So you still don't believe what you've read? Unless you have a very big solar panel (physical size goes up with output capacity). I have no idea what size panels you have been thinking about but to actually "charge" a battery would require a panel 1/3 the size of your boat. And since you are using the boat during the day one must assume the panel is at the dock. So what's the point. Solar panels are fine if the boat is going to sit for a week while you are at work and then head to the boat for the weekend. But again, unless you have a high capacity panel it will not "charge" the battery like you might expect. Smaller panels are nothing more than battery "maintainers". Think in terms of amps of power used while trolling. A 50# trolling motor will suck about 45 amps of power out of a battery in one hour at its highest setting. Granted, you probably don't run it wide open steady so cut that use in half. So to replace that 20+ amps of consumed power with a solar panel would require one with sufficient capacity to actually charge the battery in the amount of time you have between the next use. Remember we are talking AMPS here, not WATTS. A small 5 WATT panel provides only 1/3 of one amp. So to replace that 20 amps of power would take 60 hours of direct, full sunlight. You can run other capacity numbers to figure what you really need. If you have shore power, an on-board charger is a far better way to handle battery charging. And just so you know, measuring static battery voltage is sort of misleading. Measure the battery voltage with the motor running and it will likely read much less than 12.5 volts if you've been on the lake all day using the motor even intermittently.
