We build boats from new, equipped with Victron Smart lithium batteries, Victron VE. bus BMS V2, Victron Smart Battery Protect 12/24-220 and a smaller Victron Smart Battery Protect for memory/constant plus.
hardwired from BMS (ATD) to H input on Battery Protect.
charging current from multiplus or charger/solar cells/engine gen, does not run backwards through the Battery Protect. the current only runs one way in this.
after 12 months + from delivery we sometimes experience that Battery Protect no longer disconnects completely.
we can measure about 9.5-10.5VDC on the output side and it runs a small current enough to make LED light sources light up with weak light., nothing else works as intended. removing the plug on terminal H has no effect.
it’s not all boats we experience this on but there have been quite a few recently/too many anyway
Anyone else experiencing the same thing? solution or reason is very welcome
it is also a bit worrying, as BMS (ATD) signal did not result in total cutoff
Unfortunately this is not the case. I am aware of this limitation, with power flow backwards.
The principle in the installation is like the right example. instead the multiplus controlled by VE.BUS
Do you measure the voltage and small current to the DC system on the load side of the BP with the DC system completely (physically) disconnected from it?
If yes the BP is broken, if not:
Do any AC lines (or something that works like one, which could in theory be the cabling between PV panels and an MPPT simply oscillating its step-down regulator, creating changes in the energy flow inside the solar cables, creating an alternating magnetic field, creating inductive coupling into the DC system) run in parallel to the DC distribution cables?
Basically: can can you measure what you see also when there is no shore power connection and any MPPT (or similar) is off?
In case of me following red herrings and the BP being broken another wild guess:
Could there be some other devices on the DC-Loads side of the battery protect that could (at least in theory) create similar effects as inverters and kill the BP… like f.ex. an isolated DC-DC converter to charge another battery bank?
I do not have a precise measurement of mA that flows through, my bid is 50-200mA or less, it is only enough for the LED lamps to light very dimly, nothing else in the boat works or can be controlled.
When the load terminal is disconnected on the BP, this stops.
When the BP is replaced with a new one, everything works as it should again.
For me, this indicates that induction from AC cables is unlikely, the boat is built with separate routing paths (starboard and port side) and combined conduit is not the case. According to the established rules in the area
Solar cells are connected the same way on the Multiplus, before the BP and no current flows backwards in the BP. MPPT is controlled by DVCC
Shore power connection or not has no influence
When the fuse after the BP for consumption is disconnected, it also goes out, which once again confirms that there is no current in the DC system.
This only confirms that the BP is defective.
Anyone else experiencing that Smart BP has a short lifespan and behaves as I described?
