pianotuna wrote:
3 batteries connected in parallel will last more than 3 times as long as using one battery at a time.
x2.
If you have 3 batts already, use them all in parallel. No need to rush for 2*6V either, you can get them later, when these die.
Jack Mayers "Golden Rules" is better for a beginner than Handy Bob's blog. I enjoy reading Bob's rant and agree with most of it, but this is not a good read for a beginner. Maybe only to get you interested. He is not a good educator, let's put it this way.
Bob is not trying to sell you anything, while your dealer is. They take a trailer with 10W panel and 16ga (?) wire from the factory, and add 150W. Easy - yes. Sensible - no.
10W panel is practically useless, might as well get 140W in its place. And another 140W nearby. Total 280W. With PWM controller. For when in storage, 280W will keep your batts full same well as 10W.
2*140W panels.
Again, (is it 3rd time I'm asking about this?) - find out what wire is in there, and what is wire length from roof to proposed controller location.
Important detail: controller should be as close to batteries as possible, somewhere in the front of the trailer. Manufacturers often ignore this rule.
If 2*140W is too much for this wire OR if you don't have enough room, get 2*120W or 2*100W. Anything more than 150W is better, because you do need more.
If the OEM wire is so thin that it can't handle more than 150W, I would cancel this option, and used the money to buy "proper" components and hire a solar installer like AM Solar of whatever you will find. If your dealer is handy enough for that, use him. Most any handyman or electrician will be able to screw 2*120W or 2*140W panels to the roof and run #10 wire to inside.
The above 2*140W kit includes MC4 Y-splitters needed to wire 2 panels together, this is a very common setup. 20ft long box should have enough roof real estate for that.