Nissan Leaf 48v Off-Grid Solar Project

[Fukuokian]

I don't think not2bme was arguing against active temperature management, he is just using a space heater and a temp controller for simplicity.

That's ok, I was just explaining why I'm not taking this simple route. (I did consider it though.) If other people happen across this thread, they'll be able to have a bit more information as to why it might be good to keep your batteries within an optimal temperature range. For me, battery longevity is very important so I'm highlighting that as a reason for looking into different, more complicated, temperature management systems.

 

[not2bme]

My shed also houses the inverter and mppt controllers so it keeps the temp at above 10C. It's only when the temp outside drops below -10C then my space heater kicks in for short periods of time. My shed is insulated.

Apologies I think I may have mislead you with above sentence thinking that I operate at -10C to 10C. My batteries are kept at/or above 10C during the winters. The shed self sustains its temp due to the heat loss from my inverter and controllers. It's only when the temp outside drops below -10C when my shed will now drop below my optimal temp and the space heater kicks in to maintain the 10C (or if you want to be exact, 10C to 12C). So it's always at optimal range for charging and discharging during winters. (summers on the other hand is a different story!)

 

[Fukuokian]

Apologies I think I may have mislead you with above sentence thinking that I operate at -10C to 10C. My batteries are kept at/or above 10C during the winters. The shed self sustains its temp due to the heat loss from my inverter and controllers. It's only when the temp outside drops below -10C when my shed will now drop below my optimal temp and the space heater kicks in to maintain the 10C (or if you want to be exact, 10C to 12C). So it's always at optimal range for charging and discharging during winters. (summers on the other hand is a different story!)

Ah that makes more sense. That's a much better range

 

[Fukuokian]

Well the weather is warming so time to begin working... I got the reefer box moved onto it's pad. I'm still deciding whether or not to put it on a bunch of concrete blocks (right of the box), or just run a bead of silicon were the box meets the cement. Leaning towards the latter, because it will distribute the weight more directly to the pad. (not sure the structural support in the floor.)

I also checked the voltages on all the modules, which are stacked under compression, but not connected together. After 1 year (really??) they've hardly discharged. I think I charged them each module to 7.8v (~3.9v each side) then parallel connected 7 stacks of 13. I hafta dig through my records, but I think they were at around 3.89v each side after parallel connected for a couple of days. Now they're between 3.872 and 3.860 (I'll post the voltages when I get them in a spreadsheet.

I need to rig up locks for the two doors. The oem ones are way too expensive to replace everything (there's no key codes anywhere--not even on the cylinders. They were also definitely specially keyed on order, as the standard keys don't fit.)

Looking forward to getting my modules in the box, and solar panels on the roof. *** hopefully this spring ***

 

[Korishan]

I'm still deciding whether or not to put it on a bunch of concrete blocks (right of the box), or just run a bead of silicon were the box meets the cement

Why would you put a bead of silicon? What's the purpose here? If you're trying to keep moisture from getting under the container, that's not going to be possible and putting the bead could actually "lock in" moisture to keep it from escaping. Concrete is extremely porous. Moisture will be pulled up through it and collect on the bottom of the container. The moisture will stay there as the metal will generally cool faster than the concrete keeping it condensed there.
If you want to keep it dry under the container, I would recommend putting it up on small pads. There doesn't need to be much space, even 1" would be plenty. You could just take some metal shims and put under the various points. That would allow air to flow under the unit and get the water to evaporate.
Then maybe for some extra protection to keep critters/debris from getting up underneath is to put some screen material around the edge.

 

[Fukuokian]

Why would you put a bead of silicon? What's the purpose here? If you're trying to keep moisture from getting under the container, that's not going to be possible and putting the bead could actually "lock in" moisture to keep it from escaping. Concrete is extremely porous. Moisture will be pulled up through it and collect on the bottom of the container. The moisture will stay there as the metal will generally cool faster than the concrete keeping it condensed there.
If you want to keep it dry under the container, I would recommend putting it up on small pads. There doesn't need to be much space, even 1" would be plenty. You could just take some metal shims and put under the various points. That would allow air to flow under the unit and get the water to evaporate.
Then maybe for some extra protection to keep critters/debris from getting up underneath is to put some screen material around the edge.

The pad has a slight incline, so I was thinking of siliconing the upper part and the sides of the incline. The downslope side I can leave to allow any trapped moisture/water a way out. I'm hesitant to put it on anything because I'm not sure what the structure of the floor is like. I suspect that it relies more on the truck bed to provide distribution of cargo weight.

