Abbott glucose meters under recall for catching fire.

[Helio_Centra]

The issue is if you connect them to a third party USB charger they can draw too much current and the battery overheats. Lithium cells burning is generally a bad thing. This leads me to believe that they planned on their low amperage charger limiting the current and used really cheap charging circuitry within the meter.

The recall: https://www.fda.gov/medical-devices/medical-device-recalls/abbott-recalls-readers-used-freestyle-libre-freestyle-libre-14-day-and-freestyle-libre-2-flash

Louis Rossmann ranting about it:

Teardown photos of the device: https://fccid.io/QXS-LIB01/Internal-Photos/Internal-Photos-2414553

The photos are not very high res, but you can see that the lithium cell has a protection board and a 3 wire connection with a thermistor. Maybe their charging circuitry doesn't use the temp sensor? I can't see well enough to reverse engineer it.

[Helio_Centra]

I was trying to figure out how powerful the charger they supply with it is.

All the photos of the charger I've found are blurry and low res. But the teardown photos show the text on the pouch cell says it is 1.4 Wh (which is about 380 mAh at 3.7V), and the manual says it will take 3 hours to charge it. At 380mA it would take 1 hour to charge which means the OEM charger must be more like 130mA, which is laughably low for USB.

My back of the envelope math doesn't take into account the loss from dropping 5V to 4.2V in the differences in current draw from empty to full, it is just meant to get a general idea.

[SiliconWizard]

From the very short description of the problem, it looks like they are saying that the internal charger actually doesn't limit the charging current by itself and relies on the external adapter for that.

If this is true, this is mind-blowingly stupid. I don't even get it.

[Helio_Centra]

Relying on the charger to limit the current for USB is incredibly stupid. Nobody is gonna follow their warnings to only use the OEM charger, people use whatever USB power supply is handy to charge their devices.

And this is a medical device, diabetics might need it to stay alive.

[mikeselectricstuff]

Relying on the charger to limit the current for USB is incredibly stupid. Nobody is gonna follow their warnings to only use the OEM charger, people use whatever USB power supply is handy to charge their devices.

And this is a medical device, diabetics might need it to stay alive.

And if they can't even get something as simple as USB charging right, what else have they screwed up?

[John B]

"Warranty and all liability will be void unless you use our genuine certified 50ga wire usb cables to charge the device."

[SiliconWizard]

Note that, if there was any explicit mention about that in the user's manual - and an appropriate icon next to the USB plug on the device (the one that shows you should read the manual) - then it may have been enough to pass the certification with no problem.

Of course that's still mind-blowingly short-sighted, especially if you use a standard connector in your product.

I wonder why that could even have been designed like this. Your basic few-cents Li-ion charging IC does the job fine to set the charging current to a fixed value, and does a number of other things. (Maybe they actually used one of these but set the charging current to an unreasonably high value.)
Unless it was designed by someone having no clue about how to charge a Li-ion battery and the team just added a current limit outside of the device itself as a late afterthought.

Maybe it was designed by an intern. Or they outsourced it (possible!)
Or they used ChatGPT.

[coppice]

Relying on the charger to limit the current for USB is incredibly stupid. Nobody is gonna follow their warnings to only use the OEM charger, people use whatever USB power supply is handy to charge their devices.

And this is a medical device, diabetics might need it to stay alive.

And if they can't even get something as simple as USB charging right, what else have they screwed up?

Probably nothing. People making these types of high volume low cost medical devices don't care much about reliability. There is no profit in the devices. The money is made from consumables, like test strips. What they care about is the possibility of a wrong result. If the machines frequently fail they are OK with that, as long as a machine knows it has failed and doesn't report a bogus result to the user. They go to great lengths to eliminate bad results. They put designs through extensive qualification testing for this. They do things like check the flash integrity, make a measurement, and recheck the flash. They will use MCUs with error detecting flash and RAM. When you see an MCU that has extensive integrity checking of its memory, it was probably designed for the medical device market. All focus is on never giving a wrong result, to the extent that they can get quite sloppy about other aspects of the design.

