diy solar

diy solar

My $850 720 wh Solar Briefcase (if you don't count the tools)

jpcjtrtj

New Member
Joined
Mar 28, 2021
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113
So, I set out to try to make a battery and duplicate Will's Milk Crate build; but then went on to the briefcase idea as I was wandering the aisles of Harbor Freight. So, here it is. A full supply list and cost is included. This was a fun project and will help me when I'm remote working from the campground next week, and was good prep for my next project of building a 280 AH LiP04 battery for my trailer (cells and BMS on the way . . .But I might go with two Fortune 100 AH instead, so stay tuned for a deal on Eva cells).
63944632361__5A58D148-A045-4FD5-B576-CFCBCE6F62AF copy.jpgIMG_4062 copy.jpg

Battery: Fortune Cells 60AH &BMS Daly 12V 80 Amp 4s
$501.86​
Power Inverter Pure Sine Wave 600Watt 12V DC to 110V 120V with Remote Control Dual AC Outlets and USB Port for RV Car Solar System Emergency
$166.33​
HYCLAT Red 50A 6-10 Gauge Battery Cable Quick Connect Disconnect Plug Wire Harness Plug Connector Recovery Winch Trailer (4 Pack)
$13.04​
ALLPOWERS 20A Solar Charger Controller Solar Panel Battery Intelligent Regulator with USB Port Display 12V/24V
$19.56​
25 Pieces Cable Management Desk Wire Organizer Cable Ties Cord Management Clips
$8.69​
Jtron 6-way RV Fuse Blocks blade box DC 12~32V 12v Fuse Block Holder With LED Indicator Light Kit For Automotive Car Boat Marine Trike (6 way)
$9.78​
P-A000146N - 6" Extension Cord with Flat Rotating Plug - Black
$15.20​
Heavy Duty Double Sided Tape, UPwoktem Mounting Tape Easy Peel Off Waterproof Foam Tape for Car Home Office Decor (16ft X 0.8inch, 5925 Red)
$11.90​
GG Grand General 55261 Red 10-Gauge Primary Wire, 25 Ft
GG Grand General 55260 Black 10-Gauge Primary Wire, 25 Ft
VIGRUE 160PCS Copper Wire Lugs [4 6 8 10 AWG 1/4-5/16] Battery Cable Lug Crimp Wire Connector Ring Terminals with 2:1 Heat Shrink Tubing Assortment Kit
$47.79​
6 AWG Gauge Red + Black Pure Copper Battery Inverter Cables Solar, RV, Car, Boat 4 feet 3/8 + 5/16 in Lugs
$24.35​
Case; APACHE
3800 Weatherproof Protective Case, Large, Black
$32.50​
Total
$851.00​
AC=DC {Power Supply (10 A)
DC Power Supply Variable 3 Digital LED Display Adjustable Regulated Switching Power Supply Digital with Leads Power Cord (30V 10A)
$59.80​
 
Very nice build. I did a build using the same case so its interesting to see a different variation. Love the parts list you provided...thanks for sharing
 
Credit to Will for the basic knowledge and inspiration to get started down this road. And to Rocketman for the way he set up his case. I thought about sawing through the side and putting the plugs on the outside, but it seems like this thing would get hot and running it with it cracked a little would give better airflow. If I can do this, anyone can . . . It could be refined a bit, but for me it's a useful tool.

jps
 
Does anyone have any concerns that the battery is on its side when in use? it can be stood up in storage ....
 
You have 768Wh by the way... depending on your charge parameters. The math is Ah x nominal voltage, which for a 4S LFP bank would be 12.8V
Cool build! I’m sure it is far lighter than mine. I clock in at 2048Wh on mine, so it is a bit heavy to carry.
 
According to the seller, Electriccarparts.com these Fortune packs are fine to use on their side. The only thing they don't like is sitting upside down. . . good to know.
 
So it’s a tiny little project; but I worked off grid all week on line with a computer and monitor with recharges of phones and iPad ... with only 2 100 watt solar panels. I was able to keep the AGMs on the trailer up and running (still over 12.4 V by 6th morning). Capacity check on suitcase was almost 64 AH! Electric Car Parts advertises 60 AH. I’m a fan of the Fortune product.

Latest project is 25 AH 4S Fortune battery for CPAP. 37 AH agm gave me four nights before needing charge; I’m betting this will will give me 5 or 7. Capacity check under way! Fits in a 7x3x5 box; but using a slightly larger box to start.
 

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So, I'm building another one of these for a friend. I'm going to add a connection to use a 5 amp Victron charger to charge off of shore power. Do I need to put a 10amp fuse inline with the charger? As it comes out of the box, the Victron charger comes with a wire that would connect directly to the battery with ring terminals. 5 amps seems like a small current and low fire danger on a stock wire that comes with the charger, and would only be in use when plugged in at home for a day or so.

Thus, I would get rid of the fuse block in the next build and would wire 3 things directly to the 60 AH LIPO4 battery (with 80A BMS):

1. The 20A solar charge controller (with a 25amp inline fuse and 10 AWG wire),
2. The inverter (direct with no fuse using 6 AWG wire (max load is 50 amps), and
3. The wire to plug into the Victron charger (no fuse with wire/connector that came with charger). This would be capped unless it is in use.

