Parts and Tools

Here is a list of parts and tools involved on the current stable installations. Prices are approximate dollars USA as last seen.
Negative air ionizers.
These are electronic components, really being designed for /Pic from AliExpress.png "negative ion generators" and many air cleaners made for use in home, office, industry, and vehicle. I am tending to call them "air chargers" because that is what they do: they charge air, they give negative electrical charge to air.
There are a wide variety of these available from a large number of different sources. The ones I'm using have four output wires coming off of each, each end of which has a small carbon-fiber brush. The carbon-fiber brush approach is relatively new; previously they all used sharp metal pins for output, but these tended to self-abrade over time, even though the better ones were made out of very tough alloys like nichrome. The carbon fiber strikes me as a very good idea, likely to be much more durable.
Most of these in use right now were bought from the Alanchi Official Store on AliExpress. At this writing they're very much available, though it is important to explicitly choose the 12VDC version, there are three options (220VAC, 110VAC, 12VDC). The last time I ordered, the 12VDC version was grayed out, perhaps they were out of stock. A bit of searching found several more sellers, at least two of which were rated at "30 million particles per cm/3" like the original; here's one which I recently bought from, and another which I haven't tried yet.
It is that capacity, 30M per cm/3, which originally drew me to the Alanchi device; these are, at least according to the published specifications, the most powerful I have confirmed using 12VDC. For a few days I saw one up on AliExpress which had a published capacity of 125M per cm/3, 120VAC only, and I toyed with the idea of an inverter under the hood...but that one went away altogether very rapidly. Regardless, if you do try any variations on the theme, make sure you have appropriate business ends on the output wires. Quite a few of these elements are sold without any business ends at all, and you will need them to get results.
Eventually I hope to have hard numbers of my own testing, concerning the output rating. But this won't be for a while. Quality ionization test meters are very expensive (starting about $900, going way up). I may have a partial workaround, we will have to see how that unfolds.
The first installation is currently using twelve of these; the second, two.
$5-$8 each, plus shipping.
Fuse tap.
/Fuse Tap.png A fuse tap is something which permits us to safely and reliably add a fuse-protected circuit to a standard auto/truck electrical system. We remove an existing fuse, and plug the fuse tap into the socket. The fuse tap takes two fuses, one being the original which protects the original vehicle circuit as it did, and the second protects the new circuit, which is connected to the wire extending out of it. If the fuse tap is placed in a socket belonging to a circuit which is turned on only after the ignition switch is turned, the device on the new circuit will turn on with the engine, which is very nice, because then we don't have to flip an extra switch to turn on our widgeteria!
Most if not all auto parts stores have these, they are very commonly used for major stereo installs and other setups. The only catch I ran into, was the amperage: local auto parts stores had only 10-amp-maximum fuse taps, and the circuit I need to tap into is 20-amp. (There's an Ignition circuit which is 10-amp, but I have encountered advice a-plenty saying not to use that one.) So I found this one on Amazon, fitting the vehicle, 20-amp, and most satisfactory.
$9 for a pair.
16-gauge stranded automotive insulated hook-up wire.
Red, black, and maybe white.
I'm not sure anyone calls it "hook-up wire" anymore, /red-wire.jpg but they used to, so I'll keep it :-) Available at any auto parts store, also called "primary wire" for some reason; I have no idea what "secondary wire" might be! Red and black for connections to positive and ground; white for sensors or timers, i.e., the very experimental. A basic installation just needs red and black, in order that we help prevent ourselves from wiring backwards, which would be very unhelpful indeed.
Needs depend on the vehicle and how far away the air filter cover is from the engine compartment fuse box. As a minimum, best to figure on one 15' run and perhaps 7' more or less in smaller bits. Experimentation is different of course. Do get this from an automotive source, we want to make sure the insulation will stand up to the outdoors and a hot engine compartment.
From one source, $8 for one 30-ft roll, $19 for a 100-ft.