[Psi]

It feels like an outsourced design that was reviewed for safety by a committee of legal/regulatory/safety with no real engineers involved.
(Or engineers were consulted and then ignored with rational to make sure customer only uses 'their' charger)

[SiliconWizard]

It feels like an outsourced design that was reviewed for safety by a committee of legal/regulatory/safety with no real engineers involved.
(Or engineers were consulted and then ignored with rational to make sure customer only uses 'their' charger)

Yep, this sounds likely. The "ChatGPT" part I added was a joke, but we can probably add this hypothesis for real in a few years (months?) from now.

[jpanhalt]

I was remotely involved in some of those home testing developments years ago.  One, Abbott did make good equipment.  I would want to review actual documents related to this matter before judging it, but have not done so.  Two, Abbott did an interesting experiment during development (personal anecdote).

First, it included internal memory but didn't tell the test group (all diabetics) about that.  Abbott simply had that group record its data and turn it in.  Almost 100% of diabetics lied, which was not unexpected (i.e., more favorable written results than actual).

Second, it told the users there was internal memory and repeated the experiment.  Result was that a large majority still lied.

Diabetes is a complicated disease, particularly for those afflicted as juveniles.

[coppice]

Diabetes is a complicated disease, particularly for those afflicted as juveniles.

Its a massive and growing issue, so the device makers take it very seriously. Getting a design in for a blood glucose meter is a really nice win for a component maker. Increasing affluence in China and India in particular is driving a lot of new diabetes, meaning an ever growing market. Bad for health. Good for the electronics industry, especially MCUs.

[thm_w]

A good chunk of the stuff bigclive looks at is just USB -> diode -> battery. But we are talking bottom of the barrel dollar store solar lights and crap like that. I'm not convinced yet this is as simple an issue as people claim it is.
Where are you seeing that "they can draw too much current" from a third party charger? Or is that just speculation. This is what the recall says:

"Abbott is recalling the FreeStyle Libre, Libre 14 day, and Libre 2 Flash Glucose Management Systems’ reader devices, which use rechargeable lithium-ion batteries, may get extremely hot, spark, or catch on fire if not properly stored, charged, or used with its Abbott provided USB cable and power adapter. "


Some quotes from youtube comments:
" I have a gen1 reader disassembled, but haven't looked into the charging circuit so far. The "Abbott provided charger" is just a regular 5V 550mA USB power supply though with nothing special about it. "

"The Freestyle 2 has the worst battery life you can imagine. 2 days, at most. Model 1 had over 2 weeks! And yes, because you can use blood sugar test stripes with this device, getting blood in the USB port is not that unlikely. Abbott could have used a protection flap for the USB port, they didn't. "

"My Libre 2 meter for the 14 day sensor did not come with a charger. It came with a cable to plug it into a computer."

I'll see if I can find one of these locally.

[tszaboo]

It feels like an outsourced design that was reviewed for safety by a committee of legal/regulatory/safety with no real engineers involved.
(Or engineers were consulted and then ignored with rational to make sure customer only uses 'their' charger)

My rational self would say: they didn't find a charger IC with the appropriate medical rating.
My irrational self would say: they tried to find a part on ti.com's new website, got really really angry, and said f it, then we just place a resistor instead.

[coppice]

It feels like an outsourced design that was reviewed for safety by a committee of legal/regulatory/safety with no real engineers involved.
(Or engineers were consulted and then ignored with rational to make sure customer only uses 'their' charger)

My rational self would say: they didn't find a charger IC with the appropriate medical rating.
My irrational self would say: they tried to find a part on ti.com's new website, got really really angry, and said f it, then we just place a resistor instead.

They've made the medical rating requirements so onerous that a lot of semiconductor vendors have stopped trying to get their parts rated. I imagine this has severely reduced the options equipment designers have available to them.

[AlbertL]

I'll just stick with my trusty Theranos machine, thank you!

