It was working nicely with my 4 AGM batteries. But, after I changed them out for 4 LiFePO4 batteries with BMS, it has gone dark.
I measure 13.4 volts on the red wire at the shunt PCB.
I’ve swapped out the display portion with no change in symptoms.
I suppose my next step should be to buy a new shunt PCBoard for $22 on Ebay. But, there appears to be only 3 components on that board: 1 tiny capacitor and 2 box capacitors.
If one of those went bad, could it cause the display to go dark?
There is also the RJ12 connector and cable.
These are subject to water and physical damage.
Closely inspect them.
Also closely inspect the fuse and fuse holder.
Partly blown fuses can pass 12v, but not enough current for the display to run.
Fuse holders are subject to water and physical damage.
I measured the +12 at the point where it connects to the shunt PCB. The display was connected. So, if the red wire was a problem, I would expect to see a voltage drop there. That wasn’t the case, so I have to believe there is nothing wrong with the fuse, fuse holder, or connection to the battery.
Is the shunt PCB known for frequent failures? It seems to be a very simple device.
I can’t find anything wrong with the RJ-11 cable leading to the display module. The contacts are clean. I wasn’t able to remove that cable from where it connects to the shunt PCB. What’s the trick?
Does anybody have a schematic that shows the pinouts of the gray cable? I’d like to put a meter on the end that plugs into the display module.
RJ12 cable pinout
Look closely at the sockets.
Bent or corroded pins.