You are safe for 10 minutes of fan and water pump, more than that is a risk. I forgot the water pump on once in the staging lanes during Drag Week. There was a long down time, maybe 1/2 hour or 45 minutes and I went wandering around. When I got back it wouldn't start. It did not get so low that it locked up the battery. A jumper pack started the car to make the pass. I had the special charger in the pit area, along with a jumper pack that has a 110 volt inverter, so I used that to give the battery a good charge.