Do I need cell spacers for a 72v battery pulling 85 amps?

[r0b3rz]

Hello.
I am building a 20S3P Samsung 40T battery for a CYC X1 Pro Gen 4. The space is very limited and impossible to use regular spacers.
In the past I have glue directly cells but with less discharge rate...

What do you think about this?

I found a similar thread but without much info about it.

Here a pic of a test of the box: (blue brick is the size of BMS)

Thanks in advance.

 

[thebes]

You should ideally be using cell holders for a pack of any size unless there is a better solution to keep the cells separated from each other as if they werent vibration will eventually wear through the shrink wrap resulting in a possible short between cells/groups. You could minimize this by separating each cell with fishpaper or some other similar insulator but its still preferable to use cell holders.

In your image there is more than plenty space for cell holders, it should be fairly easy to whip something up in cad with 0.5-1.5mm spacing between the cells and print it. If you dont have a printer there are services that will print and ship you the parts or you could pick up a used printer for fairly cheap.

Heres an example from a pack Im working on for my stealth bomber clone,

^^This is just a test fit, nothing permanently in place yet hence why it looks a bit, uneven...lol...
Here are some other random test prints

 

[docw009]

THe hex cell holders that snap together take up lots of space. Maybe a printed holder can be made more compact.

 

[chuyskywalker]

If you really, really, really can't afford the cell spacers, an acceptable option is to glue the parallel groups together, then add some fish paper between each of the parallel groups. There's basically no way a pack will rub through the fish paper to make a short, and any cell shell contact within a parallel group is, well, effectively the same as the parallel nickel strips purpose.

 

[r0b3rz]

If you really, really, really can't afford the cell spacers, an acceptable option is to glue the parallel groups together, then add some fish paper between each of the parallel groups. There's basically no way a pack will rub through the fish paper to make a short, and any cell shell contact within a parallel group is, well, effectively the same as the parallel nickel strips purpose.

THe hex cell holders that snap together take up lots of space. Maybe a printed holder can be made more compact.

You should ideally be using cell holders for a pack of any size unless there is a better solution to keep the cells separated from each other as if they werent vibration will eventually wear through the shrink wrap resulting in a possible short between cells/groups. You could minimize this by separating each cell with fishpaper or some other similar insulator but its still preferable to use cell holders.

In your image there is more than plenty space for cell holders, it should be fairly easy to whip something up in cad with 0.5-1.5mm spacing between the cells and print it. If you dont have a printer there are services that will print and ship you the parts or you could pick up a used printer for fairly cheap.

Heres an example from a pack Im working on for my stealth bomber clone,
View attachment 358899
^^This is just a test fit, nothing permanently in place yet hence why it looks a bit, uneven...lol...
Here are some other random test prints
View attachment 358900

Thank you, guys.

I am going to try to fit a thin holder like you did thebes. Looks very nice. If not, the second option: Isolate groups.

This is my first high discharge battery and I don't want to burn my bike and me


I will let you know what I can do.