I bought 4 of the Gorilla ones from the states, the idea is great, however they lack a bit of oomph.
The battery pack easily clicks on and pressurises the air, not pump the liquid.
The lances they come with are pretty crap, just looking for some better ones.
Used 1 for a week now and still have not had to recharge it, they also come with an in car charger.
If battery goes flat, you still have the manual pump, when you have to refill you lose all pressure obviously, I then use the manual pump to get up to pressure, battery kicks in after about a minute, runs constantly as the liquid amount gets less.
They come in 9.5lt or 2.5 US galls or 1.5 US gallons.
Going to try a different spray tip to up the flow, and see if it keeps up, definitely slower than a hydra force
Andrew