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Safety concerns in regards to cell spacing?

recon440

New Member
Joined
Feb 22, 2022
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Excitedly I started putting together a battery case for some SCiBs: 60Ah/3p6s configuration. I have made it to such tolerances that the cells slide in comfortable and fit snugly such that there is no room to move. In fact, there is a vacuum when trying to remove the last cells in each bank.

In retrospect, I have now realized that I have omitted spacing the +/- on each parallel cluster. From a lot of the lithium builds I have seen folks just tape the cells together directly with nylon tape but now I'm worried about safety.

I have a few questions now:
  • Do the SCiBs use the the casing as a common grounding point?
    Reason I ask is that out of curiosity when I test voltage on "+" to the housing I get 1.4V and "-" to the housing I get 0.9V which gives a 2.3V potential, however when I test for continuity it reads as open which is confusing.
  • Ultimately I'm looking at redoing this and making space for a 1/8" wood shim between the +/- banks as indicated by the yellow lines as in the attached image of the current build. Would this be sufficient, or is an an additional shimming for the planar side of the cells also be required (effectively each cell being spaced exclusively)? I'm guessing this is not required as the cells are ultimately tied at the parallel junction, correct?
Thanks for any advice.

20220316_171338_v2.jpg
 
but now I'm worried about safety.
Safety? If you are using Lipo, NCM, NCA then you should be worried. If you are using LFP then as far as I know with the Aluminum cased cells the only reason for compression is to extend their life. LFP are not likely to self ignite like the other Lithium chemistries.
 
Safety? If you are using Lipo, NCM, NCA then you should be worried. If you are using LFP then as far as I know with the Aluminum cased cells the only reason for compression is to extend their life. LFP are not likely to self ignite like the other Lithium chemistries.
Sorry, I should have specified that these are LTO. My main concern is regarding the wrap between the cells being sufficient in regards to preventing a short of some kind if it were to be compromised, or if this is even a concern with the construction of such cells?
 
Sorry, I should have specified that these are LTO. My main concern is regarding the wrap between the cells being sufficient in regards to preventing a short of some kind if it were to be compromised, or if this is even a concern with the construction of such cells?
LTO batteries are safer than LiFePO4 batteries, so there should be no problem with battery compression, as long as it is not too tight. Of course, if there are any mistakes, please point them out, because I am still learning about LTO batteries.
 
I know my 280's have a + casing so I have rubber matts between them in case the shells somehow connect & they are snuggly compressed to prevent any movement of the buss bars.
 
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