Three deep cycle marine batteries were just not providing enough reserve capacity. They charged quickly and on sunny days were fully charged by 9am even in the winter. After dark, they drained quickly, too. Time to upgrade. Research showed a good battery for the money is a golf cart battery. They are rated at 215 AH, 6 volts each, and sell for $89.99 at Batteries Plus. We purchased two pairs and wired them in series/parallel to provide a rating of 430 AH capacity at 12 volts. We didn’t run out of juice nearly as early at night but the first snow storm proved we needed still more. Running without recharging for 3 days was impossible even with 430 AH. Next purchase was a Morningstar Sunsaver Duo solar controller to replace the Sunsaver SS-20L. The new controller allows two banks of batteries, meaning we can combine the golf cart batteries and the original deep cycle marine batteries. We’re waiting for the next snow storm to see if this was the correct decision. Here’s a current peek inside the shed. The batteries are on the floor on the right hand side.
The Sunsaver Duo controller comes with a bonus. It has a data port that provides information about the battery’s state of charge. An adapter has been added that provides Web access and we can now see how much battery capacity remains any time.
After a few weeks of operation the new battery arrangement seems to be a success. The radio bank and the peripheral bank both reach float before noon on a sunny day and neither bank has dropped below 12.0 volts during stormy spells.