This is caused by the constant touch of OXYGEN with the ANODE which is the “plus” wire. For some reason it does not happen at the same rate in all cars, and I suspect it's various qualities of water and baking soda, as well as heat from the engine environment. However, what you should do to prolong the life of the Anode is simply to make it thicker. And make sure it's made of stainless steel grade 316L – nothing less (such as locking wire which is stainless steel of lesser grade 302/304) will survive for very long.
I'm using 0.032" which is pretty thin, however I twist two or three together, using a drill. That's in order to make it more durable AND gain better contact with the water (larger surface along the wires). You'd better twist at least that many wires (two or three) for the non-failing wire too (the Cathode). Let me explain why. As I said, the only wire that fails is the Anode due to touching Oxygen constantly. The Cathode (minus) does not suffer because that's where the Hydrogen comes out and Hydrogen does not attack stainless steel. However, we want a better contact THERE, to allow better Hydrogen production at the Cathode.
I hope this is clear enough. Bottom line is: you'd better double or triple the wire for both. Stainless steel 316L will be soft enough to twist triple 0.032" wires and still be able to handle it by hand, so you may choose to use 316L for both Anode and Cathode.
At one time, for the anode I use stainless steel 316L, and the cathode 302/304 stainless steel. Now, I am using 316L for both.
Initially, the difference was for cost reasons, the cathode would be cheaper that way. If you want to use same material like I do, use 316L for all wires. I've been using 2 strands (actually one folded in half) of 316L for both electrodes. After a couple months, I'd switch the polarity to even out the corrosion - like rotating your tires. This trick will extend the life span of the Electrolyzer, before you have to rewire the towers. This is important especially with multi-cell systems, and easy to do.
Again, the anode (plus) gets corroded faster due to the oxygen surrounding it. The cathode (minus) does not suffer nearly as much because the hydrogen surrounding it does not attack the steel.
Please INSIST on 316L - the L indicates "low carbon" - which what we want. Avoid 316Lsi. The "si" means silicon, which makes this grade brittle and very hard to bend by hand. Trust me, your hands will suffer if you use this grade.
Bottom line: make an effort to get the 316L even if you have to wait a few days for a special order (that's what I did with www.SunsetWire.com) Phone orders only, 888-285-3919.
McMaster-Carr (www.mcmaster.com ) is another source for 316L, also located in Southern California. Their phone number is 562-463-4277. McMaster-Carr are not as cheap as Sunset Wire but are very organized. When you visit their website just search for "316L" and it will lead you through the options.
Personally I would not buy 316L from shady sources. They may claim it to be a true 316L but you don't have the facilities to verify that. Below is an important article on affordable alternatives to 316L, which are NOT stainless steel at all.
The cathode does not have a problem and can stay 302/304 stainless steel, because that's where the hydrogen is generated and hydrogen does not attack the steel. It's the anode that gets corroded - by the constant proximity of oxygen - and should therefore be protected. Usually we do it by using Stainless Steel of grade 316L for the anode, or even for BOTH anode and cathode because after a length of time the user can switch between plus-minus voltage terminals – thus switching the newly untouched cathode to be the the new anode.
However, some exotic metals are far better for the anode (in which case you can use 302/304 - or 316L if you want - for the cathode). Platinum, for example, is one of the 'noble' or precious metals which are excellent catalyst materials. Platinum is conductive, chemically stable and highly resistant to oxidation and corrosion. Being highly conductive and having a low consumption rate (low corrosion), Platinum makes an excellent anode material. Platinum is too expensive to be used by itself, therefore it is made affordable by electroplating a thin layer of Platinum over a high corrosion resistance substrate such as Titanium, Niobium or Tantalum.
High stability and corrosion resistance are especially important if you're going to use the Electrolyzer in a hard-to reach location, or to boost a stationary generator or marine engine that works practically 24 hours a day.
Here are several alternative ANODE METALS, recommended by corrosion protection expert Robert Foreman (thanks, Robert) which were calculated to last for many years:
Platinized Niobium is also available from other sources worldwide, in case you wanted to go into large scale production and you needed to do more homework on that. You can search Google for "platinized niobium wire anode" - try with and without the quote marks.
These are actually Copper wires, covered with a thick layer (almost 20% of the diameter) of Niobium and then plated again with a thin layer (less than 1% of the diameter) of Platinum on the outside. The wires I've seen come in outside diameter of 0.063 inch (1.6 mm) which is pretty thick so you don't need to double them. Actually you should NOT twist them, because twisting may damage the integrity of the Niobium and Platinum layers.
Since the core material is copper, they shouldn't be too hard to bend by hand. For best results select the wire type with thicker Platinum coating, when available.
I DO NOT HAVE SPECIFIC SOURCES FOR PLATINIZED NIOBIUM other than the above mentioned Fiarfield Orthodontics in the USA – you are welcome to research the international sources below. Watch out for shipping costs and delivery times. They all offer platinized niobium anodes or anode material (after checking a link, hit the back button to return to this document):