This is a very interesting thread. Kudos to the OP for all his hard work. Just a couple of comments, mainly aimed at others who might be contemplating this type of setup, or even parts of it. I too have been looking at job site boxes because they are relatively inexpensive, and are pretty sturdy. I question his comments that they are designed to live outside. They certainly are outside a lot, but most people I know end up storing them indoors when not in use. Many of them never get removed from a truck or trailer due to the weight. First, keep in mind that there is going to be significant condensation, and eventually rust. Only time will tell if his efforts to insulate the boxes, and provide some heating mats will take care of that.
If I was building to the extent he has, I'd incorporate PEX tubing into the slab, and heat a small building with hot water, preferably from a solar panel. It is not difficult. You don't need a lot of heat to keep things dry, and at the right temperature. I've spent a huge amount of time playing with shipping container ideas, but they have gotten very expensive, and a lot of work still has to be done to get them insulated. After penciling out the costs locally, I chose to pour a heated slab, and am building a small utility shed. 8' x 16', with 9' ceilings at the ridge. But I'm in town, not in Maine. I'm envious.....
My situation is, well, a little
weird. We bought a 100+ acre chunk of raw forest, that had as it’s only existing infrastructure a stubby stretch of 150’ of driveway. If we were retrofitting batteries into a place that already had some existing buildings, amenities and such, I’m pretty sure that I’d be doing exactly as you suggest. It’d make more sense. We didn’t know exactly where we were going to build at first, so we needed to be able to
use the batteries (and move them around) well before we’d have the ability to bring in a cement truck, so insulated job boxes made more sense for us. Once we decided on a site and had built some driveway, we gave them a slightly more permanent home. We’ve setup a 20x12 ShelterLogic as a workshop on our build site (down ~950’ of driveway), and have it wired up with lights, outlets and it runs our (220v) well pump. We keep it charged right now with a really simple 2x4 ground mount, and three 375w panels, though we started off by using a little generator.
Next year, we plan to put up a fairly large permanent workshop. The batteries will be moved into or adjacent to the building (but under a roof) at that time. We don’t anticipate leaving them
fully exposed to the elements beyond this year. So far, so good, though. Nothing has gotten wet, dirty, or infested by bugs or furry things to date.
Each of my solar panels will produce an average of about 29k BTU per day. With a heated shed, you don't need the job boxes, you just need strong shelving. Of course, that is not as resistant to theft. For my boiler system, I have a Lithium Titanate 7.5kw system for emergency backup.
Righteous! LTO batteries make a lot of sense for emergencies, since they can be left unheated and still be used. We’ll be looking into something similar for our emergency system.
Another comment, one that I struggle with: maximum battery voltage. I've spoken with tech services at most of the major companies over the last couple of years. When asked about the top acceptable voltage, most of them told me that anything over 60v would cause a lot of over voltage tripping. I too have Victron, but am reconfiguring some of my batteries for 14s, rather than 16s. (NMC) I have no way of qualifying that statement any further, and am not trying to start up a discussion debating that. I'm just telling everyone what techs told me. I personally like the idea of higher voltage, and would rather run in that fashion, but there are few choices that can handle over 60v. (Here in the USA)
We’ve been running our Quattro on 16s (NMC) @ 60v nominal without issue all year long. “Full charge” for us is 64v (4.0v/cell). We monitor the Quattro daily and haven‘t had a single warning / error / trip. We’re on the latest firmware, and haven’t done anything to the unit that the VictronConnect app won’t
let us do. So,
one data point.
We’re still building the house, so we’re mostly running large power tools, pressure washers, lights and the well pump off the system right now. Everything has been functioning well and without complaint. If past is prologue, I don’t see any significant problems cropping up as we add more panels and more loads. We’ll see!
I applaud his work. A lot of effort and thought went into it. Onward and upward!
Thanks! I‘d love to hear more about your setup.