The battery builders club

I got some copper braid if you want just buy a couple feet.
That made in USA stuff from ebay, I like it a lot.

1 Like

Yeah that’s about right, limiting factor for charge is the cells then, for 4p 30Q you can technically do 12A but half would be much better

1 Like

That might work well for me, you’re probably close to me too so you wouldn’t need to ship. PM?

1 Like

Most of them have a wiring diagram on the website too, have you checked there yet? That’s how I usually double check mine.

see the dents in the fishpaper. Be careful how you fulcrum the pliers. I used flush cut snips and grab the strip perpendicular to its direction then roll it in the direction its welded down. You want to be using the cell positive terminal to leverage lifting pressure to rip the tab off, not the edges of the cell which are all negative. Thats a short waiting to happen

I just got done dismantling a pack with no fishpaper rings on the positives and this was a very tedious procedure. But youre only a mm from a 4 cell short

welds look good. Go back and remove your positives and trim the corners of the nickel strip you lay down next. That above picture the top cell has the nickel extending quite far beyond the end of the positive terminal. Another short risk. You have exactly 2.5 mm from the edge of the positive terminal to the edge of the negative terminal on a 30Q. That one looks too long

3 Likes

Alright as it relates to series connections.

The conductor’s current ratings are extremely important when choosing how you will build the battery. Copying the battery before it is a terrible idea. TERRIBLE Not only have you changed the cells, but if you want to do this safely it requires more than just owning the tool. It requires enough research to understand what the amp capabilities of the cells are, their configuration and why its that way, the current capacity of the connections and the wiring of the pack. Proper insulation, isolation and reinforcement and securing of components is super important.

I’ll be helpful, but seriously. Do some more research if you’re evaluating the current carrying capacity of the nickel you used after the pack was considered finished. Before you install this in the board, get to work on reading and take suggestions seriously.

I know very little about the black caps on the batteries. However, I would highly recommend adding fiberglass reinforced tape to the back to strengthen it more. Hot glue might be little help depending on the quality of what you used and how hot things get in the enclosure during the summer. That can put a lot of stress on the pack if there’s any flex in the deck – and there’s always a little

nickel strip… 0.15x8mm nickel strip is not suffieicent for carrying the 60 amps that pack is capable of. Actually, that pack is capable of 80 amps and many have pushed the 30Q cells to that without issues - myself included. Currently, with a single 0.15x8 across the P groups and 0.15x8 x2 series connections, your pack has an okay rating of 34 amps and a hot rating of 44.
You do not have to remove whats there. But multiple layers is a nightmare and you don’t want to be just barely covering the amp capacity. Where did you buy the 0.15x8mm from and did you salt water test it even?

Go to liionwarehouse and order some 0.2x10mm nickel strip. DO NOT go looking for 12mm strip for 18650 cells like the 30Q. The inside diameter of the negative terminal is 12.8 mm. Buy 8 or 10mm width strip of 0.2. Also, 0.25 and 0.3 are available but a litter harder to find in the states.

For a pack with a max rating of 80 amps, I would suggest 0.2x10mm nickel. 0.2x10 has a good amp rating of 28 and a hot of 37.5. I just built a 20700b 5p pack capable of the same amps with this nickel. I use the same nickel for my P groups connections too. For the series connections, I would recommend a first layer of 0.2 that covers all 8 cells. The second layer should cover 3 positive and 3 negative terminals, the third layer should cover 2 positive and 2 negative terminals. With 3 layers, you have a good rating of 84 amps and a hot rating of 112.5 amps. Always stagger the connections in a pyramid shape to help distribute the amp load.
Heres the 20700b pack i just finished. 5P for about 80 amps. Thats 0.2 x10 nickel all around
Now, my first series layer of three goes across all 5 negative cells and covers all 5 positive cells, the second covers 3/3 and the third two cells on each side. Underneath all of them, there is a layer that connects the P groups together as well. If I had skipped the P group layer and just made my first long strip a series connection, lets look at where we have a problem. The first two negative cells in the bottom left corner can output around 15-17 amps each. If there was only one layer of nickel there, the current traveling from the first two cells to the third negative cell in the pic would be 30-36 amps, exceeding the good and meeting the hot rating of 0.2x10. Dont skimp on nickel. The same concept shown here can happen where you make series connections at folds, attach wires and main leads. Always think about spreading out the load and looking for weak points

