I have never had dead batteries. As one guy mentioned, I just plug mine in when I get home. For $200 I have a 3-bank charging system on my boat; I simply plug an extension cord to the 3-bank and all 3 batteries are charged. Not trying to suggest alternatives to your product, but for the money conservative boater out there which there are many, would a power inverter work for those guys who already have an installed charger on their boat? I have a simple power inverter on my truck wired to the truck battery. The power inverter has a fuse on it. You can pick those up for $50 ($100 will get you one that you could run a tablesaw and cord drill on). I am no expert on this and wouldn’t suggest doing this without proper research on the amps pulled from the charger, etc., but for those with a charger already installed, $70 for a power inverter and an extension cord may do the trick.

This is a copy of a reply I made to the LMS-480 thread regarding the same error. Probably the same cause.

I too have the LMS-480 and think it is great. Like most of you here I too had the sonar locking issue and “GPS Module Not Responding” error. I’ll tell you from experience with the error that your unit is most likely FINE. Here is what Lowrance told me to do which worked twice. (I’ve never had to sent unit back). The receiver is on a separate power supply than the unit. The receiver, therefore, does not turn off when the unit is off. Sometimes the receiver needs rebooting. Unfortunately the engineers at Lowrance did not put a button or something on the receiver antennae to do this automatically so you have to remove the power wire for 3 minutes then reconnect it. It is the red wire labeled NMEA-2000 according to them. I located wire, pulled hair out trying to figure out how to unhook it and then get it hooked back up so a case of the smarts hit me and I just unhooked everything from the battery. This fixed it both times. Most likely that is all that you need to do. Other than this mild nuissance the unit is superb and I haven’t had any additional issues with it after patching the software. I am ready next time for the receiver error though. I bought a $4 toggle switch from Wal-Mart and mouted it under the dash for the reciever so rebooting it is now just a flip of a switch.

Good luck

I too have the LMS-480 and think it is great. Like most of you here I too had the sonar locking issue and “GPS Module Not Responding” error. I’ll tell you from experience with the error that your unit is most likely FINE. Here is what Lowrance told me to do which worked twice. (I’ve never had to sent unit back). The receiver is on a separate power supply than the unit. The receiver, therefore, does not turn off when the unit is off. Sometimes the receiver needs rebooting. Unfortunately the engineers at Lowrance did not put a button or something on the receiver antennae to do this automatically so you have to remove the power wire for 3 minutes then reconnect it. It is the red wire labeled NMEA-2000 according to them. I located wire, pulled hair out trying to figure out how to unhook it and then get it hooked back up so a case of the smarts hit me and I just unhooked everything from the battery. This fixed it both times. Most likely that is all that you need to do. Other than this mild nuissance the unit is superb and I haven’t had any additional issues with it after patching the software. I am ready next time for the receiver error though. I bought a $4 toggle switch from Wal-Mart and mouted it under the dash for the reciever so rebooting it is now just a flip of a switch.

Good luck