PWM Solar system randomly not charging for days and never charging to full

[ma1m]

Hello everyone,

There is currently clearly something wrong with the BlueSolar PWM system in my van, and I’m at my wit’s end trying to determine where the problem lies (I’m living in the van and am currently quite remote, so hard to find places for assistance and thought I’d try it here first - thanks!)

My question: are my batteries dying, is my panel busted, or is this a controller issue? (I apologize if this is too complicated a question; if so, I would love directions for where to take this - much obliged )

Some context:
A few days ago, I woke up to find my PWM BlueSolar controller had shut the system down, because the batteries (2x 100ah lithium) discharged to almost 9%. Weather conditions had been good (very warm and sunny) for weeks, so I was quite surprised to see this in my Smart Shunt data:

The graph is showing a few periods of multiple days of not charging at all (and very random too - charging started again at 4PM the last time this happened). In addition, the daily charge being put into the batteries keeps declining (even though weather conditions are stellar). It says the batteries have actually never really been above 51% charge, and the last few days it seems it’s being “capped” at 17% charge.

I have attempted/tested a few things so far to see if I could determine what’s going on:

Batteries are 2x 100ah Eco-Worthy 12v in parallel - not older than 2.5 years

Solar panel (Victron 185W) voc is around 18-19v, and charge current between 5-8A measured in sunny late afternoon - maybe that’s too low?

Controller says battery capacity is full at 12.9v (when obviously it’s clearly not)

PWM controller is set to b04 / lithium battery settings

Anyone got any ideas? Or directions on where to take this? (I bought the van with the system already built in and don’t know where it was installed, so impossible to get support via that route)

[pwfarnell]

The most common cause of poor charging, especially in boats and vehicles is poor connections, often loose connections from vibration. Check controller to battery wiring, both positive and negative. If there is a loose connection this creates voltage drop so the controller sees a higher voltage and reduces charging. If you have a multimeter check the voltage at the controller terminals and the battery terminals when charging, they should be the same.

Other thoughts, dirty panel, hot panel as output reduces as the panel gets hotter, you have left a load on that you have not found. The above would not cause the controller to delay start up though, hence my money is on wiring issues.