I have a pair of 100 Ah deep cycle group 29DC 12V marine batteries connected in parallel as a 200Ah 12V array, that I would like to maintain in sub-freezing weather (-20 to +40°C). These batteries can sit many weeks or months between uses, but are usually fully charged before connecting any maintainer, so the goal really is maintenance rather than charging. Installation is near Philadelphia PA, in full sun in winter, shady in summer (due to trees).
Which model controller and which model solar panel would be recommended, so as to not cause issues with overcharging in this long-term storage scenario? Primary interest is freeze protection, as it is believed keeping a small current flowing during cold nights is best protection in very cold weather.
