I'm at the end of having any idea what to do next. Here's the setup...
Victron Multiplus 12/ 3000/ 120
Smart Solar MPPT 150/100
Shunt
4 Battleborn 100ah Batteries
4 325W solar panels
This is installed in a 2004 Tiffin Phaeton
Connected to shore power
Solar is switched off for testing Multiplus
I am 67 and have an extensive electronics background
The Issue
The past several months, and it seems like this happened after installing a BIM in place of the charging relay, the Multiplus will run as expected for roughly 48 hours. After that, the charging stops, and batteries begin to discharge.
If I switch off the Multiplus - or disconnect it from shore power - for a few minutes, the Multiplus will begin charging again (Bulk @14.4v) for several hours and then drop to 13.56V. Eventually, I will see there is a zero amp draw, even with all our equipment running, it occasionally drops to -.5a for a short time and returns again to zero. Batteries are then fully charged and all 12v systems we have running are supplied by shore power.
It will stay this way for 36~48 hours and then, a 7 or 8 amp draw shows up, the system stops charging, and the process repeats.
Looking at the color monitor, the marching dots show the Multiplus is supplying power to all A/C. However, the batteries are actually supplying the power because they are quickly being drained.
If I disconnect from shore power, there is a change in the display. Marching dots from batteries to the inverter to coach outlets.
Reconnecting shore power, the inverter starts charging again. Marching dots to a/c load and also to batteries (bulk charging at this moment).
Smart Solar voltage: 13.22v
BMV Voltage: 13.02v
Shouldn't these be the same???
What I've Tried
For starters, I fully disconnected the BIM. The charging system seems to remain fully active for days. I reconnect it, and within roughly 36 hours or so, the Multiplus charging stops. At that point, I switch it off and on or switch shore power off and on at the receptacle... Ready to run again for a few days.
Like you reading this, I thought the BIM was the issue - and maybe it is. But what I have been told about this device tells me it is either switch on or it is not. I have checked dozens of times. It is switched off. That mentioned, it will occasionally click on for a brief time (less than a minute) and switch off. I'm told this is expected and would not cause the issues we have.
I removed each battery to check voltage. Fully charged, 13.56v. During discharge, it goes as low as 11.8v.
As I write this, there is a strange 5.8 amp draw, though nothing has been switched on and different since noon today when all was well and the draw was 0.5 amps. Currently, my voltage is 13.06v. The charge shows at 88% and dropping slowly. It was at 100% three hours ago.
The starter battery trickle charge is connected to the starter batteries from the Multiplus. It drops to 12.55v during failure times and returns to 13.49v for a short time, then on to 12.7v when all is working well after a restart.
I have no idea what this issue is. Is the Multiplus faulty? Is the MPPT faulty... though the solar panels are currently switched off, the MPPT is connected. Is this issue due to the BIM we bought from Battleborn?
One final item; The color monitor (Victron) will not show there are any traveling beads going from the inverter to the batteries during the failure. Likewise, while watching the Victron app while all is working correctly, if the amp draw drops below 0 amps the system shifts rapidly from "Infinite" to "nanm" to 10 days. If charging is working correctly, it jumps back to Infinite within a few minutes. However, when it fully fails, ten days drop over a few hours to only a few days or a few hours... all the while connected to shore power.
I simply can't figure out WHAT to look at or test next.
The shore power switch (permanently mounted inside a bay on the coach) is brand new. Shore power, as I have carefully monitored it, never changes at the Multiplus or the pedestal.
I've taken this apart so many times, checked every connection, and carefully reconnected according to the schematic we originally used to install this system...Which worked flawlessly for nearly two years before this happened.
I'm thinking the Multiplus is failing... But how do you test something like this???
Does anyone reading this have any ideas... If so, thanks in advance. I really am at the end of reasoning this out.
Jerry Wills
