Announcement

Collapse
No announcement yet.

Peak voltage ?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • R-Wells
    replied
    yes I did build a make shift box out of scrap materials.
    It just incloses 3 sides of the tank, no top or bottom,

    Rusty

    Leave a comment:


  • sswee
    replied
    I haven't had time to get to Home Depot yet. Did you build a box around your tank?

    Leave a comment:


  • R-Wells
    replied
    Hey sswee,
    I understood you , I just didnt make myself clear that I wanted to discuss theory.
    For your info, my little AC unit is doing a good job at the moment.
    I have run two 2.4sqf parts back to back at 4.5asf with no more than a 2° temp increase. ( start at 70° finish at 72°).
    Yesterday I ran 4 parts (aout 1.4 sqf) at 6asf back to back at 70° with no temp increase at all.
    I kinda figure this will change as summer gets here and the ambient temp goes up another 20°.

    I was runing two fairly big aquarium pumps, when I changed to using the shop compressor i saw a immediate increase in voltage of 1-1.5 volts.

    Rusty

    Leave a comment:


  • sswee
    replied
    Thanks Fibergeek and M_D for the input. I am crystal on pore temp relevance, just hazy sometimes on organizing thoughts and conveying what I want to say. I've been playing with part position in the tank until I can do something better with cooling and circulation.

    Leave a comment:


  • Fibergeek
    replied
    Spring in the mid-atlantic is cold than immediately in the mid 80's, in one day's time. Not much of a Spring.

    Like M_D says; don't get hung up on voltage measurements, it will backfire on you if you don't understand what you are looking at. Current never lies.

    R-Wells, chew on what was said for a while, you will have questions.

    I'm stepping out of this thread. You guys have everything under control.

    Leave a comment:


  • M_D
    replied
    I started the last post before I knew Fibergeek posted, I just wanted to say I will get some Ti rack tests done soon hopefully. I got so tied up I had no time to do it properly.

    Soon after I first began anodizing I noticed the phenomenon of voltage fluctuations. For instance if the power was cut, or the part lifted out of the electrolyte momentarily and then was power reapplied to the part, the voltage would go up for a while and then settle back down. Also, if I wiggled the part around while it was anodizing the voltage would go up. At first I thought it was the connection failing, which is a possibility if it isn’t good. But I knew that the connections were good, and there was another cause.

    Anyway, it is one more key to fully understanding the factors than come into play when anodizing that I’m glad to know.

    By the way, it's spring here too (at least spring like weather).

    Leave a comment:


  • R-Wells
    replied
    No M_D, it wasnt of topic at all.
    Thanks guys

    Rusty

    Leave a comment:


  • M_D
    replied
    Well that wasn't hard for you to figure out. There is a boundary layer that forms since the heat comes off the part, and even with mild agitation it is still significantly warmer on the part surface. Assuming your electrical and mechanical connections are robust and aren't hanging on by a hair, you can demonstrate how it changes by wiggling or swishing the part around and watching the voltage. Unless your tank is exceptionally well agitated, the voltage should go up immediately as the boundary cools down, and it will start to drop as soon as it begins to warm up. With LCD the temperature difference will be less between the boundary layer and general or average tank temperature, which is one of the many reasons it is well suited for hobbyists.

    This may have been slightly off topic, but I guess the point I was trying to make is that comparing voltages is tough unless all factors are controlled to the same value.

    Leave a comment:


  • Fibergeek
    replied
    You're right as usual, M_D.

    The big, fat hint I dropped several times (the temperature in the pores, not in the electrolyte is what actually counts) wasn't lost on M_D, and Sswee I suspect.

    You can see this if you study my anodization curves (1 through 3). Pore temp is obviously difficult to measure (but possible, its been done) all we can do is measure electrolyte temp. (better than nothing).

    The best case is to have the anodization curve slope unwards as the anodization progresses, I was able to achieve that with 6xxx and 1xxx alloys. 2xxx and 7xxx alloys showed a downward slope anodized under the same conditions. The closer you can get to an upward sloping curve the better, difficult with 2xxx and 7xxx alloys.

    This Spring (its Spring here now) I will start another series of controlled anodization experiments; looking deeper into cathode area and into the use of electronic feedback (a "smart rectifier") I will design to automatically correct down sloping anodization curves. I will look at Ti racking effects in more detail too.

    (edited for spelling)

    Leave a comment:


  • R-Wells
    replied
    Hi ,
    I didnt finish the last post, I had to go take my pants off, a spyder crawled up my leg

    I did notice a volatge increase when ading more air to my circulation,
    So I have to believe it is from moving the hot electrolye away from the part.

    Rusty

    Leave a comment:


  • R-Wells
    replied
    Hi M_D,
    My lillte brain says that temp has to be higher on the surface of the parts,
    At the moment I am playing with everything, trying to learn.
    I am using air to circulate, I started of with aqaurium pumps, now I am using shop air .
    I am wondering if there is not a way to eliminate all or most of the variables you mentioned.
    For instance, could we measure the resitance across the electrolye at a given temp.

    Rusty

    Leave a comment:


  • M_D
    replied
    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.

    Leave a comment:


  • R-Wells
    replied
    I cant really say, since I dont really know what peak voltage would have been for sure.
    At 90 minutes I was at 11.3 volts.
    The parts I did Monday I ran for 120 minutes peaked at 11.5v. and decreased to 11.4

    Thanks
    Rusty

    Leave a comment:


  • sswee
    replied
    How much below peak voltage was it? And what temp was the tank?

    Leave a comment:


  • R-Wells
    replied
    Hi sswee
    I understand about the variables.
    I am not really having a problem, just just curios.
    Yesterday I did 4 parts, 4.5asf for 90 minutes, none of which ever reached peak voltage..
    Thanks
    Rusty

    Leave a comment:

Working...
X