The Full River direct replacement may not be quite so direct. I bought one for my PC625 replacement, it was in a tin case which I had to remove to fit the battery tray in my aircraft, (the actual battery is the same size, but there's no mention of it being in a case!) then I realised that the positive and negative terminal where reversed, so I could not use it due to insufficient battery cable reach - in my aircraft installation - setup for, and only for, the battery sitting a certain way with the terminals out in the breeze. I did not have more cable than it needed. Nope, not even another 150mm. Foiled again. I just went and bought a PC625. I put the Full River into a battery box with a solar panel to power an electric fence. Works GREAT. I used a $30 solar car charge panel on it (in the hangar, ambient light) and got 8 years out of the first one before deciding to change it "just because" - it was still starting AOK after 8 years. I think the solar trickle charge just keeps the battery up, not naturally depleting over time.