I decided the other afternoon to run to the lake for a few hours, and I hadn't charged the batteries in a few days. The boat started and ran fine but I left all of my HDS units on when I got to my first spot, at least two of which run off of the cranking battery. When I got ready to leave about an hour and a half later the battery was d..e..a..d..Dead. I finally got the cranking battery swapped over with one of the trolling motor batteries and was able to get the boat started but I was getting a low voltage alarm intermittently and eventually lost about half power and had to idle the rest of the way in. I was afraid I had burnt up a coil because I had read somewhere that running with low voltage for very long could do that (which may or may not even be true). So when I got back home I swapped the batteries back around and plugged the charger up. I went back out yesterday to see if there were any lasting problems, and the boat started and ran fine, except for the fact that anytime I hit the trim for more then about a second the voltage would sag and the low voltage alarm would beep until I stopped trimming the motor. I never turned my Lowrances on because I didn't feel like going thru the head ache again. I fished for several hours and the only time I had any sign of trouble was when I would trim up or down. The voltage would go down to about 10 and then when I would stop trimming it would go up to around 11. So my question is this, do you think my battery is just biting the dust or is there a deeper issue here???