What would you recommend in this case? I would say that if a battery pack fails, disassemble it immediately to harvest good cells before the BMS kills them
I might be overreacting. I once have a very old laptop running on Windows XP, in 2004 IIRC the battery pack failed so I removed them. and in 2018 I disassembled it and all the cells are all 2.4V. They are still reusable as I looked up the official datasheet and I measured that it still have 2000~2100mAh (new cells are 2400mAh) after years of storing at 2.4V. It might be the “suicide fuse” triggerd to physically disconnect them, there’s no way to maintain 2.4V as there’s parasitic drain of the BMS
There’s no upper limit of the level of shadiness. They can get away with most of the anti-comsumer practice as long as they use “safety” or “security” as an excuse. What if they disable and destroy cells after warranty expires when the battery are degraded to 70% as end-of-life despite the user still want to continue using them, and all cells are still in good condition and then they claim that “its for your own safety to discharge degraded battery”
You may be overestimating the parasitic drain of the bms, unless they get confused they draw very little power. I just pulled up a random datasheet from a laptop battery controller from 2007 and that had 8uA low power storage drain, that would take almost 30 years to drain a 2100mah cell. I’d hope they got more efficient since.
Yep all the way down to pretty much 0. The bms does not necessarily need to be working for that, it could well be that the bmd has to be working for that to not happen. Great as a safety feature, not great for harvesting.
Except this one isn’t just made up, noone wants to be the next note 7.
That would be evil but there is no evidence of that being the case here. The pile of batteries I pulled apart had some that were still alive that were extremely degraded (like 2900mah cells that still held about 600mah).
Well, I’m not lying, the batteries are indeed 2.4V after more than a decade of storage in “failed” condition. I’m confused as well. Maybe older batteries and BMSes are better constructed? I heared that some modren laptops cut costs so much that they won’t boot without a battery even with AC adapter connected.
Given it’s take 30 years for the bms to discharge a single cell from it’s own drain that isn’t too surprising. It just doesn’t have the full discharge.
It also means that a “dead” battery without the full discharge feature is still dangerous if impropperly disposed of 10 years later.
That makes sense, IIRC when the note 7 battery explosion is exposed Samsung pushed an “update” to “instruct” the smartphone to ban charging before battery replacement was made.
I guess my anecdotal finding doesn’t apply to all instances at all, I bought and used numerous power banks, all of them has their BMS broke first before battery degradation except one, so now I have a dozen of battery cells that idk where to put XD. It they all “suicide” as the bms fails → the bms doesn’t know the battery health → the bms assume the cells are failed → the cells get discharged to 0.00V and killed, I would have zero battery cells to harvest.
This indeed has caused losses. When I was working at an electronics company a device failed due to a critical battery pack has degraded. To make things weireder, the battery would descharge 100mAh once, but if you left it alone it’ll rebound to 4.1V, discharge 100mAh again, it’ll rebound to 4.05V and so on, if you discharge it very slowly it’ll draw 2600mAh(2900mAh battery cells) so my coworkers assumed that the battery degradation isn’t that severe as 90% were low wattage usage