16P 18S 18650 pack

[smurphy]

Hi,

For my vector/Mxus3000/midi-e bike i am at the stage of my battery build.
I want to make a pack out of 3 stacked blocks of 96 GA sanyo cells.

My questions:

1: what is the best way to make de series connections between the 3 blocks? (what awg wires and how to connect them)
2: charging coil 30Amp: inside or outside the bike?

Thanks

Steven

 

[redilast]

I would take one of those "train track" strips of nickel tabbing material, cut it in half then weld that on to the edge cells.

Then solder some 18GA or so wires from the half train track tabs to the other half train track tabs on the other cell blocks if that makes sense.

 

[smurphy]

Yes, didn't' think of it like that thanks for this.
Only problem will be that my idea was to avoid wiring on the side of the pack.

 

[redilast]

Only way I can think of to avoid wires on the side would be if you took some small tabs say 10-15mm long, soldered on a wire ahead of time, then welded it on each cell and then fed those wires through the internal gapes between the cells to the other cell block. It's do-able but would take several times as long as the other method I suggested.

 

[TristanP]

Personally I would use nickel strip to connect the blocks in series. Then I would use presspan/presspahn/isolation paper on the blocks for electrical isolation and a little bit extra rigidity. You can just glue that to your holders, by adding the appropriate glue on your holders. The last step would be folding the blocks together. You will see the nickel strip will bend perfectly and everything just looks fine. (You may want to test it before hand however, to match the length of the nickel strip and thickness of the isolation paper.)

 

[smurphy]

That's a great idea Tristan

And what is the best way to connect the main + and - wires ?
Solder a 10 awg silicon wire to the end of the strip ?

 

[redilast]

That's a great idea Tristan

And what is the best way to connect the main + and - wires ?
Solder a 10 awg silicon wire to the end of the strip ?

You do not want to soldier the wire to the end of the strip, otherwise you are requiring the single thickness of nickel to carry the current for all of the paralleled cells, which could be a disaster if you intend to pull up to say 50 Amps or so. The way I've done it in the past is the half train track method. By first soldiering the silicon wire onto the solid rail, and then welding all of the individual "planks" from the train track onto the individual cells. If you don't want the big wire hanging over the cell module you can fold all of the "planks" over so the silicon wire is directly on top of the + or - top of the cells.

+ + + + + + + + + + + + +
|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|
=================================

+ represents the + side of the cells
I represents the "planks" once you cut the train track nickel tabbing material in half
_ represents the rail of the nickel tab
= represents the silicon wire which you soldier onto the rail

Another way to do it is to put a bit of soldier between the tab on each cell and then strip the wire and run it down the line of the parallel cells. You want to do this carefully and make sure the soldier is in between the cells in order to minimize heat transfer to the cells.

 

[smurphy]

@ Redilast: exactly my concern
I tried to solder a copper bar (2mm-8MM) onto 1 side of the track, but to no success. The track is to thin and turns in all sorts of colors and shapes
Will give your method a try tonight.
Do you have pictures of this ?
Thanks for the help guys.

 

[redilast]

@ Redilast: exactly my concern
I tried to solder a copper bar (2mm-8MM) onto 1 side of the track, but to no success. The track is to thin and turns in all sorts of colors and shapes
Will give your method a try tonight.
Do you have pictures of this ?
Thanks for the help guys.

Here is a picture of a smaller 25.6v pack I made.

I first soldered the 8GA wire to tabs then I welded them on for the + and - connection.

 

[smurphy]

Nice job Redilast. Thanks for sharing.

 

[BeachRider2016]

Hi,

For my vector/Mxus3000/midi-e bike i am at the stage of my battery build.
I want to make a pack out of 3 stacked blocks of 96 GA sanyo cells.

My questions:

1: what is the best way to make de series connections between the 3 blocks? (what awg wires and how to connect them)
2: charging coil 30Amp: inside or outside the bike?

Thanks

Steven

Beautiful packs. I have a question though as why you choose 18s over 20s ?

On my current build, im debating the question on 18s or 20s.
20s bms are readily available, 18s not so much.
As for the frame, 18s fits better, 20s too long and cover up the holes on the bottom of frame.
I still havent decided which one to go with.

 

[999zip999]

16p you can go without bms with monitoring. You know daily monitoring to you figure it out.

 

[spinningmagnets]

For series connections, consider this https://www.etsy.com/listing/231678857/copper-flat-bar-stock-375-in-x-36-x

$0.05 per centimeter of length ($0.60 per foot?), 1/32th thick (0.032-inch/0.8mm), times 0.375 -inch wide (9.5mm) equal in cross section to 8.5-ga solid copper wire. Use several strips between paralleled groups, and then after bonding, coat with insulating goo to avoid oxidation...

 

[smurphy]

@ BeachRider2016:
18S is max i can fit in the vector frame for my 16P configuration.
For me range is more important then speed.
I use the Adappto BMS.

Thanks for the link Spinningmagnets.

 

[BeachRider2016]

I think your frame is pretty similar to mine. But I decided to go with 20S. I will have to stack 3 cells on top of each other like in a laptop pack.