I don’t believe that battery is 135ah Bob.
Probably more like 100ah, which is typical for a series 24 battery.
So 100ah divided by 2.7 amps = about 37 hrs. (Pretty close to your 35 prediction)
One caveat however.
You should never discharge a LA battery more than 50%. Otherwise you will damage the battery, significantly reducing its possible lifespan.
This is one contributing factor why LiFePo4 batteries are far superior to LA batteries.
So that 37 hrs realistically becomes 18.5 hrs.