Sutho wrote:Well.....I bit the bullet and bought 22 x 7s3p units.
for taking "the risk" to buy this many in quantity. 22 units (462 cells) is enough to at least get some idea about DOA or obvious defective units. I suggest sending a spare unit to Doctorbass, if possible, because he will be very happy to evaluate a unit. He is an expert that can give ideas about how to salvage, harvest, & use the cells. (Of course, you might want to open a unit first to see how easy it is to do, but if you have problems Doctorbass is The Battman!
I would urge no one buy the larger sized modules until Sutho has tested these 7s3p. Why?
1) Because we really don't know yet what the percentage of "bad cells" will be in X number of modules or cells/per module. These modules have 21 cells, so buying a larger module will dramatically increase your odds of getting bad cells.
2) Starting with the smallest size module will at least be easier disassemble to take apart & see what's inside vs larger units.
3) No one knows if the BMS can be hacked & used.
4) No one knows if the cells can be "harvested" & used in some other combination. But if we can harvest the cells, then I have some cheap ideas how to charge & balance these not using a BMS. (This involves more effort & less "safety" than just using a BMS. Doable for bicycle to, perhaps, motorcycle.)
Yes, the news report states FIVE A123 customers were affected by the defect & it will cost 55 million to undo the damage. Of course, a recall is much more expensive than the actual production run, but we can probably guess there is a huge surplus of these modules that will be available for several months to come, imo, IMO.
Good Luck Sutho AND Thank You!
again for taking the 1st plunge for ES on these modules. I can't buy any of these modules until May, so I look forward to yours & others results until then.