electrolytic rust removal

[droopsnoot]

One point about whether to remove paint that someone asked about a couple of pages ago, obviously you do have to remove a bit of the paint to give the connection to the charger a decent chance of conducting. Obvious, I know, but I don't think it was said. Other than that, a lot of paint will lift, depending on how good it was to start with. Another thing you can do to make an intelligent battery charger work is to wire a car battery in parallel with the setup, so the charger is seeing a load and may not cut out.

 

[Screwdriver]

Electrolysis will work underneath the paint so long as any part of the piece is electrically connected, so you just need one good spot. In practice, it does help to expose the surface if there are large sections of thick paint because the effect will be more noticeable on exposed parts if you have to leave it in for a long time.

Connecting a battery to the system (as if you were charging it at the same time) rectifies the crude DC output of a typical charger, smoothing out any AC ripples that would otherwise interfere with the electrolysis process. For example if you were to use AC in the process, you will get entirely different results and some chemical reactions that don't even bear thinking about!

S.

 

[GW8IZR]

Just need to be a little bit careful connecting a battery as suggested, the energy from most chargers is limited whereas you can briefly drag many thousands of amps from a battery.

 

[Screwdriver]

very true...

 

[MattF]

A simple filament bulb inline is usually the best means of introducing a load, if needed. It also has the plus point of being a visual indicator of current flow.

 

[droopsnoot]

Oh right, good point. As was commented earlier up, this was something I'd read on another thread about this. Thinking back, I can't say it exactly helped. I do struggle to get current flowing in my setup - to the extent that I can sometimes only tell the gauge has moved by flicking the mains off for a second to see it move. So maybe a bulb will help more than a battery.

Out of interest, how would you drag many thousands of amps out of a standard car battery? Or is that where the "very briefly" comes in? Sure this was probably covered in Physics, but it's a while back now.

 

[MattF]

By shorting it. Several hundred would probably be a more realistic figure, but if you happened to short something with a battery connected, you could quite easily spot weld those parts together due to the battery, and then something would likely melt before the battery quickly exhausted itself. Just running from a PSU, you'd either blow else trip the PSU, (which of those happens depends on how well it's designed).

 

[Screwdriver]

Oh right, good point. As was commented earlier up, this was something I'd read on another thread about this. Thinking back, I can't say it exactly helped. I do struggle to get current flowing in my setup - to the extent that I can sometimes only tell the gauge has moved by flicking the mains off for a second to see it move. So maybe a bulb will help more than a battery.

Out of interest, how would you drag many thousands of amps out of a standard car battery? Or is that where the "very briefly" comes in? Sure this was probably covered in Physics, but it's a while back now.

Depends on the battery of course but you'll get several hundred amps easily from a typical car battery. Look up "cold cranking amps". In practice, whatever wiring you're using for electrolysis is going to blow like a fuse if you short a car battery. You don't really need more than an amp, especially if you're leaving it overnight. Bulb is probably a good idea to convince you it's working. Needs to go in series of course!

S.

 

[GW8IZR]

By shorting it. Several hundred would probably be more realistic figure, but if you happened to short something with a battery connected, you could quite easily spot weld those parts together due to the battery, and then something would likely melt before the battery quickly exhausted itself. Just running from a PSU, you'd either blow else trip the PSU, (which of those happens depends on how well it's designed).

Short circuit current is many thousands of amps only limited by the internal resistance of the cells and the connection resistance to the short, Given the right load and secure connections its possible to create enough gas in the cell to cause the battery top to come off and spray acid all over the victim - of course the battery very quickly discharges and the current drops like a stone. Impressive things these wet LA cells which we take for granted as it sits benignly taking up space on the floor :-)

Many years ago we tested the sc current of a 30AH UPS battery, a bit more than a third of the size of a normal car battery and designed for deep discharge not starter current. The peak current was 1900A for 25mS which was about 600 times greater than the ten hour discharge rate.

The other thing to be very careful of is floating a battery across a regulated bench power supply, this is an old trick to get a higher peak current. If the bench supply has over voltage protection in the form of a crow bar it can simply short the output of its regulator to protect the load. The battery then dumps its energy back into said crowbar circuit and lots of smoke ensues.

its just a matter of being careful and remembering the energy stored is huge and to be respected. If you plan to use a battery as described stick a fuse between it and the charger and a fuse between the battery and the load and keep the wires apart.

