Planned Obsolescence?

Spending $1,000+ annually on top of the huge cost of sensors really seems excessive…Does anyone know why the receivers are only warrantied for a year, and rarely last much longer than that? Is it just batteries starting to fail in the transmitter or receiver? Or something else mechanically that fails? Pumps seem more complex than the receivers, and they seem to last 4 years or more…

I’m pretty sure it has to do with the batteries. There’s not much suggesting it won’t go longer than that. Even MM has a similar warranty on their transmitter.

On the flip side though, if your insurance covers it, they could pay for the cost of a replacement after a year if it stopped working.

Thanks for posting. This is a topic I’m interested in. Sorry, I have no answers for you, but will be following to see what replies are posted.

I actually think it’s the transmitter that tends to fail after one year (although most people report much longer use). Since the transmitter isn’t recharged (unlike the MM transmitter, which is charged every 3rd cycle), I would guess that its shelf-life is fairly limited.

The receiver might have battery issues (memory from repeated recharging?), but I think it probably lasts as long as a pump.

Thanks, all. Would be nice if they allowed the battery to be replaced in receivers and/or allowed the transmitters to be recharged. I’d be willing to pay significantly more (my insurance only pays half) if it would last for more than a year…

Now I’m wondering if there’s a way to recharge the receiver so that it lasts as long as possible. (Recharge before it’s all the way drained, maybe?) Even if there’s no way to extend the life of the transmitter, replacing one piece is still less expensive than having to replace both components.

Hi Rita…Yup, my insurance (Aetna) will pay 50%, but that still means $570 out of pocket for the transmitter and receiver, plus $140 a month for sensors. It really does add up, especially since we need to save tens of thousands (we’re trying to adopt a baby, and need to replace our roof…all mega-expenses.)

I was doing pretty well without them, last A1C 5.8, so I need to figure out whether the benefits are worth the actual cost. (Although now I’ve started on Dex, it would definitely be hard to live without it. Amazing how quickly I’ve come to appreciate the information it’s giving me.)

Thanks so much, Rick. This is good to know! I’d been letting the receiver run down until it got to one blinking bar, but I’ll definitely start recharging when it’s at two bars…Guess that’ll mean recharging almost every day, but it’ll be worth it if I can make the receiver last longer.

Are you saying we also shouldn’t let it charge up all the way? (I’ll charge for about 70 minutes, like you said, but it would certainly be easier to just be able to leave it for 2-3 hours, without actually timing it.)

As for your last point, yes, this is what I’m a bit upset about, that Dexcom is using unreplaceable batteries. I understand why there’s no way to replace them in the transmitter, since it needs to be water-tight, but not allowing replacement in the receiver really DOES sound like planned obsolescence…

Shannon, I’ll use a “Reply” to talk about the Transmitter. (I made a separate, really big post about the Receiver’s battery; it’s shown below.)

Oddly, the lifespan of the Dexcom Transmitter (not rechargeable) seems to exceed the lifespan of the MiniLink! Apparently, all the hassles of recharging (required with every second Sensor Start/Restart) buys nothing in overall lifespan. Minilink is also very costly to replace, in comparison’s to Dexcom’s Transmitter. Dexcom wins any sort of Transmitter “throw down” comparison; it’s vastly better all around. There’s a lot of MM users posting on forums and chat boards about their MiniLinks dying young, and they’re often very angry.

The Dex Transmitter battery is definitely built with a Lithium battery. But it’s not a Lithium-Ion rechargeable; the Chemistry and construction in use-only once Lithium batteries allows then to store MUCH more energy per gram, and MUCH more energy per unit volume, than the rechargeables. That’s the main reason why Dexcom’s Transmitter lifespan beats Minilink.

There’s many different kinds of use-once Lithium batteries, with different chemicals used in the way they’re built. They might be using a fairly “normal” one, with an energy density 2-3x as good as the best Lithium-Ion batteries. But they might be using a very special battery, for example, one made from Lithium Thionyl Chloride. (That’s the kind they use in outer space, where stored-energy-per-gram REALLY matters because it’s so costly to lift each gram of “extra” weight into orbit.) These batteres can have 4-5 times the energy density of rechargeables. But they are a class-9 hazardous material, so you won’t find them at “normal” stores. Dexcom could be using them, though, because the Transmitter is a completely solid assembly, with no chance of HazMat leakage.

