I'm working to setup a 12v battery
system for using my 13' trillium
dry most weekends.
As we plan to use the trailer mostly in the winter for skiing, and as much as I would love a solar
system, I don't think it would be viable as we'll be leaving the trailer parked during the week (we wouldn't be able to clear snow from the panels) and it gets pretty dark up here in BC during the winter !
What we're thinking is to have a 12v battery
that we charge up at home during the week and bring up to the trailer for the weekend (generally Friday night or Saturday morning), and bring it home with us to recharge after a weekend of skiing.
I've been reading lots of forums and trying to work out the battery
capacity I would need, but am still a bit lost / would love someone to check my logic / math. Apologies as I'm sure this has been covered over the years.
In terms of loads, we plan to install a a few (2-3) low power LED lights
and to install 2 usb ports to charge our phones. Under typical usage, I could see us getting to the trailer Friday night and using the lights
for a few hours, plugging our phones in for about an hour. Saturday, might use the lights
in the morning for an hour max (often its bright enough to not need them in the morning, but trying to be conservative), then turn lights
on again when returning to the trailer around 5pm. In an extreme case, we might keep the lights on until 1am, and again possibly topping up the phone charge for an hour or two each. We might use the lights in the morning on Sunday again, and typically would head home after skiing. The exception would be for long weekends or if we take an extra day, when we might want another nights worth of light
. Noting this we also have the ability to charge our phones from our car on the way to the hill, bit depending on where we're setup, it may not be for long. FYI we'll be using propane
So - if we assume the loads for worst case scenario as:
= 3 lights x 10W x (4 hrs Friday + 8 hrs Saturday + 8hrs Sunday)
= 30W x 20hrs
Dividing this by 12V to determine amperage:
600W•hrs / 12V
2 phones x 2A draw(?) x 2 hrs / day x 2 days
= 4A x 4hrs
= 16 A•hrs
= 66 A•hrs
Does this make sense? Am I over / underestimating the loads?
If that makes sense - then comes battery selection. I'm slightly confused about deep-cycle batteries, as I've read that these shouldn't be depleted below 50% capacity to maximize their usable life. Does this mean I should be looking for an ~120 A•hr battery based on my calculations? From someone that doesn't know a lot about battery's, this sounds overkill! Are there alternatives to deep cycle batteries for my typical usage? Am I just way off in my assumptions/ methods ?
Finally, as I am open to a solar
system eventually (will use it in the summer too, but I tend to do most of my summer camping / hiking in tents), can I use a generic 12v battery as a part of a solar
Thanks a lot for you help!