At what point does the voltage for a battery in a simucube wireless wheel become an issue? Should I trust the voltage as shown on a multimeter or go with what shows the highest in the configuration tool? - They are different!
The battery I’ve been using in my rim for a year shows as 3.613V on my multimeter shows 3.56V in the configuration tool.
Replacement batteries that measure 3.66XV on the meter show up in the 3.4XV range in the configuration tool.
Here is a video to try and show what I’m talking about:
The difference is likely to come from tolerances and the fact that a multimeter measures the battery with it’s completely unloaded, while in use there’s small current drawn which is likely to give slightly lower reading.
Also, depending on the battery chemistry there can be minor variations in the output voltage. I’m making a (dangerous) assumption that the battery is not from same manufacturer as it’s different color.
The issue is not that much of voltage but current that can be drawn from the battery. When the wireless module is connecting, it’s using much more current than in normal operation, however only a short period. During this the battery voltage can drop enough to cause connection issues etc.
And, it is also a feature of the 3.6 V battery and its chemistry, that the voltage will stay very, very constant until the final drop. It will still show 3.6 V even if it is completely empty. It is impossible to know the state of charge from just looking at the voltage.
We implemented switching over to the most efficient power mode in the wireless connection only after a few seconds in an attempt to detect this battery - whether it drops under this high power transmission condition or not - but it is still not 100% reliable.
At what voltage (as seen in the configuration tool) is it recommended to replace the battery? Or does the chemistry keep them in about the same range until it suddenly drops off a cliff?
In other threads I’ve seen mention that at 3.4V the battery is suspect, which is part of my concern with the “fresh” batteries I have. The one in the video is indeed a different brand, but I also have several of the same purple Pkcell brand (which advertise a 10 year shelf lifespan).
My concern is all the “new” batteries I have measure 3.66xV on the meter but show 3.4xV in the configuration tool.