Anyone see an issue with this?
 
Please help me understand. If the only thing plugged in to the battery is the charger, how can the battery cause the wires between the battery and the charger to overheat and potentially catch on fire? A short in the charger? Or the wall? Something else?

If that is a potential risk why doesn’t Victron put a fuse on either attachment to the charger? Either the direct ring lug connection or the alligator clips? This is a temporary connection only in place when charging at home…

Thanks in advance for your thoughts.
 
The max draw from the inverter is 50 amps. The max discharge available from the battery through the daly bms is 80 amps.

The max input from the SCC is 20 amps and the charger is 5 amps, hence the 25 and 10 amp fuses respectively.

In wills milk crate build, he fuses the SCC and power supply as above but not the inverter and uses those blade fuses which are rated for only about 1000 amps of interrupt current ability.

If my 12v 60 ah battery is a 4s with each cell having .8 mOhms of internal resistance, the short circuit amperage could be 4000 amps that you need to interrupt in the event of a short circuit? Doesn’t this Require a T fuse from the battery? Seems like 100 amp terminal marine block fuse could work with AIC rating of 10,000 amps
 
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LFP easily gets to T-class fuse territory.

Better to bust 20-40bucks on the fuse than the entire build when the low internal resistance could cause a sustaining arc inside the fuse. Toasty.

I recommend considering T class fuse with LFP capable of such high short circuit amperage as you mention. They pop real fast so if the cable is sized appropriately then the system should reach a safe state quickly with a short.
 
For those of you following along at home . . . After much reading and some hand wringing, I decided to add a main terminal battery fuse to this build. For my setup which will never see more than 50amps (the max pull of the inverter, I went with a 60 amp fuse (because there is no 62.5 amp fuse). For the setup I build for a friend, that could see 65-70 amps (50 from the inverter and 15 from the 12 Volt female socket), I went with a 100 amp fuse. I also fused the inputs for the 20 amp solar charger (25 amps) and the 10 amp Victron charger (15 amps) with simple blade fuses. The short circuit amperage for this 60 AH battery is 4000 amps, less than the 10,000 amp rating of the MBRF fuses.

So, the two additional parts are:

Blue Sea Systems-5178 Battery Terminal Fuse 60-AMP. $15.63

Blue Sea Systems 5191 Fuse Block Terminal 30-300 AMP $21.08

And I found this cool water boiler that will run on 95 Watts on a 12V system for tea or coffee (I haven't tried it yet, but it looks neato:

Bamjour 420ml 12V / 24V Car Electric Kettle, 95W Portable Stainless Steel Travel Car Mug Hot Water Kettle Electric Mug Kettle for Tea, Coffee Water Heating(Black) $33.19
 
Best I can do with a Victron 5 amp charger is $895. . . I suppose I could go cheaper and try to get cells from China, but I love the ease of the fortune batteries. 2 solar panels adds another $190.

I really like the portability of your box and having the plugs on the outside. I thought about doing that when I saw what you did (I even bought that strip), but the mid sized Apache briefcase is not quite big enough (so returned the extension strip back to Amazon). If I went the next size up, I could do that. On the other hand, the way mine is set up, you have to leave the top open which ensures no heat issues . . .
 
You have 768Wh by the way... depending on your charge parameters. The math is Ah x nominal voltage, which for a 4S LFP bank would be 12.8V
Cool build! I’m sure it is far lighter than mine. I clock in at 2048Wh on mine, so it is a bit heavy to carry.
Did you make a post showing this build? I would like to see it. I am looking to build a briefcase build to keep in my car and I would like to get the max Wh I can get out of it. I feel like a crate is going to be a little awkward to deal with.
 
I got a ton of 32650 cells, and spot welded them into a 50P4s build. That’s a lot of nickel strip and spot welding…
 
ALLPOWERS 20A Solar Charger Controller Solar Panel Battery Intelligent Regulator with USB Port Display 12V/24V
Great build!
To make it better if the board behind the pwm is electrically isolated swap it with a metal plate and modify to make contact with the metal plate of the pwm with some heat sink paste to aid cooling.
Also these a common positive. You only need one + signal wire to the pwm allowing the + pv to join up with the + battery elsewhere avoiding one higher amperage connection through a not so good pwm connection point.
 
That's pretty slick. I had not even thought about a suit case build. I used a hand cart (dolly) and roll it around the house, and out to the newly designated "solar shed". Takes up a bit more room, but I don't have to carry it. After seeing your design, it looks like a happy medium would be to build one up in one of those carry cases that comes with wheels. Might be an interesting option.
 
So, I couldn't help myself. I wanted a power meter (so I added a shunt). I wanted to turn the inverter on and off without opening it (so I added the inverter switch). I wanted to solar charge it without opening it (so I added and SAE power input). Also, I wanted to plug in to 2 power outlets; 2 usb ports and 1 dc port without opening box (so I added a power strip and a dc power input). Now, the only time I have to open it is when i charge with Victron charger or power supply. All that needed the next size up in boxes. I could add another wire, but I'm just not feeling it. . . . I found a video out there on you tube showing some of these mods (of course I can't find it now to give attribution), but made a couple of my own tweaks. I think I'm done messing with this one for a while.
 

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