We are leaving for the BWCA on Friday. I am attempting to find a way to charge my fish finder battery. I have a solar panel that only accepts a USB port. My battery is a 12v with a positive and negative connection. I have searched all over the internet attempting to find a solution. Anyone else have this issue and know how to solve it?? Please help!

Unfortunately your usb solar panel is probably not the correct voltage for your 12v battery.

There are a number of portable solar chargers out there for a 12 volt battery, but one thing I would keep in mind is that if your battery is lead acid/SLA/AGM you may be disappointed with the speed at which it charges off of solar. Lithium batteries like the ones that typically supply USB devices charge much more efficiently. You might be better off just bringing a backup 12v lithium battery/power supply like a car jumpstarter (many can be used as a 12v power supply).