To be frank, I never really liked my trustfire 14500s. Half of them were already dead upon delivery; a couple more died silently stored in the battery box. Now I have checked on them again, and whilst seven of the remaining eight show a steady reading of 3.98 to 4.1V, once cell doesn’t.
The DMM (professional Gossen Metrawatt) shows alternating readings, quickly dropping from 4V to 3.9V and back up to 4V, and so on, at a rather high frequency.
I am wondering if it wouldn’t be best to just dispose them off altogether?
Your meter or the cell is bad or intermittent.
It is correctly responding to some type of waveform or oscillation.
It is toggling because the true voltage is between the 3.xx and the 4.xx readings you posted.
Since you’re reading voltage, this problem being caused by tarnish on the connections is not likely - a voltmeter draws almost no current.
You could try lightly loading the battery, zum beispiel at C/100, and see if the symptom disappears.
I ordered those from manafont. Their protected 18650 t’fires are ok, still, the protected 14500s were troublesome from the very start.
Btw, I just measured the voltage again, using a fluke DMM at work, no change - the reading is trembling like the oil pressure gauge on my clapped-out 302.
Hook up an oscilloscope. The AC coupling mode might give you a better image, depending on the period of the oscillation. I’d think the protection circuitry oscillates under no load.
Yes, I can almost see most of the qualities of this circuit being optimized at the heavy current end with pretty loose specs, if any at all, at the low current end.