Tuesday, June 9, 2015

Batteries, greed, ingenuity and ...

I am not going away just yet

Thanks to those of you who asked why this blog slowed down. I really do appreciate knowing some of my readers care. Some difficult circumstances have limited the time I could devote to the blog. Don't worry - if you care at all - I am not shutting it down. I currently have a few projects going on, including attempting to get a non-AP Dexcom to work at a level close to a well performing Libre sensor, running different prediction algorithms retrospectively on 18 months of my son's data, the question of dosing or not dosing based on CGM data and, a possible final Libre summary. I've also been a bit busy with the ton of side issues every caregiver for a difficult teen unfortunately knows too well. Diabetes sucks at so many levels, direct and indirect, that even if you get good results, one just feels like being stuck in an endless dark tunnel.

But today I feel like commenting a bit on a "cool hack".

Batteries and greed...


Dexcom, a company that offers very good products and an excellent customer service, isn't beyond milking its customers for the benefit of its main shareholders. Well, that is capitalism and that - we are told - drives innovation...

The area where Dexcom's greed is probably the most obvious is in what I would call the "transmitter tax". The Dexcom transmitter that you clip on your sensor needs electricity to power the sensing and process the data it collects. That electricity comes from two small watch batteries embedded in the transmitter. So far, so good.

But of course, the batteries aren't user replaceable and you have to buy a new transmitter when they run out of juice. It is not totally unreasonable since an IP68 design with user replaceable batteries could be slightly bulkier. There is also the risk that a kid could swallow a loose battery. Swallowed batteries are ugly. Still, Chinese manufacturers manage to include batteries in their cheap toys and comply with regulations. So why not Dexcom? But I digress...

The answer is, in part, because Dexcom charges a ton of money for a transmitter. The clearest indicator that greed plays a major role in that situation is that the price varies a lot from buyer to buyer. The replacement transmitter, functionally equivalent to a watch battery swap, can cost anything from $330 to $900 depending of the buying party.

Fun fact: two batteries weigh 1.5 grs. Assuming you pay $700 for your replacement transmitter, you are paying those batteries

  • 12 times their price in pure gold.
  • 7.4 times their price in pure platinum.
  • 0.000017 times the price of Californium 252
Yeah, I just wanted to be positive with the last item. It can always be worse.

Batteries and ingenuity...

That great battery robbery hasn't remained unnoticed and has attracted the diabetic community hacker's attention. User Joern (joern's post) went as far as taking x-rays of the transmitter to devise an ingenious battery replacement strategy. Extremely impressive in terms of DIY project. I did enjoy the progress reports last year. And, since last week, this evolution has been doing the rounds. A dremel, a few tools will save you anything from $308 to $898 if you can tolerate a Frankentransmitter. Ain't that great?

Batteries and...

The hack isn't easy: people have tried removing the batteries and ended up shorting the transmitter. But ingenuity came to the rescue again! If one could not remove the batteries, why not use their sides as contacts? What a great idea! Time consuming because the batteries are effectively armored, but so cool. But wait a minute - why are batteries effectively armored? Could there be a reason? As a matter of fact, there is...


The content of batteries is typically highly toxic.


That's the reason why you are asked to dispose of your batteries properly and why most industrialized countries offer secure recycling services. To be honest, it used to be a lot worse than it is now. A recent watch battery "only" contains silver and zinc. Just a few years ago, it used to contain mercury (see Renata's advertisement), a metal whose terrible toxicity has been established. You may have heard of the Minamata disaster. Or maybe, since we are talking about hackers, you may have read the story of that electronics inclined hacker or even that would-be hacker-murderer?

Did any hacker check the type of battery in the Dexcom's transmitter? Maybe they did. Maybe not. While watch batteries containing mercury are definitely on their way out in the EU and most US states, "silver oxide" batteries have a shelf life of around 5 years. Mercury free silver oxide batteries, first announced as a major breakthroough in 2005, started taking a big share of the market in 2010 - 2011. But batteries containing mercury batteries can still be found... Has Dexcom stated their products were 100% mercury free? Even if Dexcom's intention is to deliver mercury free products, do they check what their supplier provides? Hard to be sure. Especially since they don't seem to have a very strict quality control process on their current receiver and batteries...

That means that, in the worst case scenario, by reducing a battery to dust with a Dremel and a diamond disk, you are filling your house, lab or shed with mercury tainted toxic dust...

In the best case scenario, it is only silver and zinc. Not a big deal. Or is it?


Let's try to see the balance of the whole process.

On the financial side we have the following condition to satisfy

amount saved > tools purchased + hours of work * hourly rate

That one might be easy, depending on what your job is and the tools you already own.

On the health side we have the following condition to satisfy

health cost * ( HbA1c on meter - HbA1c on Dexcom) * one patient 
((health cost inhaled mercury * 0.1) + (health cost inhaled zinc * 1)) * size of family


In other words, running your Dexcom instead of using a BG Meter has a potential health benefit linked to the reduction of your HbA1c. Is that benefit bigger than the health cost associated with the contamination of your home and your family lungs to zinc dust (100% certain) or mercury dust (let's say there is a 10% probability)?

I don't know how to resolve that inequality, and I don't think hackers pulverizing batteries do either.

But that is a question worth asking if one values rational decisions.

And it is worrying it wasn't even asked.

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