Wire Stripper with Crimper.
/wire-stripper-4big-cropped-adjusted.jpg /wire-stripper-4small-folded-cropped-adjusted.jpg /wire-stripper-4small-stretched-cropped-bright.jpg This class of tool is used to cut wire, strip the insulation from the end, and crimp items onto the bare ends thus made.
I have been using two different kinds of these, the one on the left for the 16-gauge wire used to run around the engine compartment, and the one on the right (it's a double plier, one side crimps, one side does the rest) for the much smaller 12VDC input wires, probably 20 gauge, built onto the Alanchi air charger units. I am fairly confident that someone has made one tool which can efficiently strip both sizes, but the two I have are good for just one or the other. There is quite a variety of these tools out there. There are expensive ones which do not work well, do be careful. Local retail is probably best so you can test easily. You do want them made of good metal, with a strong durable pivot.
Mine are about $15 each.
Lever nut connectors.
These are a fairly new invention, very useful for connecting wires.  Originally I
/lever-nut-wire-connectors.jpgused a large number of electrical disconnects (see next item) to make a kind of little web of wire, to connect everything together.  But this was not very neat, and very not easy to handle, not easy to add, subtract, or rearrange.  The biggest problem was, we're talking about connecting four, five, six, and more wires together, and the methods in common use just don't adapt to this.  Eventually, some friends on TorqueCars had some suggestions, and I learned about Lever Nuts.  There are many companies making them now. 
/lever-nut-2nd-version-wire-connectors.jpgThis second kind (lower picture, probably to the left of this text) wasn't available when I bought my current set of ones like the picture above, but their shape is more convenient in some ways.
About $15 for a nice big set.
Electrical disconnects, 16-14 gauge.
These are little bits that go on ends of wires. They are plugs and sockets. The
"female" of this sort also slides right onto the terminals of a wide variety of switches and relays, including the timer relay being used for testing right now.
These things crimp on, meaning they grip the metal of wire ends by having innards bent inward, using a crimper tool. They are use-once: if you crimp badly or need to make a change, you cut these off the wire and crimp on another.
The right stripper/crimper will do both jobs nicely. I am told that for automotive/vehicular electrical connections, crimping much better than solder, because it is much more vibration-resistant. They have also done work with the metallurgy, so corrosion is not an issue, even though the wire is copper and the metal of the disconnect is different. One warning: you can buy these from hardware stores, but hardware-store disconnects do not always interoperate with auto parts store disconnects, the shapes are just slightly different.
I started out using a lot of these things, building up a web of wire over time to connect all of the air charger units.  I have replaced almost all of them with lever nuts, which can be opened and closed for each wire many times, and which are designed to handle many wires coming together.
$4 for a set of five of each gender, auto parts stores.
Electrical butt connectors, 14-16 gauge, and also 10-12 gauge.
/butt-connectors-two-sizes-cropped-brighter.jpg These keep things neat when two wires need to be connected to a third, and more variations.
With twelve air charges and the timer, I have had to make a little wiring harness, and these are a big help. Every three air chargers' 12VDC positive leads get wrapped together and crimped into one of the 16-14 gauge blue variety, and then 16-gauge red wire is crimped into the other end. Keeps it all neat and reasonably easy to understand. The 10-12 gauge yellow variety is useful because, with four sets of three air chargers, I have multiple 16-gauge wires to combine the same way, and the larger works nicely for this. The result is not exactly simple, but I have not found a better method to accomplish the build as of yet.
$6 for a package of 7, auto parts stores.
Crimp-on ring terminals.
/ring-terminal.jpg We're using these right now both to secure ground wire to battery, and to secure to a handy hole in the engine compartment via a thick sheet-metal screw. Far more secure than bare wire end under a screw head! Can't always do it, but great to do when we can.
The color of the crimp matches wire size, but you may have to vary from that match, in order to get one whose ring will work with whatever screw size you have to work with.
$6 for a package of 5, auto parts stores.