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CT scans of 1k lithium-ion batteries show quality risks in inexpensive cells

lumafield.com

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Re: CT scans of 1k lithium-ion batteries show quality risks in inexpensive cells

#121

Post by CamperBob2 »

eth0up wrote: post #51
bahmboo wrote: post #50

Earlier quoted context omitted.

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.

Molicell? I have one in 21700 and it seems a great battery so far. Otherwise I'm a Panasonic guy. I ask because it sits on my forehead, inside a headlamp. Having my hands tied, addressing a problem quickly might be difficult. And them rascals get toasty fast when they ignite.

I ask because it sits on my forehead, inside a headlamp. Having my hands tied, addressing a problem quickly might be difficult

Gotta ask what kind of sport, profession, or B&D game involves wearing a headlamp while your hands are tied.

Re: CT scans of 1k lithium-ion batteries show quality risks in inexpensive cells

#122

Post by CamperBob2 »

ycui1986 wrote: post #49

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.

I wonder if ultrasound techniques might provide an alternative. If it takes 10+ hours to do a CT inspection, as someone pointed out elsewhere (if I understood correctly), then that's a lot of DSP time.

For that matter, jeez, how long does it take to just whip out a Dremel tool and take the battery apart for inspection? I must have misunderstood that comment.

Re: CT scans of 1k lithium-ion batteries show quality risks in inexpensive cells

#123

Post by jonbruner »

CamperBob2 wrote: post #122
ycui1986 wrote: post #49

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.

I wonder if ultrasound techniques might provide an alternative. If it takes 10+ hours to do a CT inspection, as someone pointed out elsewhere (if I understood correctly), then that's a lot of DSP time. For that matter, jeez, how long does it take to just whip out a Dremel tool and take the battery apart for inspection? I must have misunderstood that comment.

Scan time depends on material composition in the object you're scanning and your requirements for resolution. You can scan a dense steel object overnight to capture micron-level detail, or you can scan a plastic object in a few seconds to search for a known issue like a crack.

Battery scans are very fast; the scans in the report took less than a second. Total cycle time on a Triton CT scanner is under 5 seconds when you account for part handling.

Re: CT scans of 1k lithium-ion batteries show quality risks in inexpensive cells

#124

Post by FeepingCreature »

avar wrote: post #64
mixedbit wrote: post #60

Earlier quoted context omitted.

Unfortunately, for products with batteries in non-standard form factors, we rarely have a choice of a manufacturer. For example, with home robot vacuums, we can only hope that brands will use top quality cells, but the information what cells are used is not even available to the customer. My Neato vacuum still runs great, but now that the company is out of business, my only battery replacement options are from no-nam…

You also have the option of building your own battery pack for these, or to disassemble an existing pack and replacing the cells. How difficult that is depends on the manufacturer, but from a quick look at the Neato packs I see it looks relatively trivial.

I don't think "you should build your own battery pack" is the sort of advice that will on net reduce house fires.

Re: CT scans of 1k lithium-ion batteries show quality risks in inexpensive cells

#125

Post by bityard »

ck2 wrote: post #81

sorry for a dumb question but are old dead cells still dangerous just sitting around? I discovered an ancient powerbank the size of a deck of cards that I had not charged in many years, was blown up like a football (imagine an a sealed envelope but full of air) So that's a dead cell which shouldn't have a charge left but I guess the chemistry is releasing gas? Scared me, wrapped it in aluminum foil and put it outside…

If the cell is fully discharged, there isn't much danger because all of the energy that _would_ cause an explosion/fire is gone.

However, a LiPo cell that has entered Spicy Pillow mode (empty or not) can still theoretically burst, leaking or spraying toxic materials everywhere. So you were right to put it outside. Make sure you recycle it appropriately, so that it doesn't go into a landfill and poison the drinking water of our grandchildren someday.

Re: CT scans of 1k lithium-ion batteries show quality risks in inexpensive cells

#126

Post by esseph »

tredre3 wrote: post #112
fancyfredbot wrote: post #76

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.

Advertising works. Shocking, isn't it?

Good advertising works.

Most advertising just makes it harder on everyone else, and things more expensive.

Re: CT scans of 1k lithium-ion batteries show quality risks in inexpensive cells

#127

Post by dlenski »

> All 33 of the batteries with the [negative anode overhang] defects came from the 424 sold by low-cost brands or brands selling counterfeits. > > … > > None of the name brand OEM batteries were found to have any problems, and while there was some deviation in anode overhang for rewrap batteries, the deviations were seven times worse for the low-end cells.

Based on those stats, it sure sounds like the following is happening:

1. The reputable OEMs (Samsung, Panasonic, Murata in this study) do adequate quality control for defective batteries. The low-cost OEMs do not do adequate quality control. 2. Some portion of the defective or not-fully-tested batteries from the reputable OEMs get "diverted" to rewrappers, who essentially just relabel the batteries without doing any further testing.

Is that a correct read?

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