18650 vent at positive end of cell

Joined
Apr 17, 2022
Messages
31
Hello, I am building (almost built) a battery pack (14s4p). I am using magnets to hold the nickel strips. To cut a long story short, how much of that "vent" can be covered up? I've seen battery packs have tape wrapped all around the battery and/or pack which looks like it has very little air flow.

On my pack I've got the usual 18650 battery spacer/holders that the batteries sit in, 8mm nickel strips (doubled up actually, 0.3mm thick), and 12mm (x 3mm) magnets to hold the connections in place. The nickel strips look like they cover the whole vent and then the magnet on top doesn't look like there is much air that can get in or out of there. The strips are flat obviously so there's still a bit of air that can get in and out but yeah I can't find any info about what' acceptable in how much to cover and what not.

They will then be sandwiched together. Again now really sure how much pressure I can apply to this sandwich. The batteries don't expand in any way do they? Am hoping to have it tight enough so as to not cause any connection issues.

I know there are people against this type of build. I did go down the spot weld route but decided against it in the end. I will take precautions to make sure connections/magnets are in place. This part I'm not worried about.
 
Just so we understand correctly (picture would help) - you are not welding or soldering your inter-battery connections at all? Just connecting with magnets? Woa! That's not going to end well. Ebike batteries get thrashed around pretty well and will probably shift your magnets and the high current loads demand a welded or soldered connection. A shifted magnet can result in a direct short and that never ends well with lithium batteries. You're playing with fire or worse.

In normal use an 18650 cell will not vent or swell. If/when they do they are trash.
 
Ok cool, that's good (about the venting).

I've weighed up the pros and cons of this setup and have not taken it lightly. The whole pack will be pretty tight. There will be hardly any vibration at all. It's for a (kids) quad bike which (he) will be going pretty slow. Once the magnets are all compressed with poron foam there will be zero movement, so all good.
 
Back
Top