My IPilot is Pretty Awesome But....

[Marque]

Ok, so I bought a new boat and it has an I Pilot. I am pretty amazed with it for the most part but there are a few things that have me wondering. The anchor feature is invaluable but if you are in a strong current the motor will basically run non stop anywhere from half to full throttle. This puts some serious drain on the batteries. I have a 36 volt and after 2 to 3 hours the batteries are pretty much drained. This is my first 36 volt so I am not sure if I am asking too much of it or if I have bad batteries. To me it seems like it should have a little more juice than what it has but I due realize it is bucking some serious current holding a heavy boat in place. The batteries are interstates and look to be about a year old. If it is the batteries how do I tell if they are all bad or if its just one? Can you burn these things out running them hard? Anyone have any experience using the anchor feature in a strong current?