Preparing and installing the BMS leads.

In this video I prepare and connect the BMS leads to the LifePo4 cells.
The length of 1 lead is 120cm. I'll post the wire diagram on www.easypowerwall.com (under construction)
Parts and tools to complete this step:
Cable wire stripper: s.click.aliexp...
Solder station: s.click.aliexp...
Wire for leads, 18 awg: s.click.aliexp...
Ring terminal: s.click.aliexp...
helping hand soldering: s.click.aliexp...
Drill bit 4mm to drill holes in gutter: s.click.aliexp...
Nice to have:
Silicon soldering mat (450*300):s.click.aliexp...
Cable gutter 30 by 30mm of 54 cm via your local hardware store.
Sneaky preview of all other hardware used to built the powerwall:
sites.google.c...
Franky
Easypowerwall.com

[@purpletoad352]

One of the things I saw a person do in a different video. When you bring all your leads out for the BMS, have them connected to a terminal strip that allows an extra connection. The person I was watching then used this extra terminal to hook up an active balancer that would only kick on at the higher voltages. This allowed the balancer to top off all the batteries, when almost full without wasting extra energy all the time. Also it kept the wiring clean as there wasn't a second set of wires run to each cell

[@easypowerwall]

That's actually a good idea. Today the JK BMS has an active balancer and takes kare of the little differences, but in the future I might need a balancer with higer balacing capacity. A good idea for BMS protection board V2.0

[@robjuurlink490]

I guess that video you are talking about was from Andy from the off-grid garage Australia 🙂

[@purpletoad352]

@@robjuurlink490 That sounds right, I couldn't remember which video I saw it in.

[@BradCagle]

How about use two cable gutters? Drill large holes in the bottom so they fit completely over the battery terminals, this would serve two purposes 1) clean cable routing, and 2) terminals are fully covered to prevent accidental shorts.

[@easypowerwall]

Hey Brad, that's actually a good idea. If I built a powerwall "next edition" I might consider this solution, will mention your name if the idea makes the YT movie. It might just be a challenge to drill all holes a the right position (compression cells, ...) Thanks for the feedback. Franky

[@Electronzap]

That looks good.

[@kirkdis]

I recommend to use flexible busbars.

[@easypowerwall]

Hi, That's the latest fuzz. I'm not so sure, always try to be critical and don't follow others when there are no arguments. For now I stick to the fixed busbars, like carmakers and many other professionals do... But thanks for the feedback. Frank - easypowerwall

[@kirkdis]

Hi@@easypowerwall These cell structures we are using tend to expand. Especially in those serial setups the expansion multiplies by the cells connected in a row. Andy from the off-grid garage channel recently realized about this issue. In case this happens the cells are only connected on the busbars where you will create force with solid busbars to the terminals. The flexible busbars with several copper layers and bended silouette offer enough distance to compensate a few millimeters swelling of the cells.

[@jeroendebleecker]

@@kirkdisyou’re right, but don’t forget these are already on a base tension, movement should be rather limited and certainly not getting worse since the cells width is kinda fixed anyhow

[@GapWim]

The battery connectors for your BMS leads look like crimp connectors. Is soldering them a good idea? Especially for multistranded wire (which it looks like on the video, could be wrong), I've heard several arguments that a good crimp (creating a cold weld) is much better.

[@easypowerwall]

The balancing current is max 1A, so it doesn't make a difference if it's crimped or soldered. Had same solution in previous powerwall and worked perfect for several years. Normally balancing happens rarely in a good config, so I wouldn't worry to much about it.

[@rjinhobart7748]

The cell layout is not intuitive, to a casual observer the banks look to go left to right as a front bank and rear bank, not wind around as a left bank and right bank. I would put a spacer board separating the left and right banks, taller than the cells, paint it yellow. This will serve as a physical barrier and visual reminder where the separate banks are. You've got the space in your compression setup to fit this.

[@easypowerwall]

A good idea RJ, keep this in mind if I plan a reconfig of the current setup. If done I mention your name/idea. Have a nice day. Franky www.easypowerwall.com

[@Spelter]

How do you prevent the batteries from swelling up to the side? Only with the frame? Is that enough to hold them? And what if they swell to the side, the life of the batteries will be pretty short if you let them delaminate. And you never solder wire to crimp connectors, electrical loads will destroy the solder and you will lose the connection. Just crimp them!

[@easypowerwall]

Hi Spelter. Yes batteries are compressed in the frame (see this video: kzbin.info/www/bejne/al7KZ3utfdxrZsU) The rack will hold for sure, steel is 3mm thick. Cells don't swell from the side, that's just physics. Thanks for the tip on the solder, will dig into that topic. See you soon on another movie.

[@robjuurlink490]

Do these cables need fusing? I'm not sure myself yet. They say the size of the red balance leads is thin enough to work as a fuse, but not sure what will happen when using these thicker cables.

[@easypowerwall]

Good question Rob. In my previous PW I didn't used fuses. Are anti flowback diodes needed? No. It's all about adding safety layers to your project. 1000Ah is a lot of energy....and a lot of $$, for me this little investment is all worth it. Check next video, it's about the BMS protection board. Have a nice day. Franky

[@robjuurlink490]

@@easypowerwall Yes, now I see there is a separate fuse board for the BMS wires. Great solution

[@emilyanderson3535]

I see you are not compressing them ?

[@easypowerwall]

Oh yes I do.....check video "LifePo4 battery preparation " Have a nice day. Franky www.easypowerwall.com