Lesson Learned: Don't wait on Transmitter Batteries


There nothing wrong with your communicating skills. Dealing with the D has just turned us all into a bunch of nit-picky SOBs! :wink:


They do 3 months now because of the actual battery life. The G4 uses low power RF to transmit data to the receiver. The G5 is using Bluetooth to the phone, and RF to the receiver. The batteries simply do not last with the extra power usage, and they need to ensure a certain level for both “communications links” to continue to work. This is also why the Transmitter is larger.

Why they don’t have rechargeable is the same problem. The technology isn’t there for a rechargeable battery to last that long. You would be recharging once every couple of days. The devices my company makes with Bluetooth technology (a medical device as well) lasts 4-7 days on a small battery like contained in the G5.


Not that this matters that much, but I do not think what you are saying is correct. G5 is using just Bluetooth low energy (BLE) to send bg data out. There is no other RF there at all (as a side note: BLE is also RF, just a different frequency band, and completely different technology).

Not really. G5 is their first BLE design, which was rushed out a bit. Transmitter and battery can be smaller, and will be smaller in G6.

Respectfully, I disagree. The transmitter could be rechargeable, with couple of weeks of life at least, in my estimate. But then Dexcom business model goes down the drain, so a rechargeable Dex transmitter will probably never happen. The fixed transmitter lifetime (3 months + some days) is also dictated more by their business model than by technology limitations.


I’m still totally confused. Dexcom WILL NOT REPLACE a transmitter that is still under warranty and still working. They are warrantied for 90 days, but will continue to work until the hard set shut off at 112 days. Yes, you may in fact be “without a backup” when you get to the second transmitter of your 6 month supply, and yes, that sucks, but it is what it is… it’s the exact scenario you’d find yourself in as a new G4 user for the first 6 months, you would NOT have any kind of backup at all and it would be ok. If you do have a transmitter fail (it happens - I’d had two failed G5 transmitters) or one that fails to start up (has also happened to me) they will replace it and overnight you another and it’s not that big of a deal. Annoying, sure, but it is not exactly the end of the known universe the way you are making it out to be.

When they make reference to “call for replacement” they are actually urging you to place your next supply order through insurance, they are NOT asking you to “call and get a free one on us”. That is not how it works.


I get my G4 transmitters from Animas UK. I don’t know if it is different in the States, but for the G4 transmitter the warranty starts from the day you order it - NOT from the day you activate it. This is a major PITA as I have found that transmitters will generally exceed 6 months but then fail without warning. It’s useful to have a replacement on hand, but if you order one, the warranty is ticking down even before you activate it.

You would also be lucky to get a replacement sent overnight. Animas don’t treat transmitter failures as urgent so it can take 2 or 3 days to send a replacement, especially if fails on a Friday evening.


I stand corrected on the first point @Dragan1. They only use a BLE radio.

They may pick a better BLE chipset, with lower power usage, but they will be limited on battery size. The current batteries are low voltage batteries with an expected continuous use life of 734 hours. At 1 reading per 5 minutes, they are using roughly 538 hours of drain over 112 days, not including broadcasts, pairing, connections, and such.

They have to make sure they end the battery before voltage drops so low the transmitter cannot communicate across the dual devices.

We can disagree, but the cells to support that are larger than you think.

I agree, and I disagree. The rechargeable battery in a medical device isn’t there yet. But like most things, their business is reliant on us purchasing more disposables. If you think about it, the Medtronic transmitter is good for 1 year minimum. I’ve gotten 2 years out of it. They need recharging every 10 days, but are bigger than Dexcom and are on lower power RF.

Guess the geeks rabbit holed this thread enough for now.


This is exactly how things work in Canada, too, with Dexcom distributed through Animas Canada.


Agreed. You’ve made good points, thanks. To continue the discussion would require some :beer: Cheers!


