41–50 of 127 posts
I just got a new tenant in my rental house and this time I had to add a clause to the lease enumerating brands of lithium-ion batteries the tenant is allowed to keep on the premises. These things are basically grenades that you can buy for $2 on Temu. Stronger regulations needed.
I find their table of advertised vs actual capacity to be misleadingly negative. They only discharged to 3v. 2.7 could be viewed as more standard. 2.5 is not unheard of. For example, the vapvell 4000 they said was around 3000. They even have a note that says that isn't a reasonable capacity estimate. And yet they still put the percentage and the number. As if they've falsely advertised. However, if you go to vapcell'…
How do you even drain a 3.7V lithium ion battery below 3.3V? My devices that use 18650s will not let them go below that. Is it 3.3V nominal and the actual voltage is lower, like how they’re 4.2V fully charged?
The remaining 10-20% is above 3.8 and below 3.70v. 4.2v is the max to ever intentionally apply to a cell, and 2.5v is the minimum anybody specs as end of discharge.
As such- the "nominal" voltage is 3.7v or 3.8v.
Possibilities for 3.3v cut off include: LEDs' combined forward Voltage, a BMS set to that voltage, high drain applications pulling the voltage below a lower (potentially much lower at 10C to 50C discharge) cutoff voltage.
These are, of course, for NMC lithium secondary/lithium ion cells. NOT LiFePO4/LFP/LTO/Na-ion.
Theres lots of FUD, but most lithium stories are Li-Po cells (cell phones, RAdio-Control, laptops). Of the Li-Po's- most of them are for RC usage without any inbuilt protection.
LiPo's are beat treated like they're ziplock baggies full of 100mL of gasoline. If you handle them, I suggest buying an Ash Pot- their double walls give you a chance of containing a flaming pack. Best to just do it outside though.
Earlier quoted context omitted.
How do you even drain a 3.7V lithium ion battery below 3.3V? My devices that use 18650s will not let them go below that. Is it 3.3V nominal and the actual voltage is lower, like how they’re 4.2V fully charged?
I guess leave them sitting in a laptop in a barn for a few years. I was given some old shit gateway the other day, tried to charge it, no dice. Ripped the pack apart to find samsung 18650's with approx 0.7V voltage. Against ALL recommendations I put these cells into a MC3000 and they charged up just fine to 4.2V. It does a 0.15A charge per cell until it gets above 3V. Then I had it set to 1.92A bulk charge. Fire exti…
I wouldn't use anything but a bench supply stuck outside though.
Earlier quoted context omitted.
It does help. It raise the opportunity to discuss it, which is helpful because not everyone is aware that this is a problem, and like many other lease clauses it is there to assign blame in case an exceptionally bad event comes to pass.
like many other lease clauses it is there to assign blame in case an exceptionally bad event comes to pass That sounds like a job for the insurance company. You do have insurance, right? Did they have any input on this clause?
After we monitored many battery fires, we decided to build a casing which can sustain lithium fires for typical e-bike batteries: https://www.youtube.com/watch?v=v0NXXfCA2CY
That's a great idea. Are you making a product or sharing the build?
(no affiliation)
I just got a new tenant in my rental house and this time I had to add a clause to the lease enumerating brands of lithium-ion batteries the tenant is allowed to keep on the premises. These things are basically grenades that you can buy for $2 on Temu. Stronger regulations needed.
How is any tenant possibly supposed to comply with that? Rip every piece of electronics they buy apart to check?
Earlier quoted context omitted.
like many other lease clauses it is there to assign blame in case an exceptionally bad event comes to pass That sounds like a job for the insurance company. You do have insurance, right? Did they have any input on this clause?
They dictated it.
The conclusion I drew from this is that if real capacity is much less than advertised the battery is best avoided.
Seems like a good time to highlight this video from Grin Technologies and their experience with ebikes over the years. https://www.youtube.com/watch?v=j92Gt4VviSQ Summary Statement: He summarizes the results of the "sabotaging" attempts by saying, "we just couldn't for the life of ourselves get a nonprotected modern lithium battery to do anything" [02:40:27], in terms of causing a fire. (referring to 18650s) There ar…