More 18650 Shenanigans / Solar Stuff

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So I bought 560 18650 cells.

I'm building another battery. This one is for a solar project. I basically have to live out of my car for work this winter (again). Last year I was looking at just buying a Jackery 1000 and putting a solar panel in my ski rack. My needs were pretty small originally. Just basic phone/computer charging and to run a Chinese Diesel heater. The heater is a knockoff of an Espar or Webasto bunk heater for a semi truck. The power draw to run heater is 10 amps for the glow plug on startup and 2 amps after to run the fan (at 12 volts). I was furloughed after 3 weeks of sub zero car living and didn't buy the Jackery 1000.

This year it was looking like I was going to be forced out of state and living in my car in the summer time so my power needs changed. I started building a battery big enough to run a small 5000 BTU window air conditioner. The window air conditioner draws 350-600 watts an hour depending on how much the compressor is running. So the Jackery 1000 just wasn't going to cut it. It might have been able to keep up with enough solar panels but the Achilles heel of the Jackery 1000 is it is limited to 160 watts max solar input.

After watching a Jehu Garcia youtube video where he was showcasing a new bulk lot of batteries he was flipping I was inspired to build my own battery. I purchased 14 scooter packs from jag35.com (promise I'm not sponsored I just really like what this guy is doing). The packs I bought are gone but he has other similar options on his site. These are some of the best prices per kilowatt for genuine cells I've ever found on the internet. The packs I purchased have 40 LGMH1 18650 cells with a capacity of 3100mAh. I tested 8 of 560 I bought and they all averaged between 3150-3300mAh. I paid $848.80 for 14 packs, it comes out to $1.52 per cell and $132.15 per kilowatt.

I was furloughed in the summer before being forced out of state. (My job is tied to the economy and I have to go where the work is.) I was brought back after a month of furlough and now I'm where I'm at now, being forced out of state. So I need to finish this beast of a project.

The first hurdle I had to overcome was the Sunkko 18650 spot welder I purchased was junk. DO NOT BUY THIS CHINESE SHIT!!! These spot welders are very shoddily built and are only good for 0.1mm nickel strips and 0.2 steel strips. BUY THE kWELD INSTEAD!!! The kWeld is amazing and it allowed me to spot weld the 7s80p battery (with 0.2mm nickel strips) that I'm building without too much trouble. I can get about 30 welds before the welding leads get to hot to touch. This is fine because the battery that it runs off of gets just as hot and should be allowed to cool. The kWeld is basically a very overbuilt mosfet that shorts the battery to get a weld.

The next hurdle was how to get a 1/0 gauge wire to connect to the battery. I used two appropriately sized pieces of copper (that can handle the current) that were drilled and tapped to sandwich the nickel strips. The pictures will help that last sentence make sense. I originally thought I could weld the nickel to the copper but the copper is such a heat sink it doesn't work. Also the drilling and tapping isn't perfectly straight. I'm working with hand tools, my past life machinist self is very disappointed with the workmanship.

Here's basically a rundown of what's going into this battery / solar system. I need to build the box this will live in, these are the pieces that are going into it:

560 cell 7s80p 24V 6.4kWh LGHM1 18650 battery
7s 24V 200A Smart BMS
Victron SmartSolar MPPT 100V 50A Solar Charge Controller
Giandel 24V 3000W Continuous Pure Sine Wave Inverter
AIMS Power 24V 37.5A, 110V Charger (just in case I need to charge this from a generator or something)
Szwengao 12V 40A DC-DC Converter (for the heater and maybe a refrigerator)
3x 200w Rich Solar Panels (the charge controller can handle six of these but I don't have enough room on top of my truck)

This thing is pretty overkill for what I need but I wanted something that can run an 1800w air conditioner AND a 700w microwave at the same time for when I can afford a travel trailer to live in for these out of state excursions. This summer I bought the truck to pull one and until I buy one I'm planning on living in the shell this winter. The truck bed will be a life of luxury compared to my car with more living space, electricity, and a heater. I can't wait for a bathroom and a kitchen in a travel trailer!

01 Cells.jpg
02 kWeld.JPG
03 Top Welded.JPG
04 Bus Bar Open.jpg
05 Bus Bar Closed.jpg
06 Top with Bus Bar.jpg
07 Kapton Tape.JPG
08 Done.JPG
 
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This project just died. I was looking into my BMS and it's not really for this chemistry of battery. The BMS is designed for Lithium Iron Phosphate, not Lithium Ion. It's voltage range is 2.0v-3.7v not 3.0v-4.2v. I can't find a BMS with a high enough amp rating for this chemistry. So I have to start over with a different battery. I guess these cells are going into an electric bike or something.

Also I fucked up and killed about 12 of these cells with a short. Fortunately I broke the pack apart and put the fire out quick enough. I always preach caution with batteries and I should have been paying more attention. While bolting the cables to the terminals for the 5th time today I didn't notice the wrench was wearing the casing on one of the cells. Under the PVC casing the side of the cell is negative and I was bolting the positive on when I wore through. So you can probably guess what happened next.
 
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Stitches

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This project just died. I was looking into my BMS and it's not really for this chemistry of battery. The BMS is designed for Lithium Iron Phosphate, not Lithium Ion. It's voltage range is 2.0v-3.7v not 3.0v-4.2v. I can't find a BMS with a high enough amp rating for this chemistry. So I have to start over with a different battery. I guess these cells are going into an electric bike or something.

