I use a Marine semi traction battery 105 Amps, the specs say you can empty it to 80% of its load many of times, it is about 28 kilo and so big that I sometimes hit the back of my feet against it when I try to pedal
45 miles I already did once, no problemo. Still had 11.50 volts on the meter during the end of the ride, power on, that was about the same when I started. price about 100 pounds.
I'm going to swap it for a 80 amps version because it is about an inch shorter. And obviously shorter.
There is a 55 amps version also that costs 55 pounds weights about 16 kilo.
Going to try that one for my second C5 that currently drives on a 80amps car battery. Car battery goes faster when its full but drops speed gradually. And they tell me that its bad to empty it more then 50%. Kills the battery.
Frank
info@C5Alive.co.uk