Your post was very helpful! I didn’t know it was 3 months after activation. My daughters is 4 and this is new to us. Her Dexcom came off at my mothers house and we didn’t find it until the next day. I didn’t think anything of it and I just activated her new one that night.
Well the battery life on both of them expired before she was due for a new one. This explains why. Although we didn’t one of them for 3 months, it still expired. I can’t believe no one explained this to us. We never even had a training for this by her dr.
How do you go about getting a new one without paying out of pocket? What do you suggest saying if I call them?


Also, is there anyway for them to actually know when you activated it? So if I said I activated it 2 months ago and it failed, would they really know? I really need one ASAP and can’t pay out of pocket.
I didn’t read all the responses, so I am sorry if I am asking a question that was answered.


You could call dexcom support, and explain you lost the first transmitter, and had to start the second one early. They may offer a discounted cost to replace the lost one. I recall hearing that if a receiver was lost or damaged getting wet, they would offer a one time replacement at a discounted cost.
If you claim it failed within warranty, they would ask you to return it to them, so I would not suggest that approach. True failures they want to analyze to determine cause and possible defects.

For future, you may want to check with home/renter’s insurance, and see if that could be added to your coverage.


The way it’s been explained to us is that they (your insurance) will not cover the cost if it doesn’t meet one of these criteria:

a) The transmitter received an error and is no longer functioning (they will send a replacement when this occurs…but the replacement isn’t…free…it’s covered by insurance., or…
b) You call them AFTER you have received the “your battery is dying” message.

If you call them before this time, they (your insurance) won’t cover new transmitters. We are just now coming upon our first actual new shipment because our second (we received 2 up front when our son was diagnosed) has now finally reached the point where it just displayed the “your battery is dying, you have x days left” message.

So, once you receive that message, call Dexcom and they’ll run the order through your insurance.

Also, is there anyway for them to actually know when you activated it?

Regarding when you activated, yes…it’s one of the menu items. Look in the “Transmitter” information screen.


Well this thread was an interesting read :grin:

Some info that may be of interest / helpful to G5 users: The 90 day+grace cutoff is implemented in the receiver, not in the transmitter itself. The transmitter keeps right on merrily working until the battery dies. The receiver keeps track of transmitter serial #s (that 6-digit alpha/number you enter when binding the transmitter to the receiver on initial use of the transmitter), and stops accepting it after it expiration time period.

As such, you can keep using a G5 transmitter until it dies with the Android opensource apps like xdrip and its variants. I haven’t been using xdrip long enough yet to see how long I can go with a G5 transmitter – maybe someone else here has a report.


Please let us know when you do find out; I’d be very interested to know.


Will do. I learned this myself from the xdrip-plus gitter channel where its been discussed (with testimonials).


I am going through my first transmitter change with Dexcom. Oddly enough, I started getting calls from my vendor that I had “CGM items out of warranty” before my dexcom alerted that I needed a new one. I am not sure if it matters though, as my Dexcom is considered Pharmacy, so a new one is just $60. I restarted my current sensor on Saturday, and my Dexcom said this would be my ‘last sensor’ with this transmitter. Kind of frustrated that it really is only a 3 month life span.


Danielle, if you have an Android phone and are willing to give the open-source app xdrip+ a try, let me know and I’ll help you get it set up. You’ll be able to keep using the transmitter past the 3 month window.

Also, if you can ditch the extra device (Dexcom receiver).


Does anybody actually get the “battery low” warning? After 3 years of using the G4/Animas Vibe combo I am on my fourth transmitter and none of them have actually given a warning prior to stopping working. One of them started to give repeated “transmitter out of range” warnings (after about 11 months and even with the pump next to the transmitter). Two just gave continuous “ANT” (out of range warnings). One at about 7 months, the other at 5 months (replaced for free). My current transmitter is around 11 months old and working OK.

Of course failing without warning means a 2 day wait for the replacement. Despite cutting into my warranty (which starts from the date of ordering not activating), I ordered a spare before going on vacation because I was going somewhere where I wasn’t confident that they could send a replacement if it did fail.


I get it every time.


We upgraded to the G4 a couple of weeks after its release. We’ve only had the low battery warning on one transmitter, which died last January.