Is Buying a NEW but Outdated G5 Transmitter a Mistake?

I am concerned that Dexcom will force me on to the G6. If they do, I will simple begin accumulating G6 sensors and transmitters, which is fine, while still using my G5 sensors and transmitters. Nonetheless, I will need to acquire a couple more G5 transmitters to use up my G5 sensors.

I just purchased a new but older G5 transmitter from Amazon for $125.00. After receiving it, I noted that it had a SB(?) date of 8-10-2016. I have noted from posts in this forum that Dexcom transmitters lose their overall duration even while sitting unused in the box.

What would generally be the Voltage and Resistance of a newly manufactured and unused transmitter?

If I do keep this older transmitter, I will look at the Voltage and Resistance after I insert it and compare them to a new one.

Ultimately, should I return the transmitter based on the SB date? What does SB mean? Who knows, the transmitter may not even be unused?

Looking for general rule of thumbs for transmitters as I have a few “in the box“ transmitters and am concerned they may not last as long as I thought.


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The SB date is the Ship By Date. Have you read these topics below? Based on the comments in these threads I think it’s highly unlikely the transmitter still works. According to @Michel a Dexcom agent admitted that 80-90% of transmitters fail when you start it 12 months after the manufacture date. If possible, return it to the seller.


There are services that will put a new battery in the G5 transmitter for you. I do not have details, but I know someone who uses that service. I can try to find out.

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Thanks Boerenkool and Eric. Sounds like I have to rethink stockpiling transmitters. And I should definitely return this one. Do either of you know Voltage and Resistance for new, just built transmitter? At least I can test the ones I have stockpiled with this information.

Hi @RCA221
I sent you a PM with the name of the group.

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Thanks Eric. Here about two weeks and love this site.

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You are welcome.

I am not really much of a Dex guy. There are a bunch of people here who know all the tricks. I just let the Dex wake my up at night when I am low, that’s about it for me. :man_shrugging:

I know you have already met @docslotnick on the xDrip front!

Yes, both of you are terrific and I am consuming your posts. :grin:

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Let me know too

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Thanks Sam. Were you born in Alaska? Haven’t filled out profile yet. Too busy figuring stuff out! :stuck_out_tongue_winking_eye:

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No, I moved there from oregon for my job mostly, and actually just moved to wa state recently for my wife’s work… I still commute to and from alaska for work

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Could someone let me know if I have properly digested this? :face_with_thermometer:

I have four transmitters. After reading through the articles Boerenkool attached and going back to 2018 posts from y’all, I think the warranty on transmitters is as follows;

If from Dexcom, 90-day warranty begins 5 months after Dexcom ships to customer.
If from a distributor, 90-day warranty begins 12 month after Ship By date on box (SB date is date transmitter is required to be shipped to customer which equates to 242 days from transmitter built date.)

Is this right or do I still need some feeding! ? :roll_eyes:


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I think so, I don’t think there is any point at all in going beyond the ‘use-by’ date, which, for the latest G6 (with a bigger battery IRC) is 12 months after the manufacture date.

I believe the nominal battery voltage is 3.1V (this is from memory). The ‘at rest’ reading from the transmitter should be close to that initially; my G6 (8G series) is showing 3.08V on 15 transmitter days. The low voltage (the voltage under load) is 2.91V on that transmitter. I think the things start to get pretty useless below 2.8V, maybe 2.7 for the load voltage.

If you want to replace the battery, the option @Eric quoted, it shouldn’t matter how old it is, or how dead; modern day electronics decomposes over periods of around 100 years or more from radiation damage, modern cells are not that good.

CostCo were selling Dexcom transmitters at a much more reasonable price, but that might only be the G6 ones:

At the time I verified the transmitter price separately (there’s a fud post on this somewhere) and it seemed correct however, since I’m always OOPMaxing these years, I don’t need to purchase from CostCo.

I suspect if you have a few dead G5 transmitters around to practice with you could Dremel one out so that it has a replaceable cell. The cells in question are hardly expensive. It would also be possible to make the whole thing rechargeable and that is probably more green, of course it means plugging in for the recharge overnight. In any case all these approaches only work if Dexcom isn’t using an EEPROM or flash in the G5 to store data permanently, but given that other people have been able to create the zombie transmitter (or is it the Frankenstein transmitter?) this probably isn’t the case.

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jbowler, thanks for the post and info on Voltage. I think I will try these “older” transmitters and see how they last or if they might be dead. I have one I didn’t list that is 2015/2016.

So if transmitters do decay in the box, I think that’s been established, the question is how much and how fast. Since one of the reasons for moving to xdrip app is to prolong sensors and transmitters with relative ease, I wonder if it is worth even trying to reset the transmitter.

For those of us on Medicare (and some on private insurance) we get a transmitter every 90 days. If they last 112 days or 193 days. we will eventually run into a situation where we have transmitters in boxes, maybe two or three. Maybe its not worth trying to lengthen their life.

Anyway, I will put in my 2016 transmitter next and see what happens.

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Not quite right. There is a 90-day warranty, if you start the transmitter within 5 months of Dexcom shipping it to you. If you start the transmitter 5 months and 2 weeks after Dexcom shipped it, then you have no warranty at all, even if the transmitter fails after just 10 days of use. I got thwacked by the blunt end of this rule.

And what if a distributor ships it to you?