When DIY Li-Ion battery bank goes bad !
You can watch the whole video here The key take away is "when that one battery blew, it shot a flame out 3 feet !" Those cells were some type of Lithium Cobalt Oxide (LiCoO2) cells, which ...
Forum Discussion
interesting video
probable cause "HEAT"
i NOTICED he put 100 cells in parallel ( he referred to each pack as (1) cell, (in reality each pack was a 3.7v 300amphr battery consisting of 100 cells)
then put the 'packs' in series
he also built them in series, sandwiched together
and the failed 'pack' was the center pack, no airflow no cooling,
IT got to hot, and degraded to the point of failure
Tesla batteries are built in a different configuration
a 444 cell Tesla battery is only (1) layer thick, approx 12"*12"*4"
5.2 KwHrs 233 amphrs 24v, a 6s74p configuration, IIRC is 6 in series and paralleled 74 times, (74 * 6-cell 24v)
the safest way to build , for 24v, 7 cells in series makes one small 24v battery (6 or 7 depends on which cell chemistry is being used)
then parallel multiple 7 cell batteries, to get the total ampHrs
if a cell goes bad, the fuse link for 'that series', takes all 7-cells out of the build
meaning there is never an imbalance in the number of cells in series
but the large Battery looses (1) small battery pack, instead of just one individual cell
a single flat pack 6s74p Tesla, or multiple 7-cell packs parallel
allowed for more even heat dissipation, less chance of overheating
it is 'easier' to construct a large battery, the way he did it
lots of cells in parallel, then series wire the parallel packs
it is NOT the best way, even if spaced apart to allow for heat dissipation, because if a few cells go out in a pack it still , that pack still has to pass the full amps load of the other packs, meaning each cell in the failing pack has to carry more amps, and increase cascade failure rate
probable cause "HEAT"
i NOTICED he put 100 cells in parallel ( he referred to each pack as (1) cell, (in reality each pack was a 3.7v 300amphr battery consisting of 100 cells)
then put the 'packs' in series
he also built them in series, sandwiched together
and the failed 'pack' was the center pack, no airflow no cooling,
IT got to hot, and degraded to the point of failure
Tesla batteries are built in a different configuration
a 444 cell Tesla battery is only (1) layer thick, approx 12"*12"*4"
5.2 KwHrs 233 amphrs 24v, a 6s74p configuration, IIRC is 6 in series and paralleled 74 times, (74 * 6-cell 24v)
the safest way to build , for 24v, 7 cells in series makes one small 24v battery (6 or 7 depends on which cell chemistry is being used)
then parallel multiple 7 cell batteries, to get the total ampHrs
if a cell goes bad, the fuse link for 'that series', takes all 7-cells out of the build
meaning there is never an imbalance in the number of cells in series
but the large Battery looses (1) small battery pack, instead of just one individual cell
a single flat pack 6s74p Tesla, or multiple 7-cell packs parallel
allowed for more even heat dissipation, less chance of overheating
it is 'easier' to construct a large battery, the way he did it
lots of cells in parallel, then series wire the parallel packs
it is NOT the best way, even if spaced apart to allow for heat dissipation, because if a few cells go out in a pack it still , that pack still has to pass the full amps load of the other packs, meaning each cell in the failing pack has to carry more amps, and increase cascade failure rate
