My Portable Battery Box

Announcement - Help us fight the BOTS! Please report all spam including stuff in your inbox!

Cypher618

Member
Joined
Jan 14, 2021
Messages
34
I have been working on my first battery project beyond the small power packs with a couple cells.

When I started I knew I wanted to put it all in some kind of plastic storage container. I looked around and found this keeter tool chest and knew it would be an insanely cool container for this project because the top is split in halves on drawer slides.

I'm going for modularity and standardization on the battery packs. 7s10p packs with the cheap 20A 7s common port bms's you find all over the place. I have a 1500watt pure sine inverter so to comfortably run it at full power I need 4 of my standard packs, but my container can fit 8 of these packs. If I only want to run the lower voltage items I only need one pack.

On the left hand sliding half I modified the inverter to fit and moved its displays and start switch onto the face of the container. On the right hand sliding half I'm building the controls and lower DC voltage outputs. 12v automotive, 2x usb qc 3.0 charging ports, a current/power/voltage display for the 100A shunt in line with the batteries, and eventually an arduino with a touch screen to control some custom charging functions based on maybe a modified boost converter with variable current output (if I can get that to work this part is TBD).

In the bottom I put the batteries using some 8020 extrusion to secure the batteries in sets of two and mounting the power bus to the top of the 8020 rail. I will also build in a charger to target around 700W peak charge power. 120V receptacle is mounted on the rear face of the box between the wheels. Also some cooling fans eventually...

Batteries are all recovered from modem batteries. Battery cables are #6awg DLO cable which I got for 1.13/ft USD. I know silicone is better to work with but its too expensive. In my view if it gets hot enough to need the 200C temp rating of the silicone wire I have done something wrong!

Lots of TBD, since I just kind of stare at it for a while to figure out what I want to do next, but its coming together!
 

Attachments

  • 20210219_170902.jpg
    20210219_170902.jpg
    3.9 MB · Views: 183
  • 20210219_170936.jpg
    20210219_170936.jpg
    1.7 MB · Views: 179
  • 20210219_170923.jpg
    20210219_170923.jpg
    3.9 MB · Views: 189

OffGridInTheCity

Active member
Joined
Dec 15, 2018
Messages
1,738
> I just kind of stare at it for a while to figure out what I want to do next,
Funny you say that. I do that as well - I tell my wife "I'm going to stare at the X for a bit" - and then figure out the next step... or not if it's just not clear yet :)
 

Bubba

Member
Joined
May 9, 2018
Messages
300
I have been working on my first battery project beyond the small power packs with a couple cells.

When I started I knew I wanted to put it all in some kind of plastic storage container. I looked around and found this keeter tool chest and knew it would be an insanely cool container for this project because the top is split in halves on drawer slides.

I'm going for modularity and standardization on the battery packs. 7s10p packs with the cheap 20A 7s common port bms's you find all over the place. I have a 1500watt pure sine inverter so to comfortably run it at full power I need 4 of my standard packs, but my container can fit 8 of these packs. If I only want to run the lower voltage items I only need one pack.

On the left hand sliding half I modified the inverter to fit and moved its displays and start switch onto the face of the container. On the right hand sliding half I'm building the controls and lower DC voltage outputs. 12v automotive, 2x usb qc 3.0 charging ports, a current/power/voltage display for the 100A shunt in line with the batteries, and eventually an arduino with a touch screen to control some custom charging functions based on maybe a modified boost converter with variable current output (if I can get that to work this part is TBD).

In the bottom I put the batteries using some 8020 extrusion to secure the batteries in sets of two and mounting the power bus to the top of the 8020 rail. I will also build in a charger to target around 700W peak charge power. 120V receptacle is mounted on the rear face of the box between the wheels. Also some cooling fans eventually...

Batteries are all recovered from modem batteries. Battery cables are #6awg DLO cable which I got for 1.13/ft USD. I know silicone is better to work with but its too expensive. In my view if it gets hot enough to need the 200C temp rating of the silicone wire I have done something wrong!

Lots of TBD, since I just kind of stare at it for a while to figure out what I want to do next, but its coming together!
Nice idea. Great for camping. If the balance leads are long enough, have you thought of moving the BMS and placing some sort of insulation around it so temperature from the cells or inverter don't impact it's function. (cheap bms after all)

I just learned about QC3.0 for my sons Wireless HTC Vive headset. Good choice. Your 6awg Diesel Locomotive cable is rated more than enough for your packs.

Question: What fuses are you using on the 10awg wires from each of the packs?
 

