Azure cylindrical cells where + terminal is a cell body potential risks

[m.art.y]

Hi, so I've been using battery modules from an old Azure Ford connect van. I have so far used them in their original plastic enclosures where each cell is well isolated from another by the plastic enclosure. However I now want to remove the cells from their enclosures and stack all the cells into my battery box. Cells are cylindrical ~22 cm tall and ~5.5 cm in diameter. Both + and - terminals are at the top but + terminal is the entire cell body! All cells are sleeved but I do wonder what would happen if some sleeves get damaged somehow and aluminium bodies of the cells that are wired in series come into contact? Would nothing happen or would that be very bad? Likewise what would happen if a bare cell body which is a HV+ was to somehow touch a body of the battery box through some moisture or something? I do plan to use some wood and drill many round holes to hold the cells separated inside a battery box but let's say in a crash cell bodies were to come into contact? Just trying to think this through and would appreciate any insight that would help prevent a potential disaster .

[addvalue]

With cells in series, the first cell to make contact with a conductive casing is bad, the second cell to make contact to the same conductive casing or to the first cell is a catastrofic disaster, don't do it. But I think you knew that already. What you have there is a systemrequirement, cell to cell isolation, that cannot be designed to be failsafe and therefore needs to be designed safelife. As surely is done in the original application. If your usecase is similar, copy that, if not and more risky, don't use these cells.

[m.art.y]

With cells in series, the first cell to make contact with a conductive casing is bad, the second cell to make contact to the same conductive casing or to the first cell is a catastrofic disaster, don't do it. But I think you knew that already. What you have there is a systemrequirement, cell to cell isolation, that cannot be designed to be failsafe and therefore needs to be designed safelife. As surely is done in the original application. If your usecase is similar, copy that, if not and more risky, don't use these cells.

Thanks, to be honest it was not immediatelly obvious to me. Could you elaborate please? Are you saying that if the neighboring cell bodies were to touch in a series string that would create a short? My idea is to use some hard polystyrene foam and drill holes in it and then put cells inside those holes to isolate the cell bodies from each other. Would that work?

[mjc506]

Bare in mind this is really not all that different to the more comment -ve case....

Heatshrink is pretty good so long as handled carefully during assembly. Once the pack is together, the main risk of damage is due to vibration/fretting. Gluing the cells together guards against this (plenty of other solutions too)