nbleak21,
Please give us the location for the source if that information. Qty of AGM cells and AH, temperature testing, etc. I didn't run across that info on the
ECA Systems site, though it could be there.
If you're new here you might still be able to type it in as plain text, or pm me and I'll post it here.
I think a 20 minute duration of assist could be fine because in most driving the system will oscillate between assist and charge modes due to vehicle speed changes and braking events. You only would need a much longer assist if recharging from a wall outlet and intending to use assist mode full time or nearly full time.