Dexcom – hacked

The battery in my Dexcom G4 transmitter finally died, after a bit over a year.

Naturally, the only logical next step was to hack it open and look around — because that’s what guys like me do.

That sucker is built solid. A simple utility knife wouldn’t do the trick. 

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The serial number always made me chuckle. Nothing wrong with adult sophomoric humor. 

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I had to resort to more forceful measures to get it open. 

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Finally, it started to give way.

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Here’s a first glimpse at what’s inside. 

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This isn’t just a plastic housing around a hollow core; this thing is solid. It must be injection-molded to fill every nook and cranny inside of the thing.

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Two Maxell watch batteries. (Did you know Maxell was still around? I thought they went away with the cassette tape)

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I’ve read that some people replace the batteries in their transmitters, then close them up and they keep on going. I can’t imagine how. 

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Here’s where the batteries once lived. I suspect that big piece of copper off to the right is the antenna. 

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I tried using my trusty, rusty utility knife to lift up the battery housing, but wasn’t too successful. Bits and pieces of Dexcom flew everywhere.

Finally I separated the circuit board from the molded plastic housing. Those two circles are where the transmitter makes contact with the sensor. 

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You can see it better in these photos. 

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Those batteries, by the way, got only three stars on Amazon.

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When new, they measure 1.55 Volts.

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Used, one of the batteries measured less than a third of that (the rated 1.55 volts).

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The other was far worse. But this tells me that the batteries are placed in parallel, so the second battery extends the transmitter’s lifespan, but doesn’t offer more power. Not a typical configuration, but considering they are neither rechargeable nor replaceable, it makes sense.

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The end.

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(This entire post was written on an iPhone, because I was too lazy to copy the photos to a computer. I hope the formatting is OK — apologies if it is not)