With a similar setup in a converted Lindberg trawler, I get a good hour and a bit. A lot "depends" - higher capacity AAs last longer, constant flat out will shorten run time. Its a mile round "my" lake, and it will take me for a walk round, then allow a reasonable time to mess about when I get back to the start. I was using 1000mAH cells, that capacity being the state of the art at the time. Newer ones are likely to be much higher.