ok so a quick background...
we have an off grid cabin... we use very very little electricity there. we currently have 200w of panels through a pwm controller charging a traditional 12v marine deep cycle battery. it meets our needs 9 months out of the year. during the summer that sucker is topped off by 9am. we typically use 40ah in a 4 day weekend between our led lights, cell phone chargers, radio, and our 12v pump. about 100 yards away i have a pavilion with 100w of panels and another deep cycle battery that runs led lights and car radio. again... plenty of power to get that thing topped off within an hour of sunrise.
now, i mentioned the 9 months.... well the other 3 months, we have a trifecta of things that stress the cabin's system... 1, shorter daylight, so less charging, 2 its cold out so we arent hanging at the pavilion, so we are in the cabin the whole time, and 3. we are using a lot more lights in the cabin...
so in the winter during hunting season we end up dropping the voltage down to 12v and we get nervous and start using propane lanterns. not ideal.
but... we dont use the pavilion at all in the winter. so i was thinking i could move the battery up from there to cover our extra needs during those 3 winter weekends we go up there. we have figured out that a water pump and one other circuit is almost always close to half of our load. so we could easily move a pair of leads to the other battery on the "load" end of things... but for charging... how could we wire it so it kept the batteries isolated so they dont kill each other, but still both get the same amount of charge from the panels?
we also plan on adding a 3rd 100w panel at the cabin. our controller can handle 4.
thanks a lot for your advice!
we have an off grid cabin... we use very very little electricity there. we currently have 200w of panels through a pwm controller charging a traditional 12v marine deep cycle battery. it meets our needs 9 months out of the year. during the summer that sucker is topped off by 9am. we typically use 40ah in a 4 day weekend between our led lights, cell phone chargers, radio, and our 12v pump. about 100 yards away i have a pavilion with 100w of panels and another deep cycle battery that runs led lights and car radio. again... plenty of power to get that thing topped off within an hour of sunrise.
now, i mentioned the 9 months.... well the other 3 months, we have a trifecta of things that stress the cabin's system... 1, shorter daylight, so less charging, 2 its cold out so we arent hanging at the pavilion, so we are in the cabin the whole time, and 3. we are using a lot more lights in the cabin...
so in the winter during hunting season we end up dropping the voltage down to 12v and we get nervous and start using propane lanterns. not ideal.
but... we dont use the pavilion at all in the winter. so i was thinking i could move the battery up from there to cover our extra needs during those 3 winter weekends we go up there. we have figured out that a water pump and one other circuit is almost always close to half of our load. so we could easily move a pair of leads to the other battery on the "load" end of things... but for charging... how could we wire it so it kept the batteries isolated so they dont kill each other, but still both get the same amount of charge from the panels?
we also plan on adding a 3rd 100w panel at the cabin. our controller can handle 4.
thanks a lot for your advice!
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