Hi,
I have a muon and its battery. I did not use them for a week.
I power the muon up and the battery reads very low. Ok, I had it almost full last time.
I leave it there, I disconnect the USB wire to my computer. I check the battery some time later, and the battery charge (as calculated by the console) continues to go up and up and up.
Nothing is charging it. This is not the first time I see this.
What effect am I observing?
Thanks
Hey Graham, thanks for the hint, could that be possible eventhough I did not move the battery around? I mean, it's been in the exact same place.
The MAX17043 is a model fuel gauge, meaning it monitors the battery voltage over a period of time and uses a model to create the SoC, which is not linearly related to the voltage. It also adjusts the parameters over time, based on performance. There are initial characterization inputs based on a specific battery, but I don't think the Muon fuel gauge was calibrated to its battery. It should eventually adjust to the specific battery that is used, but may provide some strange results until it does.
Thank you for the explanation. Where can I read more about calibration?
@gusgonnet can correct me if I'm wrong, but I believe the 18650 cell has already been dynamically exercised for many days while the Muon spends most of the time in Hibernate Sleep.
The fuel gauge's SOC approximation (actually, DeviceOS's result) does not appear to be getting any better.
Is it possible that this will be something we just have to deal with on a Low-Duty-Cycle Muon using Hibernate Sleep ?
The MAX17043 datasheet has some information, but I think it's mostly under NDA. Also the configuration parameters aren't really user-settable. We have to send the battery off and we get back a small binary configuration file. But this should only affect the initial performance; over time the model should adjust. The initial devices with a battery like the Electron weren't configured at all, just the default settings were used.
The battery doesn't get exercised when there's external power to avoid unecessary charge-discharge cycles. The power goes directly from VIN/USB to power the device through the bq24195.
That's not the case for our testing.
Intermediate Solar Recharging with several (no Solar) discharge cycles followed by Solar recharge cycles to full. The 18650 was dynamically exercised.
I was mainly referring to a main voltage power supply.
That would only apply if you have sufficient solar all the time, at a sufficient voltage and current, which would be unusual.
