) has a recovery procedure, but this should only be attempted under supervised conditions and very very cautiously if you are aware of the risks and have suitable equipment.
And there’s nothing special about measuring the voltage on these other than measuring across the two exposed terminals?
Not that I am aware of. They can be opened with some difficulty and each cell measured. See linked file on swapping out the circuit boards to see inside the batteries and how to get in. Again, extreme caution and appropriate safety measures required to do this.