neilmc said:
I'm not taking much notice of the resistance value on 0v cells until they have some charge in them (if they will take a slow charge at all without heating up).I do test to see if they are open circuit. If they are open circuit, they're trash.
I always thought I knew what open circuit means. I never came across a german word for open circuit but I just found it:
https://dict.leo.org/englisch-deutsch/Leerlauf
I never saw the word Leerlauf being used in this context, interesting. I guess hardly anyone here knows that Leerlauf applies here, unlike Kurzschluss which is german for short circuit.
You say you're not taking notice of the resistance, but isn't testing for open circuit exactly that? Isn't open circuit a high resistance connection up to a connection break (when the circuit is open, literally) with almost infinite resistance and the opposite to a short circuit?
The cell I tested yesterday, where I said it had a resistance of 6000 Ohm, actually has 6 MOhm, I've been reading this wrong. So it is 6.000.000 Ohm, that is a lot and definitely open circuit?
Continuity then is a connection between two points and more like a short circuit than open circuit. The threshold for continuity on my MM is 20 Ohm. If you test the cell for continuity with a MM and put the negative probe to the cells negative terminal and the positive probe to the positive terminal and get continuity between them, the cell has shorted and can't be used anymore. So is testing for open circuit is done by testing for continuity or by testing the resistance? Continuity is more like a resistance quick check, so to say.
And is this comparable to a charged cell which should have a very low resistance? I'm not getting any continuity on a charged cell, which is good because if I did then there is a short circuit, but I do get continuity when the polarity is reversed, i.e. negative probe to positive terminal and positive probe to negative terminal. That doesn't happen with my 0V cell (of which I "sadly" only have one at the moment, quite s small sample size). And I never get any measurable resistance which probably makes sense as the internal + external resistance of the cell should barely reach the minimum the MM can measure which is 0.1 Ohm + margin of error so probably more like 0.2 Ohm.
So, with all that in mind, what are we looking for at a 0V cell?
Continuity is bad because the cell would be shorted, so low resistance between the terminals is bad. But open circuit, high resistance, is bad as well. Does this make any sense?