Sudden increase in drain on batteries
 

Good morning,

I have just bought a 2014 Par Car with 8x6v T105's that were installed in February 2017.

The batteries were fully charged and I drove nine miles with the charge meter rarely dropping below the line between green and white.

Suddenly the needle went almost into the red zone and stayed at that bottom end of the green for the final mile home.

I plugged in the charger and it showed the batteries to be 80% drained (after driving just ten miles) but then they took less than an hour to charge fully.

After charging, I tested the voltage across each battery and they were all around 6.7v. I also checked the water levels and they were all okay.

Three questions:
1) Why would two year old batteries only give me ten miles of travel?
2) What could cause a sudden increase in battery drain?
3) Why were they so quick to fully recharge from being 80% discharged?

Thank you.