Basically: I was tired of getting electric shocks when getting out of my van.
I found some interesting stuff while looking for a solution. Scroll down to the pictures if you want to see what I ended up doing about it.
My Research and Theories
A lot of my knowledge on this comes from answers to a question I asked on Electronics Stack Overflow.
What NOT to do: the antistatic strips that hang from the vehicle on the road were actually banned from being marketed because they don’t actually achieve anything. If the vehicle was what stored the static electric charge, then the strip would be useful, since they do actually conduct. But it isn’t, so they aren’t. The reason is that vehicle tires do actually conduct enough to dissipate the charge from the vehicle to the ground. Not only do they have metal wire embedded in the rubber, but the rubber itself is partly composed of “carbon black” which is slightly conductive, but more than enough to discharge static to the ground.
So in short, the vehicle can be assumed to be at ground voltage/potential. I imagine other factors like air humidity and large surface area add to this conductivity between the vehicle and ground.
So where is the static stored? It’s stored in you. Where does the static come from? Most likely the friction between you and your seat. I still have research to do on this, but I’m satisfied that this is the source. Some of my reasoning is below:
I only get shocks when exiting the vehicle. At no point, while inside, do I get the shock. Admittedly this doesn’t explain why getting into the vehicle doesn’t result in a shock (either before or after brushing on the seat), but I don’t care, because my solution works. Although this is going to be a niggling question to be answered in a post some other day.
Non-solution: If you skipped the above, note that anti-static strips that drag on the ground do NOT work.
Solution 1: This one is very simple, requires no modifications, just a few seconds’ thought when exiting the vehicle. Hold onto some metal part of the vehicle as you step out, until you are off the seat. It works because it discharges the static from you to the vehicle continuously as you slide off the seat; so the static doesn’t have a chance to build up into enough charge that would give a nasty shock. The problem is it’s not always convenient, especially if you don’t have any exposed metal frames on the inside of your vehicle’s cabin. But I’ve found that it does work most of the time. HOWEVER: it will NOT work if you only touch the frame *after* you’ve finished sliding off the seat. Since this is how we get electric shocks!
Solution 2: Spray your car seat with anti-static spray. This needs to be done periodically. I’m told it works well, but the spray isn’t that cheap. One bottle will cost more than the solution I chose below.
Solution 3: This is the one I have opted for, because I hate having to think repeatedly. (Remembering each time I get out of the car to hold onto the metal door frame). But it took some time to install. The advantage is that you can touch it even after you’ve exited the vehicle, since it will discharge your static slowly enough for you not to feel it.
As a minimum, you will need:
- A bit of metal, (a bare wire, or adhesive foil, or strip of aluminium – just about anything)
- A resistor, (electronic component) who’s resistance is roughly between 1MΩ and 5MΩ. (i.e. between 1,000,000 ohms and 5,000,000 ohms). EDIT: I sometimes still get a shock with the 1MΩ. I don’t know if I need to bump it up to 5M, or if the spark is bypassing the resistor, or if there is gunk on it (e.g. moisture/sweat) lowering it to something like 100k. I will try a 5M-10M resistor and see how it goes.
Then follow these steps to fit it:
- Physically attach the bit of metal to a convenient place you’d put your hand when getting out of the vehicle (screw, nail, glue, whatever). Just make sure it is NOT making electrical contact with the metal of the vehicle.
- Connect one end of the resistor to that bit of metal, and the other to the metal of the door frame. You can use any wire for that.
For the electrical connections in step 2, you can either solder them, or use electrical terminal blocks (the things with screws that you tighten on a wire), or just about anything you can think of that will ensure good electrical contact.
Then the fun begins: how to make it convenient when getting out of the vehicle to touch that bit of metal that is in series with the resistor. I used a combination of adhesive copper foil, and rigid copper wire. It was a lot of fun! Spent way too long on it. Looks cool though, “Bling” in a tacky way…pure style 😉
Anti-static metal strip for vehicle door trim panel
Anti-static metal strip for vehicle door trim panel
I had two areas covered by metal wire and adhesive foil strips. I had to take the interior door panels off to get behind and feed the wires through, connect them to the resistor, and connect the resistor to the van’s frame. But job done, it looks like a cross between Mr T’s neck and Frankenstein’s forehead, but hey, it works. I’m sure other you can find a prettier way of doing it.
Random facts about static electricity
I’ll share some info that fixed confusions I had while deciding how to stop getting shocks from my van. Static electricity can be confusing, since it seems to behave differently to other kinds of electricity we’re all more familiar with. Mains, batteries, and so on.
Static vs non-static
Electronics and electrical appliances and so on usually need at least two wires for the supply. For example, a mains plug needs a neutral and a live. A battery has a positive and negative terminal. Electricity will only flow when there is a connection that allows current to flow from the higher voltage (positive) to the lower voltage (negative). Like a stream of water, it will only flow if it has somewhere to go.
Static electricity on the other hand can be imagined as two pressure tanks (maybe imagine balloons) of water. If you get a static shock from something, imagine both you and that something are a balloon, one had no water and the other one was full with huge pressure. When they connect, the water will gush from the full one into the empty one, until the pressure between them has equalized. This normally happens very quickly, and can cause a spark (and pain!) My solution above makes it happen slowly.
So this explains why rubber shoes do not stop you getting a shock from your car as you get out: the electricity isn’t flowing *through* you, (e.g. via your shoes). It is just flowing from you, or to you. (Assuming your tires are the slightly conductive kind).