Voltage goes up with AGITATION?

[Ready2Dye]

Why does my voltage raise when I turn on the water/air pump (from Caswells's LCD kit) ? It will go up anywhere from 1.0V to 1.7V within 90 seconds or so and it stays there for the rest of the run, if I turn it off (agitation) the V's go down.

Has anyone else noticed this?

I use a cc/cv PS set on cc.

Thanx

-Daryl

[Ready2Dye]

BTW- I don't mean it goes to 1.0V or 1.7V... I mean it increases by that much.

ex. no agitation 12V with agitation 13.7V

any ideas? or is this normal?


The temperature stays the same about 69-72°

If I have it right and please correct me if I'm wrong but Voltage is relative to acid/h2o bath temp ? Is it the lower the temp the higher the V needed?

[sswee]

That's normal. You could do the same with no agitation by rocking the part back and forth.

Yes you're correct on the bath temp. Colder = slightly higher voltage.
If I remember right there will be from 4 to 6 volt difference in a 10 degree change.
SS

[Ready2Dye]

thx sswee, I appreciate it.

I put some thought into it overnight here is what I think (uh oh):

The electrolytic bath is being agitated (resistor) so... to supply the cc the ps ramps up the V to push through all the bubbles - or something

regarding the bath temp since the water is colder the molecules are moving slower and are far apart - right?

so in order for the constant current to be supplied the V's go up cuz the resistance is higher than when the bath is warm or dare I say, HOT; then those molecules would be bouncing all around really close. The current would then have a much easier time getting around- let me know if I got this or not.

[M_D]

As sswee said, it takes higher voltage in cooler electrolyte for a given amperage. A soon as the electrical current starts to flow, the temperature begins to rise at the part/electrolyte boundary, even if you don't notice a difference in the overall tank temperature. Whether you agitate the part by hand, or agitate the solution with a pump, the result is the part/electrolyte boundary heat is dispersed and the volts go up. If or when the extra agitation ceases, the temperature at the part goes back up, and the volts go back down.

Depending on the level of agitation, there can be quite a disparity between the electrolyte temperature away from the part(s), and temperature of the part and the electrolyte close to the part. The temperature of the part surfaces is more important than the general tank temperature.