Accurate time on Minimed 670g

I’ve noticed time drift on my 670g. Every 2 months, it gains about 5 minutes. I normally just adjust it back to the correct time. Has anyone else seen this and have any insight into what is going on?

@kkavolinas hi Kathy, the clock chip that is on your pump is off a little. Please consider reporting it to Medtronic and ask them if it is inside the tolerance for the onboard clock. If “no” then ask for a warranty replacement. In my opinion, it is off by ~.00002 but it’s enough to be annoying and since the basal delivery depends on that clock it’s worth asking. Cheers good luck

@joe Hi Joe. Thanks. I called Medtronic. They are replacing the pump. There were absolutely no problems other than the tech had to ask how to handle the problem. Apparently this is not a common problem and 5 minutes over 2 months is definitely out of tolerance. Now I get to start auto “learning” me again. Yippee!!

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OMG!!! I am so glad someone finally brought this up!!! I have the same problem but my pumps time changes by 8 min each week!!! If anyone know how to fix this please let me know!!!

@sugarbug1022 hi Grace, as above, it could mean your pump has a malfunction and needs to be replaced. there is no fix - please call or have someone call Medtronic and talk to a specialist.

Hi Grace @sugarbug1022 . You need to call Medtronic. When I called it took about 5 minutes (the tech needed to consult someone) for Medtronic to decide to replace the pump. Definitely a malfunction. The only headache, if you are using auto mode, is with a replacement pump, you have to go through the pump learning process all over again (yippee).

Also, if you call and they replace it, take care to record (take pictures of the pump (with serial number) and the return envelope tracking number) and note when and where you sent the package from. Medtronic isn’t very good at keeping the paperwork straight on the return and you don’t want to be charged for not returning the defective one

Medtronics Engineers chose to save $0.75 by using a crappy (low-cost) crystal in their system clock’s crystal oscillator circuit. And their software designers didn’t add any functionality to correct for clock drift (add 1 sec per day, etc).

Or, maybe the circuit designer just used the default circuit off a clock-driver IC application note without really bothering about how the type and specifications of the quarts crystal will effect oscillator performance (longterm clock accuracy, drift and temperature coefficient).

Electronics design at most companies is like a sausage factory. You really don’t want to know how the sausage is made. Gives you a warm fuzzy feeling inside, doesn’t it? To know your life depends on this crap some poor overworked 24 year old kid (“engineer”) threw together as fast as he (she) could.

I wouldn’t bother returning your pump for a new one. You might get lucky and get one with better clock performance (especially if yours is particularly bad), but your new pump will still have the same crappy circuit design and software that causes this issue. You might get lucky and get one that keeps more accurate time, but in my opinion, it isn’t worth the trouble. Just update the clock once a week, and say goodbye to Medtronics when it is time to purchase your next insulin pump.