 

[mike 109444]

Having followed this thread with some interest I found myself ahead of my work midweek and decided to build one for myself I had a new unused 5 gallon bucket kicking around and all the appropriate materials so set about it trying to be clever haha....... I had an ancient flange ring laying around so welded my 3 anode pieces inside evenly spaced so it all fits snugly inside the bucket with the ring on top & I was quite happy with it all, until.....
I put a scrap test piece in connect it all & power it up..... All good for a couple of mins then my battery charger cuts out!!!!! Tried a couple of Times then gave up in disgust lol So what am I doing wrong could it be the way i built it or my charger or am I missing something silly? Cheers fellas

bucket was not metal was it ???

 

[MattF]

Many years ago we tested the sc current of a 30AH UPS battery, a bit more than a third of the size of a normal car battery and designed for deep discharge not starter current. The peak current was 1900A for 25mS which was about 600 times greater than the ten hour discharge rate.

By eck, that's a fair bit. I stand corrected. Wouldn't have honestly thought it would come anywhere near that.

 

[Screwdriver]

Short circuit current is many thousands of amps only limited by the internal resistance of the cells and the connection resistance to the short

In theory yes and that is true for any lead/acid battery but in this specific application, the wiring simply wouldn't support more than a few hundred amps at which level any typical wire is going to fuse.

All I am saying is if you extrapolate the danger of using a lead/acid battery to anything, a lot of people are going to struggle to start their cars...

 

[GW8IZR]

I dont want this to turn into a bigger issue than it is, what I'm saying is be careful when hanging bits of wire off chargers and batteries.

Its not inconceivable that someone reading this thread and thinking its a good idea will think 'now how do I connect all this lot to a battery' they grab their jump leads and attach a battery to big lumps of steel splashing about in salty water..

Its not dangerous to use a SLAB to start a car using the proper fixed wiring and starter solenoids, once you start doing temporary connections using jump leads it gets more risky.. just need to be careful thats all.

And its not just theory.. :-)

 

[Richie mac]

Lol @mike 109444 No it's a plastic bucket

 

[T0rnado69]

i used a gunston charger with a plastic bucket as per post 1.
didnt have any probs..

picture of charger

though i have plans to get a power supply, still waiting for website to show stock of the new version.

 

[droopsnoot]

Thanks for the clarification. I tried to go back and edit my post in case anyone reads the bit about adding a battery and decides to do it without reading all the stuff after it, but I cannot.

 

[Screwdriver]

Its not inconceivable that someone reading this thread and thinking its a good idea will think 'now how do I connect all this lot to a battery' they grab their jump leads and attach a battery to big lumps of steel splashing about in salty water..

People like that deserve to die. Anyone who would do such a thing doesn't have long on this earth anyway.

<edit> and they're still only going to get a few hundred amps before even a jumper lead is going to fuse. To get the thousands of amps a battery can theoretically discharge in reality you need to drop a spanner over the terminals. What are you suggesting happens to this particular idiot who shorts out the parts in his dip tank while using jump leads and a massive lead acid battery?

 

[MattF]

People like that deserve to die. Anyone who would do such a thing doesn't have long on this earth anyway.

That's a bit harsh. Everyone has to learn somehow, and genuine accidents do occasionally happen. It only takes one piece to slip or such. That is the type of reason why I suggest that people take anything they read with a pinch of salt though. Sound and thorough revision is key.

 

[Screwdriver]

That's a bit harsh. Everyone has to learn somehow, and genuine accidents do occasionally happen. It only takes one piece to slip or such. That is the type of reason why I suggest that people take anything they read with a pinch of salt though. Sound and thorough revision is key.

It is an extreme response to an extreme scenario. There is a school of thought for using only a car battery because then you can leave the tub outside where any noxious fumes dissipate harmlessly. Fact is, there are many reasons for using a battery in this process and one slim and as yet inexplicably lethal scenario when you shouldn't.

S.

 

[MattF]

Actually, there are no valid reasons for connecting a battery directly, fused or otherwise. Even if a battery is the only plausible power source, then there is absolutely no reason why a protected, voltage or current regulated circuit could not be used to control the process.

With regard the point of having the vats outside, all of mine are, and I don't use a battery.