That said, I now understand what you're saying about concrete being porous and wicking moisture up... You're absolutely right (thanks), my idea won't work.

How does this sound? I might put a plywood sheet inside the box first, then pressure treated plywood under, with the 2 inch blocks underneath that.

(edit: looking into the pressure treated plywood, it's not good because it will likely react with the metal floor.... it may need a membrane between it and the bottom of the reefer truck.)

(2nd edit: marine grade plywood would work... no reaction)

 

[Korishan]

Without seeing the under side of the box, not sure. But generally speaking those boxes are self contained as they are meant to be transported and disconnected, even with product inside. So they should be strong enough to hold weight inside if lifted up.

I would not put wood under the box at all, even pressure treated. All wood will eventually rot, it just takes time. I would recommend putting either metal shims or concrete pads/bricks no smaller than 6" and probably 2" tall. Maybe even use both methods. On the concrete pad put the brick, then put the metal shim on top of that, and the box on top of that. The shim allows for weigh distribution across the whole brick. Use a piece of metal about least 1/8" thick, or 16gauge. That will allow for great distribution.

The bricks will allow for good airflow and keep moisture from collecting.

Inside if you want to add some extra support you could just lay down some 1/2" plywood. If you want even more support put down 2 layers of 7/16. The second layer is offset by a half sheet from the lower and screwed together would be sufficient. You could probably use OSB for the lower level to save a little money. But I would use plywood for the top layer if it's exposed to the inside. If there'll be a top on it to seal it or it's painted, then 2 layers of OSB would be fine. OSB is about half or more cheaper than plywood of the same size/thickness. OSB ($14) vs Plywood ($25) here in Fl for a 4x8 sheets.

Can you tip the box back and take pics so we can see what the understructure looks like?

 

[Fukuokian]

Can you tip the box back and take pics so we can see what the understructure looks like?

I'm guessing it's aluminum panel sandwiched with insulation....

Nissan Leaf 48v Off-Grid Solar Project

Also, just noticed that starting at the midpoint you are running the conduit along the beam, effectively limiting some some airflow., and at the bend it is touching insulation? (Not sure by the angle). I have no idea if that would be enough to cause temperature variations... However, it's a...

secondlifestorage.com

I'm pretty sure it's designed not to be removed like a shipping container. that's why I'm worried about the floor structure.

 

[Fukuokian]

Oh, the striped lines on the underside are from the bed of the truck I used to transport it, so I'm still not sure what the actual floor support is like. I'm about 90% sure it relies on the truck bed to distribute the weight. That's why I was thinking about plywood (I edited one of previous posts to indicate that marine grade might work, but pressure treated is likely to react.) to act in the same manner as the truck bed.

 

[Korishan]

Took me a few seconds to realize that the first picture was the box on its end Ok, yeah, bottom is flat. Also looks like it's completely wrapped in the same materials, aluminum edging and aluminum siding. So you may actually be fine sitting it flat on the concrete pad. I was thinking the box had some amount of iron on the bottom for support.

It already has spacing for drainage (green arrows). So it is designed to be supported on the ends (red arrows). So you wouldn't need to worry about weight distribution. It's already secure enough to be stand alone.

Altho, if you want to add some more support, then the plywood would be fine.

To check if the floor flexes at all, take a string and tape it across the length of the box in the middle about half way up. Then measure from floor to the string. Then take some heavy loads like concrete blocks/bags/etc in the center and measure periodically and see how much it flexes. If you put 200lbs and it flexes less than half an inch, don't worry about it as most of your weight will be on the perimeter anyways.

Altho really, most of your weight will be on the walls anyways, so might not be a big issue overall.

 

[Fukuokian]

To check if the floor flexes at all, take a string and tape it across the length of the box in the middle about half way up. Then measure from floor to the string. Then take some heavy loads like concrete blocks/bags/etc

Yeah there's a little bit of flex with my weight... I have some plywood I'll paint and use under the module stacks inside the box. (The stacks use the compression plates from the original leaf batteries) They'll be against the side wall and back wall in an L shape. I found some original operating instructions from a similar reefer box that said to use pallets or plywood if carrying heavy cargo.

Thanks for your replies! I'll keep updating as I work through it.

 

[Fukuokian]

After doing some more research, the floor of my box should have two long support rails within the floor. I'll use a rubber mallet to confirm their location and align the cement blocks under them, with rubber shims so there's no direct concrete to aluminum contact. I'll also put blocks under the corners and along the sides. I've got 532kg of batteries, plus the weight of the box and any other electronics I add. It'll be around 850kg load (just under 2000 pounds).

