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Topic starter
2020-09-06 9:30 am
Hi all,
I wanted to get some advice in connection with the power supply for an electrolyser project I have recently started. (As I don't seem to be able to add images to my post?? all the pics mentioned are on this Dropbox link: https://www.dropbox.com/sh/yyxdclnizj26qb4/AAD59hMhU7Z91USUfd7lQh7Ua?dl=0 )
While the electrolyser I have constructed will later run on a tunable pulsed square wave supply, the cleansing and conditioning stages for the plates (configuration shown in pic 1) requires a more traditional DC supply of around 4-6A at 10V. To that end, I have tried a cheap off the shelf PSU and also built two more to try and get these conditions met.
The cheap purchased PSU could deliver 4A but the max voltage across the electrolyser could only reach about 2.5V. This I assumed was due to the voltage drop occurring as current passes through the electrolyser and the somewhat exaggerated performance of the PSU.
So I built a more powerful PSU based on an old Pentium 4 AXT supply, inspired by one of the DroneBot UTube videos (see pic 2), but this still demonstrated a voltage drop across the output/top of electrolyser; see pic 3. (The reason why I have to use a separate ammeter and voltmeter with this setup is that, due to the voltage drop, the inbuilt meter supply falls below the 6V it needs to operate and so I can't see the display.)
So thinking it might be due to the same issue I went a step further and built a beefier PSU based on converting an HV transformer from an old microwave to a step-down unit with rectification and smoothing (Pic 4). I built this based on the design shown in Pic 5, and where this unit should be almost current unlimited and set only by the load characteristics. Yet again, when delivering about 7A, the voltage across the electrolyzer reads about 3V.
I then tried the ideal constant voltage source for these requirements, namely a car battery, which delivered over 10A but with a voltage drop to 8V from its resting 12.6V.
So to my query: Electrolysis requires a minimum of 1.2V to start and, for good operation, I would like 2.5V for each set of plates. So in my device, I need 10V across both groups of 4 pairs of plates. Now if I have 10V from my supply with no load and am then losing volts when the current is flowing through the electrolyser, does this mean that I am no longer supplying 2.5V for each pair of plates or does the voltage drop only reflect the electrical work that has been done already and so I needn't worry about it? In other words, if I have a 10V supply and then I connect it up, is it really relevant what the resulting voltage across the electrolyser reads?
Thanks in advance.
Jules
2020-09-06 7:33 pm
You should be able to attach images now. As a new user your first post, especially one with embedded links, usually is held to be moderated.
Try attaching an image now, by either dragging and dropping into the post, or using the "Attach Files" link.
SteveG
Topic starter
2020-09-06 8:06 pm
Thanks but I can’t see how to edit my post
2020-09-07 9:30 am
Wasn't referring to the post yo had already done, but to future posts.
And at the bottom of your posts, after posting, you should see this line options:
Hope you can see the embedded photo that I just dragged and dropped onto this post after clink on the "edit" link.
SteveG
Topic starter
2020-09-07 9:54 am
I can see some of those icons but not edit or delete. From what you say they will be on future posts although I’m surprised Incant edit my first one 😳
2020-09-07 1:11 pm
Now that I have taken the time to stop and think about it, the 'Delete' ability may only be there since I am a moderator, and the 'Edit' link starts showing up after a certain number of posts, but to be honest I don't remember what that number actually is.
I guess you might find out that number as soon as you have posted more. I'll be glad to bounce responses with you if you care to try posting back and forth with me for awhile.
SteveG
Topic starter
2020-09-07 1:12 pm
Like this? 😄
2020-09-07 1:59 pm
You making your own hydrogen ?
Are you taking the voltage readings with the plates submerged, or outside the tank and dry ?
Wouldn't the liquid in the tank cause a voltage drop ?
Topic starter
2020-09-07 2:10 pm
Planning to make OxyHydrogen for brazing/welding.
Im exploring what produces the most gas including the supply system, electrolyte e.g urea instead of just water or KOH, plate separation and so on.
then will build a carbon nano particle ‘dry cell’ one and basically find the optimum set up.
Jules
Topic starter
2020-09-07 2:14 pm
yes voltage drop occurs with plates immersed in 10% KOH and passing say 7A.
The volts will drop in this scenario but I’m wondering if it matters that it has dropped in that it’s an effect after the energy has done the electrolysis and so it’s not important. If however the voltage drop interferes with the process then it is a significant factor.
2020-09-07 3:40 pm
If you stick your ohm meter leads into the tank, what reading does it give you ?
2020-09-07 4:01 pm
Are you seeing the "Edit" link yet? And you are not going to see the "Unapprove" link either!
SteveG
2020-09-07 8:35 pm
"Edit" will only appear on the posts you make, and for only for a limited amount of time. Maybe just a few hours as I recall, but I would not take any bets on that. And maybe only after a specific number of posts. Let's see if getting to 10 posts is the magic number. You were at 8 on that last one.
We probably should have taken this to the testing thread, but maybe we are almost done anyway.
SteveG
DroneBot Workshop reacted
Topic starter
2020-09-08 8:18 am
Well, I still don't have an answer to my question but maybe one isn't forthcoming.
Is the voltage drop the 'after-effect' of the electrical work being done to produce the electrolysis or instead will it interfere with the process.
For good operation, I need 2V across each pair of plates so in my plate configuration (see attached) in need 8V. If the result of the current flow through the electrolyser is the reduce the voltage across it to say 3V then at 0.75V/pair of plates, I shouldn't get any activity - and yet I get some small bubbling on all the plates.
Of interest is the fact that the resistance between the electrolyser terminals when no voltage is applied to it is 1 MOhm. When it's running then < 1 Ohm. All the ions floating around make a lot of difference.
Here is a short video of the mild gassing at 7A, 3V that at 95MB file size I have to offer via another link:
https://www.dropbox.com/s/5g0uc9cbdslod48/Second%20Cleansing%20Run.MOV?dl=0
(This link shows as a box here but doesn't seem to play)
Jules
PS I was able to edit this! 🙂
This post was modified 4 years ago 3 times by JulesP
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