Two other bits of reply: Li-Ion rechargeables don’t have any “memory” problem, in the way that NiCad batteries do. So the Receiver doesn’t have a problem there-- it’s just the fact that these batteries can only be charged/discharged a limited number of times before they “wear out”. But there is a shelf-life issue for the Transmitter: From the instant the battery is connected to the electronics, it’s listening for a Dexcom Receiver to send a “Give me your reading!” order over the radio. Until that message is received, it doesn’t have to turn up the Transmitter power to send the answer back; but it’s listening all the time.

Nearly all of Dexcom’s brains are in the Receiver, not the Transmitter.

I see a lot of upside in the one year warranty. Who would want to use a 4 year old CGM? Technological advances in the CGM field happen too fast. I am already looking forward to next CGM generation. For example, if Abbott came out with a Navigator that does no longer need calibration, would I want to be stuck with the DexCom for 4 years? Like MM pumpers waiting to get their hands on an OmniPod.

(I Removed that post in order to edit after the “15 minute” limit. Here’s what it said, including the corrections I wanted to make)

The Lithium-Ion rechargeable battery within the Receiver can only be recharged/discharged a couple of hundred times. (What I REALLY mean is that after you’ve been using it for a long time, it won’t store a lot of energy from recharging – it will run down very quickly.)

Lithium-Ion batteries are “interesting”. If you push one all the way up to 100% charge, as you would want to do with the cheap AA and AAA NiMh batteries you use around the house, you can suck more power out of it before it needs recharging. But, the lifespan (number of recharges) will be much better if you only push it up to 70% charge. We can’t control this-- it’s a Dexcom design decision, setting the value for “battery is full” Voltage which shuts down the charger.

They need to strike a balance between bothering you to recharge “too often”, or burning out the battery more quickly by pushing the energy storage “too high”. If you recharge all the way up to 100% maximum energy storage, it might wear out in less than 200 charge/discharge cycles. But if you pushed it to only 70-75%, then you can probably recharge it about 500 times. Sounds great, but I think Dexcom isn’t stopping the charger at that low a level-- and here’s why:

There is also a minimum level, which you need to stay ABOVE for maximum lifespan. You shouldn’t run a Li-Ion battery below about 30% of it’s “maximum energy level”; that’s likely to kill them even faster than charging “nearly full” does. So charging to only 70%, and asking you to recharge at 30%, allows to you use less than half of the battery’s “maximum” capability-- so it nags at you more than you’d like. Still, if you wanted the longest possible battery life, that’s how you’d get it.

(People who run their Notebook computers all the way until the Computer screams “Battery is almost dead, you must shut down NOW” keep finding this out… but hardly any of them bother to find out their Notebook batteries keep wearing out, and how to make them last longer. They just spend $$$ on replacement batteries, over and over. The biggest damage is when you fall into the last 10%.)

You really, really, REALLY don’t want to let it get below about 30%. (Recharging at 40% is even better.) The minimum voltage settings, and voltage settings for the 3 battery indicator levels, are also Dexcom design decisions. I don’t know what they really mean. I could tear up the cable on one of my chargers to find out, but even I have better things to do… usually. :wink:

But when I’m running with very few alarms, I don’t see the 3rd bar vanish until the end of day 2. That’s a lot of run-time spent, so I’ll guess that when you see even ONE bar missing on the battery indicator (two bars left), and you NEED to care about Receiver battery life, then you want to plug it in ASAP.

I used to plug my Dex in all night long, every night, but since I’ve learned the lifespan costs of pushing these batteries to close to 100% maximum energy storage, I’ve switched to letting it go until the 3rd battery bar goes missing. Then, I give it about 70 minutes of charge time. I’ve no idea if this will REALLY cause a significant change in lifespan or not, because Dex has always come out with new models before I’ve worn out my old ones.

