How Long Does a G5 Transmitter REALLY Last? **UPDATE-Transmitter Died** UPDATE-New Transmitter ***UPDATE-2nd Transmitter 😭



I am on day 149 of my first G5 transmitter. I have @docslotnick 's record of 191 days to beat.

VA = 314, VB=303 and Resistance at 641.


@Aaron GO AARON!
Be sure to keep us posted.


The basic equation for this is:

I = V/R

I = the Current; in a non chargeable battery you can think of current as the fuel.
V = volts
R = resistance.

Doc, so when talking about batteries that can’t be recharged, the lower the system resistance the faster the device will discharge. In this case I think the Resistance that is being reported to you is the battery internal resistance, which is a whole deeper and more complicated topic to tread into.

For the future, I would only look at the voltage to help you predict the end time. It looks like once the battery is unable to maintain the full 3.0 volts you have a couple of weeks left.


We should erect a statue to this transmitter!

“She/he died to further humankind’s striving for knowledge. May it rest in eternal peace, with voltage nevermore, nor current to its batteries.”

Unless, of course, you are planning to get a new battery into the thing :slight_smile:


I spoke with Dexcom Technical support today and discussed the G5.

Dex Tech Support said that having more devices connected to the G5 transmitter at the same time will cause increased battery usage and hence decreased transmitter life.

So with Doc only running his smart phone against the transmitter, he could reasonably expect the G5 transmitter battery to last longer as opposed to somebody else running both the Dexcom Receiver and a Smart Phone against the G5 transmitter at the same time.

Dexcom also said the X2 will connect to the G5 as a receiver - not as a smartphone. Apparently there is some difference. The X2 additional Dex functionality will allow the Receiver to be completely replaced by the X2. This would be in line with the Tandem t:slim G4 which was shipped with the Tandem pump, the Dexcom G4 transmitter (and sensors) but no receiver. So one would assume that the standard testing would be with the X2 and Smart Phone connected to the G5 transmitter but without the receiver also being connected.


@Michel I would like to try out a transmitter with replacement batteries. But I can’t seem to find the replacement services at the moment. They seem to appear and disappear like sprites.

Also, I’m going to order some new transmitters. My insurance OOP has been met so they are no cost to me.


Do you ever get confused at such point (max oop) and try to figure out if that is a good thing or a bad thing?


I look forward with great anticipation every year for the day my insurance OOP is met. This year was about a month late because of the way they calculate it and the increased amount ($5000).


What did they give as a reason for the larger battery drain? I can absolutely understand that the system has two communication pathways, i.e. Bluetooth to phone and their proprietary connection to the receiver and/or the Tandem pump. But how could a second device receiving the information take more battery power from the transmitter?


In this call we did not get into the “reason” other than “# devices”. In any event, I know the G5 has two-way communication. I am pretty sure the G4 was only one-way but I am not positive on that. For sure the G5 is two-way.

So the G5 is not simply doing a multicast once every 5 minutes and whoever is listening picks it up. Rather each device can poll the G5 for not only the current data point but as well any data points within the past 3 hrs that were missed (well devices that support that - the current receiver does not, the smartphone app does and the X2 pump does).

So the G5 is actually doing more transmissions with more devices.

Unfortunately some of that is guesswork and some is what I picked up from Dex Tech Support (from multiple calls). And I don’t remember what was guess and what was Dex tech.

So if anybody has information to the contrary - feel free to contradict.

Also I do not believe the proprietary connection between the transmitter and the receiver is present any longer. That was on the G4. With the G5 this is also Bluetooth. I am pretty sure that is fact based on the FCC testing documentation of the G5 that I read through. Which seemed very explicit.


Ok, 2-way communication, that makes sense. That also explains why it would drain the battery to have more connections. I hadn’t considered that.


That could also explain the longer physical life with the xdrip which I believe has been said to only work properly when using a single smart device and no receiver - hence - one device? (Ignoring the obvious logical shutdown when on Dexcom approved receiver and app.)

While Dexcom has (most certainly) tested the battery life of the G5 and expects it to last 3 months (and 3 weeks) with both the receiver and a Smart Device.



Really useful information @Thomas, thanks for doing the legwork on this!


Your further explanation is correct. My understanding is that each receiving device is pinging the transmitter for a value, then receiving that value. You could ping it every minute if you wanted – but there will be an extra cost in transmitter battery life.


I believe that the FB groups listed in the Dexcom transmitter replacement thread also apply to the G5.


I guess I’ll never find out, because I never have nor willI I ever have a Farcebook account.


Would you like me to check them out and find an email for you?


@Michel Thank you Michel. That would be great!


But then how do you share pictures of your breakfast with 1000 of your closest friends???


Don’t forget trying to impress your friends with “once in a lifetime” selfies. We here in Oregon are especially sensitive to this since we recently had a couple of young women who fell off a waterfall together and died, and the only reasonable explanation (although it is speculation) is they were trying to take pictures from the top of a waterfall.