Tandem t:slim charging anomaly

Type 1 and LADA
1

Yesterday I charged my pump. I used the same USB charger and cable that I have used for the past two years. But this time when the pump reached 70% charged I received a notification saying

Power Source Alert
The pump cannot charge using the current power
source.
Please try a different power source.
18:21, Today, Friday, Mar 21

The battery level icon on both the pump and in the t:connect app indicated that the battery was at 70% and no longer charging.

I unplugged the cable from the USB charger and then plugged it back in. The pump pinged as if charging and displayed the lightning bolt that indicates that it’s charging for 2 or 3 seconds, then gave me the “Power Source Alert” message again. The battery was still showing 70% charged.

I unplugged the cable from the USB charger and plugged it into a different USB charger. Same behavior - it pinged and showed it was charging for a couple of seconds and then again showed the “Power Source Alert” message. The battery was still showing 70% charged.

I tried a powered USB hub and a computer USB port. Both exhibited the same behavior (possibly popping up the alert more quickly), but after the second of these attempts the battery reported it was charged to 75%.

To rule out a cable problem I found a different cable and plugged it into a third USB power supply (Apple instead of Google branded). And again the pump pinged saying it was charging and then popped up the “Power Source Alert” message. But this time the battery reported it was at 100%. Since there’s no way that that USB charger delivered enough energy to charge the battery by 25% in 1 or 2 seconds, I’m left believing that the battery was likely at 100% ever since the original alert and the “Power Source Alert” messages were bogus throughout.

I haven’t updated to the latest software, my pump is running version 7.8. I’ve reported this to Tandem, but they haven’t had time to respond.

Has anyone else seen behavior like this?

2

From reddit 2 years ago

Plug your pump in, ignore the alert, and let it charge for 30+ minutes. It will self correct.

This is a known software bug, and was fixed in the remote bolus update.

!Thanks for your input. I finally connected with Tandem tech support today and the direction on fixing the issue was as you described. He didn’t say anything about the update required to bolus fixing the problem. I haven’t yet updated my pump software to bolus from my phone, and may not as I’m nervous about doing the update and really see little benefit for me to bolus from phone rather than the pump. I did charge my pump earlier and didn’t get the alert so for now hoping I just don’t see it again.

3

It self corrected after 6 charging attempts lasting seconds each. Much less than 30+ minutes. :slight_smile: The statement that it was fixed in the remote bolus update seems suspect, since my pump originally shipped with that feature working.

The Tandem technician shipped me a spare Tandem cable and charger, probably assuming this has a small chance of fixing the problem or at least making me go away. We’ll see.