Battery replacement? No way. I think that they attach the four screws, from the back, into the top case shell with a strong glue. And they probably also glue the long seam, between top and bottom all the way around. (I’ve seen this done in LOTS of low-power “no serviceable parts inside” AC to DC power supplies.) It’s quite difficult to cut them apart, and even if you did, the battery is very likely glued to the circuit board. Replacement would be difficult, even for me.

Now, Elizabeth, I’m sure that you’ve noticed: Pumps use replaceable batteries. So do Abbott and Minimed Monitor/Receiver units. (Minimed’s non-pump “Guardian” model is basically a 522 pump, with the R/T feature, but with the pump-related stuff left out.) MM uses an un-replaceable Li-Ion battery in MiniLink, but only Dexcom uses un-replaceable batteries in both units of the CGMS system. That problem will “go away” for the Receiver, of course, when Dexcom’s pump making partners get their combined Pump/Dex Receiver products to market.


I’ve opened my Seven + receiver to clean out “pocket” dust and debris that migrated to the inside surface of the viewing window. Since I’m an electronic technician I decided to just go ahead and disassemble the receiver. While it’s very simple to take apart and put back together, I did take the usual electro-static discharge (ESD) precautions by working on a grounded mat with a wrist strap that grounded me to the mat.

To remove all you need is a #6 Torx screwdriver. The four screws on the back release the back shell from the front. There was no glue or any kind of adhesive binding the two halves of my receiver together. Manufacturers do change things from time to time so your mileage may vary. I received my Seven + system in September 2009.

The proprietary battery connects to the circuit board with two relatively small gage wires. I don’t remember if the battery wires connect to the circuit board via a solder connection or a snap together connector. The battery is not glued to anything. Replacing the battery would be a relatively simple operation for a technician.

I know that Dexcom would discourage this kind of activity and would probably disallow any warranty if they found out. Curiosity, however got the better of me. I didn’t observe any “tell-tale” fasteners or tape that serve as physical evidence of entry.

I’ve enjoyed reading your posts, especially the level of detail that you examine most issues.

I didn’t mean to imply that I prefer Minimed’s CGM. Quite the opposite, actually. As someone who has used both, I am very comfortable saying that Dexcom is a far superior product.

This is good to know. I had not been able to find out about the transmitter battery from Dexcom’s website. All I could establish is that it never needed to be recharged, which was a bit of a mystery.

Terry, at this moment it’s ME with all the enjoyment, delighted by the details and info which you just provided in this post. (Kudos back atcha, man!)

I’ve been chicken about chopping into a still-working, still under warranty 7+ receiver. But I’ll use your hints to open mine up after the warranty expires, and before the battery is COMPLETELY dead), in order to inspect the battery and measure it’s electrical properties. I might even see an identifying label on it…


When I used MM, Minilink hadn’t been invented yet – and the big, fat wire to connect the Sensor was really short. MiniLink might be kinda bad, but the first implementation was even worse! :wink:

“Spending $1,000+ annually on top of the huge cost of sensors really seems excessive…”

I don’t know how many of you listen to DexCom quarterly earnings calls. DexCom is in business for 10 years and has lost money in every quarter straight. If I remember correctly DexCom has lost 250 million dollars so far. I want to say THANKS to all the investors who subsidize my DexCom.

I have Aetna as well and they covered my Dexcom and Omnipod at 100%

I think it depends on the plan you’re under (maybe also the state.) I have an expensive plan that I got because covers most DMEs at 80% (the less expensive, although $100 less per month, only covers 50%) But for whatever reason, the more expensive plan only covers CGM expenses at 50%. I’m guessing it’s because it’s not as critical as things like glucagon and pump supplies. (Don’t get me wrong! I’m happy they cover it at all…)

My Aetna plan covered the Dexcom receiver, transmitter and sensors at 100%. It also covered my OnmiPod PDM and pods 100%. That helped because my co-pays on my prescriptions are high, $15 - $30.