Using voltage to gauge conditions can be misleading. If you know what the voltage should be for a given setup, and monitor all conditions, it can help to troubleshoot. If the voltage is suddenly way high (possibly caused by a bad connection or over estimation of amps needed), or even low (under estimation of amps needed), it may point you in the right direction.
The problem with comparing voltages from two individual setups (at the same current density of course) is everything changes the voltage some. A well-deoxidized part will run a different voltage curve compared to an oxidized one. Various alloys change the peak and curve also. Low acid concentration raises voltage, and higher acid concentration lowers it. The effect of general tank temperature was mentioned by sswee.
One thing else that is not common knowledge is the agitation level changes the voltage peak and curve, by as much as 2-3 volts and commonly 1.5 volts, at least in our operation. If you want to know why, the sentence before this paragraph contains a clue. (As a note, we run higher current densities for type II which amplify things such as voltage and temperature issues which make them easier too see) I will comment more latter, but thought it would be interesting to see if someone else either knows or guesses what the connection is between agitation and voltage is. It is one reason why the voltage sometimes goes up as time progresses, and other occasions it never does but just drops from the beginning. I’m fairly certain Fibergeek knows, as he has all but said it in other threads.
When you add up all the potential variables you can see why a seemingly large variance in voltage shows at times when comparing notes across 2 individual setups. Sometimes it points to a problem and sometimes it doesn’t.
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