Whats the plan for the series connection between the two packs? If its spot welded, it needs to be 3 connections min. If its under 3 inches you’ll be fine with 14awg x2 as well. Insulate it well. If using wires and you don’t have a great iron, solder the wires to the nickel and then spot weld them on to the cells. regardless, have more than just the 0.15 strip where the series connection joins the cell

For the BMS, do some research here and see the examples of well laid out and routed balance leads. Keeping them out of harms way, from crossing each other unnecessarily and from being crushed and shorting is very important. As is the proper wiring. When connecting balance leads, connect them to the negative cell of the series connection is good practice. B0 is battery negative. B1 is the first P group from there. So would be connected to the positive side of the cell that the batt main negative comes from. But since you heard what I said above, were gonna place it on the adjacent negative cell which is connected to that positive via the series connection. Same goes for the remaining leads. The side of the battery is negative, the whole can is. So if a balance lead shorts on the corner of the cell it connects to, that could be bad. Attaching it to the negative cell on the series provides some protection from short there

For the positive and negative wire, 12 awg will do. Keep it under 6 inches and use an XT60H connector or Xt90.

6 Likes

18650 Keith, where I got the K-Weld from. Did not do a salt water test, he is trusted by many… But I know trust is good Control is better.

That’s where I got the cells from

The original was bridged via 4x 0.15 double layer then folded open. No nomax paper divider, I checked which was odd.

Thank you for the detailed assistance. I really appreciate it. So you would remove all stips and replace them with thicker and wider once. I will do that.
Also can you suggest the exact items from liion wholesale via links if you don’t mind the trouble. I just don’t wanna order the wrong stuff… You seem to know a lot about it.

Also the fiberglass tape and some good non rebounding tape to keep the pack tight together.

I just wanna do it right, learn about it.

Transparent Bi-Directional Filament Strapping Tape, 6.7 Mil x 2 Inch x 30yds, Fiberglass Reinforced Tape, BOMEI PACK https://www.amazon.com/dp/B07DYGTG75/ref=cm_sw_r_cp_api_i_p6h4Eb3AV3EM4

Have a good iron for the soldering needed?

You don’t need to remove the P group nickel and you could simply add to what’s there

Also, welds through increasingly thicker layers of nickel typically need more current. If you haven’t ripped off a 3m2nd, 3rd or 4th layer yet you should to see how well you’re penetrating.

1 Like

Hey guys, who seels PCBs for an 21700 (12s)4p pack in germany (or at least europe).
if i just order 12 pcs, they’re freaking expensive… :expressionless:

btw…its a long thread, sorry, if that was already mentioned…couldnt find it…

cheers!

have you looked at hummies thread?

I have tried many times and still always end up failing to see the point of individual p-group pcbs.

8 Likes

Legendary.

Ordered both. Thank you very much, far to kind.

they look cool haha

3 Likes

I really think thats all it is :man_shrugging:

4 Likes

Others have already addressed the single nickel strip for the series connections and the lack of trimming the nickel.
However your battery will fail sooner or later due to lack of flex in this area.

4 Likes

Raptor decks are pretty stiff, I can’t get mine to does a lot so maybe it’ll survive

1 Like

This is the diagram im going to use for charge only.

1 Like

Maybe. Keep in mind that this is one of the failure points on the raptor space cells

1 Like

how do these welds look?

Ok there is room for improvements (not physically though, the Battery compartment is fixed for now ). I am waiting on parts suggested by @bwahl602 atm.

The deck def. Not flexing a bit. If it would the plastic carrier would crack prob before anything.