111–120 of 127 posts
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My understanding is that material composition can make a CT scan take a really long time. It makes sense to me that scanning a battery would be pretty slow, given what they're made out of.
I just assumed it would be impractical due to physical changes of the object from multi-hour exposure to X-ray energy.
I'm not sure who is in charge of advertising at lumafield but in the last few weeks I've seen James Hoffman use lumafield CR scans on coffee pucks, Jeff Geerling use them on a Pi 500+, and now this. I'm probably not their target market but I definitely know who they are now.
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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…
Can't recommend charging cells that have fallen below their official stop voltage- the liability and risk is too high. However, numerous papers have shown that the serious risks happen if they're reverse charged. I wouldn't use anything but a bench supply stuck outside though.
I did have a failure once and it was on a new molicel. I damaged the outside wrap of a cell while building a pack and it had a short and self-discharged the cell, likely reverse charging it in use. A week or so later the charger rejected it. When I pulled it out it was a fully shorted cell that would accept no charge, but it did not catch fire.
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…
It's a long video but one takeaway is to only use cells from the top manufacturers: Samsung, Panasonic, LG and Sony. They are amazingly safe.
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Thanks! For whatever reason the battery datasheets I've been looking at this week called it IR. I'll definitely be including it in the next cell tester I build.
IR = Infrared? R = symbol of resistance i = internal https://en.wikipedia.org/wiki/Internal_resistance So Rint is also used. The proper way would be with a subscript but I don't know how to do that.
The conclusion I drew from this is that if real capacity is much less than advertised the battery is best avoided.
What about expensive cells? Any quality risks in them or they are perfect?
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IR = Infrared? R = symbol of resistance i = internal https://en.wikipedia.org/wiki/Internal_resistance So Rint is also used. The proper way would be with a subscript but I don't know how to do that.
There's a Compose key binding for it in https://github.com/kragen/xcompose/blob/master/dotXCompose . Usually a lowercase i is the small-signal current, but some ambiguity is probably unavoidable with short abbreviations.
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There's a Compose key binding for it in https://github.com/kragen/xcompose/blob/master/dotXCompose . Usually a lowercase i is the small-signal current, but some ambiguity is probably unavoidable with short abbreviations.
That's an interesting thing you've got there. If this were standardized I might actually take the time to learn some of them. My own language has a whole pile of diacritical marks that I never use, I just transliterate everything to ASCII and call it a day. This obviously is very broken but what with every editor and every OS having their own way of doing super/subscript and various composition method it never seemed…
problem with Lumafield is their pricing. Last time I checked with them. They don't sell the CT machine. It was a lease/subscription at yearly cost of $75,000. It was not justified for what we are doing.