Hi, my old pacelite have some problems.
the three lights (Full, half and empty) are blinking when I connect the pacelite.
Also I can not charge the batteries.
This sounds like old or worn out batteries to me. I am not able to find any information on what the scooter is saying when all three lights are blinking at the same time. However I have a feeling that the three blinking lights are indicating that the battery pack Voltage is too low for the scooter to operate. This would coincide with the batteries not being able to be recharged.
I recommend to test the Voltage of each battery. Each battery should have around 12.8 Volts in them. If their Voltages are very low that indicates that the batteries are old and need to be replaced. If they have between 11 Volts and 12.8 Volts in them then they could still be bad and dropping Voltage under load, so I would load test them to see if they are dropping too much Voltage under load.
Lead acid electric scooter batteries only last around 300 recharge and discharge cycles, or 2 to 3 years whether they are being used or not. They also need to be recharged every 30 days otherwise they will self discharge and possibly need replacement after several months of not being recharged.
We have a battery pack load testing guide at this link: http://www.electricscooterparts.com/loadtest
Please let us know how it goes and if you have any questions.