Ford Think - Lack of battery endurance

Seeking help with a power issue on my Ford Think.
Acquired a two seater Ford Think. The overall conditions of the batteries were unknown.

I fully charged the batteries and measured the voltage for each battery. Here are the results.
Battery 1 13.90 volts
Battery 2 13.12 volts
Battery 3 13.20 volts
Battery 4 13.16 volts
Battery 5 13.24 volts
Battery 6 13.19 volts
All Batteries in series 79.10 volts

I drove the Ford Think and got unacceptable results. After only 7 miles (22 minutes) the battery indicator on the cluster reflected zero bars and the flashing square box.

When I returned home, I immediately measured the individual batteries again. The second results are reflected below.
Battery 1 12.22 volts
Battery 2 12.14 volts
Battery 3 12.29 volts
Battery 4 12.21 volts
Battery 5 12.24 volts
Battery 6 12.90 volts
All Batteries in series 73.80 volts

I made the decision to replace the batteries with Deka Gel batteries from East Penn.
After installation of the new batteries, they were fully charged. Prior to driving the Think, I measured the voltage on the new batteries. Here are the results.

Battery 1 13.45 volts
Battery 2 13.50 volts
Battery 3 13.37 volts
Battery 4 13.32 volts
Battery 5 13.57 volts
Battery 6 13.49 volts
All Batteries in series 80.40 volts.

I again drove the the Think. Unfortunately, I got the same results. Within 7 miles, the battery indicator on the cluster showed zero bars and a blinking square box.

I recorded the voltage on each battery and got these results.

Battery 1 11.85 volts
Battery 2 11.96 volts
Battery 3 11.90 volts
Battery 4 11.86 volts
Battery 5 12.08 volts
Battery 6 12.03 volts
All Batteries in series 72.10 volts.

Not sure what I should do next. Any trouble shooting advise or other suggestion would be greatly appreciated.

I am having same issue, but haven’t had my meter at home to test voltages I assume they will be similar. I have the old charger but upgraded motor, i am not sure about the controller so I am going to dig into it again this weekend and see. I also have new updated cluster and og factory delta q charger i need to install but need a harness. I will try to update this if I find anything note worthy. I figured I would replace those first since the cluster and charger are both known to cause issues from what I have been reading. I am a newbie so I’ve been trying to read a s much as i can to familiarize myself. this forum has a wealth of knowledge, poke around.

Please email me directly. If we figure it out we can post our solution later.
mikemars@msn.com