Batteries discharging totally when they get to 50%

I have a problem when the batteries get to around 50% they just completely discharge. Can anybody help please.

compared today to yesterday - there should be no difference in usage

I believe you have three separate batteries. Are they all running the same version of the firmware? Getting them mismatched can be a problem.

I'm not quite sure how you can find out with standard tools - does the portal report that detail? If not, and you have Android, you can use the third-party app https://givenergymonitor.wixsite.com/tutorials

Ah - I see one of them started the day on only 20% charge. I guess as soon as it got to the minimum, all batteries had to stop discharging. ie the batteries had become quite severely out of balance.