[Spruce]

How good will a 12v 35 amp battery from a mobility scooter be for my trolly

Should be fine for the Sureflo.  Pure Freedom fit a 12v 24ah one on their standard trolley. I used to get about a day and a half out of it when running the Sureflo and I forgot to charge it.

PF couple the Shurflo pump with a Spring controller which helps to reduce power consumption.  It also helps that you are constantly aware of not wasting water.  Not wasting water also means power saving as well. The pump also doesn't have to work as much as your hose is much shorter than if you were using a hose reel with 100m of hose on it. 

[jk999]

Mr g what pump do you use