 

[Fukuokian]

I'll also try to put the battery stacks (inside the box) over the rails.

Careful: if your concrete pad is uneven or dirty, thinner pavers could snap under a heavy load. Standard 8" hollow cinder blocks (placed with holes facing up) are a better choice than thinner pavers. I'll clean and level the surface as much as I can and use more pavers than necessary to mitigate the risk.

 

[Korishan]

Yeah, a lot of ppl make the mistake of putting the square blocks withe flat side up Because they want a flat surface. Sheesh. That's a recipe for cracked blocks really quick.
They make 4" thick pavers too, so you could go that route. What gets me (at least this is in my area) is the 12x12x2 pavers cost $2. Go to 6x4x4 and the cost jumps to $4 Why would making a "smaller" block cost "more"??? I don't get it. So for my ground mount unit I'm using the bigger 12x12x2 pavers. Gives me room to work with in case any of them crack.

Rubber mallet to the rescue!!!

 

[kje]

Well the weather is warming so time to begin working... I got the reefer box moved onto it's pad. I'm still deciding whether or not to put it on a bunch of concrete blocks (right of the box), or just run a bead of silicon were the box meets the cement. Leaning towards the latter, because it will distribute the weight more directly to the pad. (not sure the structural support in the floor.)

I also checked the voltages on all the modules, which are stacked under compression, but not connected together. After 1 year (really??) they've hardly discharged. I think I charged them each module to 7.8v (~3.9v each side) then parallel connected 7 stacks of 13. I hafta dig through my records, but I think they were at around 3.89v each side after parallel connected for a couple of days. Now they're between 3.872 and 3.860 (I'll post the voltages when I get them in a spreadsheet.

I need to rig up locks for the two doors. The oem ones are way too expensive to replace everything (there's no key codes anywhere--not even on the cylinders. They were also definitely specially keyed on order, as the standard keys don't fit.)

Looking forward to getting my modules in the box, and solar panels on the roof. *** hopefully this spring ***

Great.

Looking forward to see the progression. How big is the container? Have you considered building a battery shed with the container inside?

 

[Fukuokian]

Great.

Looking forward to see the progression. How big is the container? Have you considered building a battery shed with the container inside?

Exterior dimensions are about 186cm x 141cm. (knock 9cm off these for interior space) My first thought was to build a battery shed, but I decided this was easier and perhaps cheaper in the long run ... so it is my battery shed. I like that it's already insulated, and well sealed. I just have to cut some ventilation holes for some temperature controlled fans for summertime.

 

[Fukuokian]

Found these foundation support spacers for $1 USD each. They're designed to support house walls, so it's safe to say they'll handle my battery box.

 

[kje]

Exterior dimensions are about 186cm x 141cm. (knock 9cm off these for interior space) My first thought was to build a battery shed, but I decided this was easier and perhaps cheaper in the long run ... so it is my battery shed. I like that it's already insulated, and well sealed. I just have to cut some ventilation holes for some temperature controlled fans for summertime.

I see.Did you buy the container used?

 

[Fukuokian]

I see.Did you buy the container used?

Yep! ($230usd)

 

[Fukuokian]

Purchased my solar panel mounting rails. I can't afford aluminum rails, so I went with steel angle iron for shelving. (similar to this, https://www.amazon.co.jp/-/en/Perforated-Single-Double-Garden-Bracket/dp/B09MQNYRZL) Paid about $12.25 for each 2400mm rail. (2.62 yards) I used this style for mounting my first 2 panels; I painted them and they have held up very well. I used white vinegar to clean and etch the surface, dried them, then applied a good quality oil based rust paint. Likewise for the brackets which I custom bent (see previous posts)

Strangely, the 40mm x 40mm lengths are priced the same as 30mm x 30mm. I used the former for the first 2 rails, but went with the latter for the 8 new rails I just purchased. I want to keep the weight down, and the smaller rails are plenty strong enough. One slight hiccup though, the brackets have have holes that line up perfectly for bolting to the first set of rails, but not for the new ones. So... I built a little jig, and drilled and extended the existing holes for the 14 new brackets. Now I just have to paint everything.

If anyone is thinking of using similar rails, make sure your roof can support the total weight of rails, mounts and panels. I calculated each of my brackets will see a 30-45kg load. (The lower rails and mounts support more weight than the upper ones due to the incline of the roof/panels.) I have a cement tiled roof, with some pretty heavy duty framing/supports in the attic. Even so, I may add some extra bracing.