question

Sufficeguy avatar image

No Current or Load shown BMV 712

System has been installed and working perfectly for about a year now. However, a few weeks ago after the battery bank was fully discharged once, now the bmv will not show any current or load, positive or negative, despite DC or AC draw occurring, or when connected to shore power.


Pic of the BMV showing now draw positive or negative (appliances are on):



The MPPT shows only a small current coming in. Also, the solar doesnt seem to take in more than 20 watts or so at any given time, even under addition load that I think would call for it. Pic:


When I turn on a load, like the DC LED lights for example, the voltage on the battery bank drops significantly for a short period. See pic of LED lights turned on and voltage drop for a few seconds:


When I do the same for a more significant load, like the maxxair fan, the voltage drop is more significant and lasts a bit longer before stabalizing (60-120 seconds).



Keep in mind no changes to the wiring has occurred, and the system worked perfectly for a year. Could the mppt have gone bad or the BMV or both due to the full discharge cycle that occurred? The batteries are Lithium from Battleborn. Could the surge on the batteries when applying a load indicate damaged batteries?


Thanks in advance

MPPT - Solar Charge ControllerBMV Battery MonitorLithium Batterycharge controller error
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Given that the voltage sown for the 'start batery' are dropping in accordance wjth the main battery, I would look for a bad connection or crimp sonewhere.

1 Answer
Justin Cook - Bay Marine Supply USA avatar image

@Sufficeguy I suggest checking the inline fuse on the shunt PCB power supply wire... I've seen instances in which one "half-blows", meaning it still passes enough current through to keep the monitor powered, but not enough to let the PCB operate properly... meaning that it sends inaccurate or garbage data to the display head. Given your description of the issue and the particularly odd readings from both the start battery and your house bank, it looks to me like it's most likely a PCB issue, which -while the PCB itself may have gone bad- is very possibly caused by the PCB failing to get a clean voltage from its power supply wire, ie a partially blown or corroded fuse.

Make sure the inline fuse is a 1A quickblow rather than the old 100mA that they used to ship with - it's been determined that the 100mA can tend to drop voltage under load, which can cause garbage readings. Also check the contact points inside the fuse holder itself to be sure they're clean; the slightest buildup of rust or corrosion inside can cause erratic readings.

If the problem persists, I'd contact the Victron distributor from whom you purchased the unit, as it's very possible that the PCB has gone bad and should be replaced under warranty; it's also possible that the display head has gone bad, or rather the data processing of the head. The good news, of course, is that you can leave the shunt itself in place so that your system stays operational.

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