Also I fucked up and killed about 12 of these cells with a short. Fortunately I broke the pack apart and put the fire out quick enough. I always preach caution with batteries and I should have been paying more attention. While bolting the cables to the terminals for the 5th time today I didn't notice the wrench was wearing the casing on one of the cells. Under the PVC casing the side of the cell is negative and I was bolting the positive on when I wore through. So you can probably guess what happened next.
Li-ion slabs be like
fire grin.gif
 
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That's a nice project. It is sad that it won't work out.
I wonder why you would need a 1800w air conditionner for a car, it seems a bit to much.
 
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I might have been too panicky when I made my last post because my work from the last 5 months literally went up in smoke. While cleaning up the fire extinguisher mess I assessed the damage and decided to try to salvage this pack. I pulled out the surrounding cells from the burnt ones and put them through a few cycles to make sure they had the same capacity, internal resistance, and didn't get hot. I then replaced the bad cells with some similarly spec'd cells I had on hand. This pack isn't going to be perfectly balanced but it will still be functional.

I'm now testing the BMS to see if it is truly for the wrong chemistry. The BMS I purchased claims to be for Li-Ion but the one I received looks different. So far the BMS didn't disconnect the pack for being 4.2 volts per cell. This gives me hope that it is for the Li-Ion chemistry because if it was for LiFePO4 it should have disconnected for being overvolted at 3.65v per cell. I really wish China wasn't the only place to get affordable electronics. These BMS's have very little documentation and you have to trust what the eBay or AliExpress seller claims the specifications are. The only reason I trusted it in the first place is these are used a lot in the DIY solar communities.

I wonder why you would need a 1800w air conditionner for a car, it seems a bit to much.
I must not have been clear. I have a small 5000 BTU window air conditioner for my car draws 350-600 watts depending on how much the compressor is running. The 1800w air conditioner is for a standard 15,000 BTU RV air conditioner for whenever I buy a travel trailer.

My hope is that the 5000 BTU air conditioner will be able to run for 10-20 hours on the battery (6.4kWh / 350Wh = 18.29h AND 6.4kWh / 600Wh = 10.67h). With 600W of solar on the roof of my car I should be able to run almost continuous. As for the travel trailer with a 15,000 BTU 1800W A/C it will be a losing battle only running about 3 hours (6400Wh / 1800Wh = 3.56h). On the travel trailer I will be able to max out my MPPT solar charge controller with 1200W of solar. So in the best case scenario I'd only be drawing 600Wh from the battery during peak solar input. This isn't sustainable because the battery isn't being allowed to charge and will be depleted in around 10 hours instead of 3 hours (if during those 10 hours I'm getting peak solar which isn't possible).

Any way I'm currently testing the battery. I'm going to cycle it a few times with varying loads to test it's safety after the meltdown and to test the BMS. I'm going to have to add some more high wattage loads to speed the process up.

09 The Fix.jpg
10. Bottom Layer.jPG
11 Testing.JPG



Where does the N64 go? Looks pretty heavy, but also a cool project!
I present the world's first N64 "portable" with a 27 inch CRT and a built in heater. It draws 1.4kWh and should get 4.5 hours of battery life. If I turn the heater off it only draws 60Wh and should get 106 hours of battery life. With the heat off I'm one banana chair away from 101% completing Donkey Kong 64!!!


12 Testing 2.JPG
 
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Hello, don't put the air conditionner, the n64 is definitively better, it will also save space!

I hope your BMS is good, in the listing they said that they can do it for various type of batteries, so maybe it is a hard to see change in the electronics.

I understand more if it is for a RV, I'm not a pro in air conditionner, and it looks standard, but for me reinsulating the RV may give you good result in therm of cooling needed.
 
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My first choice would be to build a travel trailer out of a 6'x12' or 7'x14' cargo trailer because I could go crazy with insulation. R-10 with foam board is 2 inches thick. If I could make 4 inch thick walls look good in the doorways and windows I'd go R-20 all the way around. I'm sure the 5000 BTU A/C could adequately cool a well insulated space that is less than 1000 cubic feet. I designed the battery to run this size of A/C mostly continuously. The only problem is most of these cargo trailers don't have the vertical space, they are usually only 6 feet tall inside. I'm 5'10" and if I insulated the floor and roof I lose about 4"-8" of head room. I found a few cargo trailer manufacturers that allow me to specify the internal height but then they cost more than a travel trailer.

The biggest problem with travel trailers are the ones in my price point have an R value of less than 5 if any at all. And the times when I'm in need of a travel trailer I need one that is move in ready. And as I said the standard 15k BTU at full tilt draws 1800Wh. I choose my inverter off this value thinking maybe I could expand the battery if needed.

In either case I don't want to store the trailer when I'm not using it so it's hard to want to spend the time building or money buy either option. I looked long and hard into vanlife but couldn't find a decent cargo van for the money. I bought an old used truck with a shell to either build the shell into a living space or pull a trailer.

I also don't know if I'm getting shipped out of state in the summer time in the future. This summer was the only time the option came up in the last 3 years of working for this company and that was due to the virus. So the A/C isn't that big of a concern in the long run but solar/battery powered A/C is the holy grail so it's fun to think about. Usually I get forced out of state in the winter for a month or two because the work tapers off. Supposedly in a couple years my seniority will be good enough to not be forced out of state.

TLDR: I haven't made my mind up about anything trailer/vanlife related. However dreaming and scheming is still fun.
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I guess that it would be way easier to insulate a cargo trailer.
What I was thinking of was insulating a regulat RV trailer with non rigid foam, since the ones I've looked at have really thin wall, but it would be way harder for it to look good in the end.
I've only done a light insulation for the van transformation of my sister's Kangoo, but it is not that hot here and since it is for holiday, it is only for sleeping and have the car air conditionner while running.

However it looks like you've looked way more into it than me so I don't want to say to much bullshit.
 
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