Cypher618

Member
Joined
Jan 14, 2021
Messages
34
Under load test from full capacity to empty the BMS is actually the part that gets the warmest and its still not too hot. Under the designed load I'm only running around 46% of the C rating. The batteries just get a little warm. I'll have to check it with the heat gun next time but its very reasonable.

The inverter barely puts out any heat at 800W, we'll see what happens when I get it up to full load. Its a smart setup when unloaded it wont even run the fans so the idle load of the inverter is only 6W. Either way I have some pretty serious cooling fans I can put in the case... like the kind of fans that spin so fast you can feel the gyroscopic force (from asic miners).

At full C rating the packs should be good for 32amps. The fuses are 40amp right now, but that's mostly just because those are the fuses that came with the holders. Good enough for now. I do still need a master system fuse though.
 

Cypher618

Member
Joined
Jan 14, 2021
Messages
34
I know it has been quite a while but I did finish this project!

Ended up with just under 4kwh capacity for my portable bank. I'm able to charge at 500W with a built in power supply which also means this can function as an active UPS for 500W, which is about what I get from the charging supply.

I also added a master system breaker at 100A.
 

Attachments

  • 20210417_133809.jpg
    20210417_133809.jpg
    4.4 MB · Views: 79
  • 20210417_153839.jpg
    20210417_153839.jpg
    4.1 MB · Views: 78
  • 20210417_153843.jpg
    20210417_153843.jpg
    4.3 MB · Views: 71
  • 20210417_153848.jpg
    20210417_153848.jpg
    4.1 MB · Views: 66
  • 20210425_175033.jpg
    20210425_175033.jpg
    4.9 MB · Views: 64
  • 20210425_175037.jpg
    20210425_175037.jpg
    4.6 MB · Views: 58
  • 20210425_175042.jpg
    20210425_175042.jpg
    4.8 MB · Views: 56
  • 20210425_175049.jpg
    20210425_175049.jpg
    4.5 MB · Views: 52
  • 20210426_214031.jpg
    20210426_214031.jpg
    2.6 MB · Views: 49
  • 20210501_144532.jpg
    20210501_144532.jpg
    4.7 MB · Views: 46
  • 20210515_101807.jpg
    20210515_101807.jpg
    4.1 MB · Views: 83

OffGridInTheCity

Active member
Joined
Dec 15, 2018
Messages
1,738
Wow - thank you for sharing.
Look like 4 x 7s10p - estimating 2kwh+ battery in the box?
Very nice looking result - I love the slide-out trays of the box!
 

italianuser

Member
Joined
Feb 25, 2020
Messages
358
Looks real awesome! Congrats! :giggle:

A nice neat job. You just reminded me of buying the fuses for the batteries. I saw the ones you bought but they lack the CE marking, that's why I didn't buy them... must search for them again.
 

Cypher618

Member
Joined
Jan 14, 2021
Messages
34
It has 8 x 7s10P packs and I got just around 3.8kwh, one of the pictures shows the power meter after load test. The box is a keeter tool chest. It was perfect for this project.

It terms of CE fyi that doesn't really mean much for electrical safety and its also self declared. So unscrupulous manufacturers can just stamp it on regardless and who is going to go find them in China to do anything about it. Amazon does not care about making sure equipment is approved, AliExpress certainly doesn't either.

An electrical inspector isn't looking for CE, they are looking for cUL, CSA, TUV, etc. Also when it comes to lower voltage the inspector has some discretion on what to pass. In Ontario anyway where our regulator is pretty stringent.

So regardless of markings its best to do your own testing when your source is suspect. Marks can always be counterfeited.

Source: Am licensed electrical engineer regularly working with electrical regulators on equipment approvals.
 

cak

Member
Joined
Mar 14, 2021
Messages
64
I really like your design and seams like a nice balance of compact and portable but lots of power.
 

NCislander

New member
Joined
Aug 19, 2021
Messages
3
I know it has been quite a while but I did finish this project!

Ended up with just under 4kwh capacity for my portable bank. I'm able to charge at 500W with a built in power supply which also means this can function as an active UPS for 500W, which is about what I get from the charging supply.

I also added a master system breaker at 100A.
New to the forums, thanks for more inspiring photos of your 7S10P banks. Nice the way you integrate them into a portable power unit.
Once I scavenge/collect/buy enough cells I want to build something similar for my 1st battery bank project. Pre-PowerWall project.
Thanks for sharing yours out here.
 

Cypher618

Member
Joined
Jan 14, 2021
Messages
34
I don't know where you are located but for Canada anyway I have found if you want to get moving and don't mind paying a bit battery hookup is a good option.

Still much cheaper than new all things considered (shipping, duties).

I rent so a home Powerwall really isn't in the cards yet!
 
Top