question

Sorry, just to add that I have checked the fuse in the controller and the 15a inline fuse and both are fine. I can't see any obvious wiring issues. I'll check again. The battery is less than a meter from the controller and the solar panel is about a meter from the controller.

PV has to get 6V above the charge voltage, in the example it isn’t even 2V above so it won’t be able to charge anything.

Your peak PV voltages are also very low, so I suggest you check your panels, cabling etc.

Thank you. Much appreciated.

Disconnect the MPPT charger and measure the OpenCircuit voltage of the panel with a multimeter.

If possible, then you could also measure the short current of the panel, sunshine on the panel would be good for this second measurement.

With this two values, or at least with the open circuit voltage we know if the panel seem ok.

Because for know it looks like the PV power is too low to get the battery charged, that's why the battery might be so low in health...

Thank you all. I did measure the open circuit voltage of the panel yesterday in sun. It was 21v. Does that help?

So, basically the same as measuring the voltage, just setting the multimeter to amps. I'll do that later. There is a bit of sun today.

Yes, your multimeter should be able to measure the current. So please check if you maybe have to swap the connection on your multimeter and select the highest current measurement range (often 10A) the multimeter ofers you.

Then just check there is some sunlight on the PV module and measure the current.

I managed to get hold of the company who supplied the solar panel, through the camper conversion company. Open circuit should be 30v, I got 21 on a cloudy day. Short circuit current is 6amps, but they said they expect this in June time in the UK. Today through the controller with sun on the panel I got 14.06v and short circuit of 3.8 amps. The company think maybe the panel is not functioning.

The reason is due to the battery not seemingly charging, but it has very much had it based on the voltages measured (below)

Hmm, - there is still something weird.

Although the 21V and 3,8A should be fine, the open circuit voltage is normally reached at only little daylight. The current is strongly dependant on the sunlight, the voltage is not. It could be the case, that the voltage of the PV panel drops rapidly when current is drawn. This would match with the results the mppt charger is showing, that the PV voltage is not really high enough as soon the charger tries to pull current out of it.

A weak battery should still reach the absorption voltage of about 14,xxV. It can only store less energy, but still reaches the voltage. So the 12,8V max an the battery shows us, that the battery is not charged.

So in the end thats no rocket science, either the mppt charger is defective or the PV panel is.

With that data I would rather guess the PV panel is causing the problem.

Can you maybe try to connect some other panel? Just to cross check the issue?

Thank you @Jetlag. I will see if I can use another panel and hook it up. Or, better for me, try another controller. I have a separate mppt controller (not victron, but Epever), on a garden room set-up, but I have bolted the panel down, so harder to remove.