[Kasper]

The potential for overheating, spark, or fire may occur when charging the Reader with non- Abbott adapters or non-Abbott USB cables combined with misuse of the Reader and its components. Examples of misuse include exposure to liquids, damage, and introduction of foreign material into the ports

Recall says problem is from non-Abbott USB COMBINED WITH misuse.

Perhaps the charger is 'fine' but liquids in the connector cause a low current path that when combined with a sufficiently powerful charger, makes enough heat to ignite the battery.

The battery plug is fairly far from the USB connector.  I think that is mild evidence there is a charger IC between them.

[Psi]

The potential for overheating, spark, or fire may occur when charging the Reader with non- Abbott adapters or non-Abbott USB cables combined with misuse of the Reader and its components. Examples of misuse include exposure to liquids, damage, and introduction of foreign material into the ports

Recall says problem is from non-Abbott USB COMBINED WITH misuse.

Perhaps the charger is 'fine' but liquids in the connector cause a low current path that when combined with a sufficiently powerful charger, makes enough heat to ignite the battery.

The battery plug is fairly far from the USB connector.  I think that is mild evidence there is a charger IC between them.

The 'misuse' is probably leaving it on the charger for longer than it says in the manual.

[Veteran68]

Ok, so I'm a diabetic and had been on the FreeStyle Libre 14-day sensor system for a few years now before upgrading this year to the Libre 3 system. I rarely used the included scanner/test strip reader, rather I use my iPhone+app to read the CGM sensor on the back of my arm. The severity of my condition is relatively minor -- I don't take insulin, and treat my disease with meds+diet+exercise (well, occasional exercise, lol).

On the rare occasion that I have used the reader device, I don't recall ever using the included charger. I'm not even sure where it is. I have a USB micro cable routed to my nightstand from a standard 5V/1A USB port built into a power strip under the bed. We use this to charge random USB micro devices. I've used that to charge my reader overnight or at least for several hours during the day. I don't leave it (or anything) plugged in for days. I've never noticed it getting warm enough to catch my attention.

My 14 Day reader looks just like the blue Libre 2 reader in the video thumbnail posted above, except it's black instead of blue. Like this one:



The Libre 2 was an upgrade to the Libre 14 Day model that IIRC added Bluetooth alerts. When I upgraded I skipped to the latest Libre 3 which continuously communicates with my phone over BTLE so I no longer need to scan at all other than to activate a new sensor every 2 weeks. The Libre 3 does not ship with a reader as it's aimed entirely at phone+app use, however I can still use the 14 Day reader with test strips as before should I need to, so I keep it in my bag.

As to the comments about getting blood into the USB port, I have a hard time understanding how that could ever happen. To use a test strip, you prick your finger to get a tiny DROP of blood, and it wicks up into the test strip -- there is no liquid blood standing, pouring, or dripping anywhere. You'd have to be pretty intentional to get blood into the USB port, especially considering the USB port is on the side of the unit while the test strip port is at the bottom. It's not like they're close to each other. If you're bleeding THAT much during a test, you're doing it wrong and probably have a more dire emergency happening!

I believe my 14 Day reader is included in the recall, but I've not bothered to return it, because it's not plugged into a high-power charger, I've never noticed it get hot, and I rarely use it. However this has me curious enough to try it with one of my USB power meters and various chargers to see if it actually limits itself or will it pull the max current (USB micro is rated at 2A max).

I often see device manufacturers admonish you to use only their supplied charger, even if it's bog standard USB. I always interpret this to be a weak attempt at vendor lock-in, or an excuse to deny support/warranty, and not for any legitimate technical reason.

[Kasper]

However this has me curious enough to try it with one of my USB power meters and various chargers to see if it actually limits itself or will it pull the max current (USB micro is rated at 2A max).

I bet it will draw its normal charging current unless you "include exposure to liquids, damage, and introduction of foreign material into the ports"

Seems the odds of an incident are about 100 : 4,000,000.

There have been 88 incidents, including at least seven reports of fires, one injury, and no deaths involving this issue.

Devices Recalled in the U.S.: 4,210,785