If you have a volt meter and can easily get to your trolling motor battery, you can put numbers to the lights on your minn kota. As Coho said, trolling motor off. For my motor, four is 12.8v or better, three lights is 12.6v two, 12.5, and one light is 12.3v. Running your battery below 12.3 will shorten the life of your battery, if you do it often. I use a product called a Stealth Charger that charges my trolling batteries as well as my main battery while I am running on the main motor (Honda 50hp). I can run the trolling motor (55lb thrust iPilot 12v with two batteries in parallel) for an entire week with the only requirement being that I take a long run on the main motor at least once a day. Easy chore at Lake Powell. The stealth comes with a dash mounted volt meter that will show me the state of my trolling motor batteries in real time, before during and after a long run on the outboard. After a week, my batteries usually drop down to around 12. 5v. If I had a bigger outboard amp output, I could probably go indefinitely, assuming I was taking long runs. This is probably more than you wanted to know but maybe this might be interesting to someone trying to get the most time out of their batteries.