The Rover-Landers of BC

I was intrigued to read in the Rover-Lander issue that just arrived that an AA patrolman was able to start a balky Series L-R by using a potato as condenser.
Now I am a gullible sort of chap, so I am impressed by ingenuity and baffled by electrics, so I was prepared to believe the story, until I realized my Rover-Lander arrived the day after April Fool's Day.
Now this is not to suggest our Dear Editor would seek to fool anyone so dumb that he burned up the wiring in his Series 3 because he neglected to disconnect the battery before delving into the innards.
So, can someone explain in simple words how and why a potato can function as a condenser. Perhaps a starting point might be to explain what a condenser does.
Keep it simple, please.
Larry Eric

Apparently it is an old wive's tale that has been around for years. It is up for debate if it actually works.

No way a potato would work as a capacitor/condensor, but it could function as a ballast resistor.

I did a quick search on the internet.

A 'condenser' is an archaic term for a capacitor. (A capacitor holds a charge like a mini-battery.)

So, a potato, eh? Go to any kids' science fair and you're likely to see a 'potato clock' (a small digital clock plugged into a potato). (GEEKY CHEMISTRY WARNING HERE!) It works because the potato provides a weak acidic solution to transfer charges between two DIFFERENT metals (copper and zinc are the usual favourites). This is exactly the same as the battery acid in your car battery that sloshes around between two metal plates (usually one being lead in a 'lead/acid' battery). You have six of these 'cells' to make your 12V battery. (You don't let the kids play with lead as it's rather poisonous!)

Will this start your car? I seriously doubt it! A potato battery has a very low voltage and a miniscule amperage. But there's one possibility: let's say you need to start your car (basic petrol Land Rover with NO computer thingies at all) and your battery is COMPLETELY dead (or even missing). In that case, a bump-start may not work because, as you get the motion of the car to turn the engine and the alternator, there isn't any power to energize the electromagnets in the alternator in order to generate a current (spark) as it spins. A potato MAY provide the small, small current necessary to give the alternator's electromagnets just enough to generate a magnetic field. This would then cause a massively positive feedback loop to get the alternator going and then, hopefully, your car.

Thinking some more, you can definitely start a new, modern, high-tech Land Rover (e.g. L405) with a potato. A potato could theoretically provide enough power to make a VERY short call on your mobile phone to JLR Roadside Assistance. Then JLRRA will start your car. :mrgreen:

Well, you DID ask... :wink: :wink:

And it looks like swamijake swooped in with the one-line answer while I was writing. :mi5:

You need to first understand the purpose of the condenser in the ignition. http://classicmechanic.blogspot.ca/2011 ... n.html?m=1

The idea is the potato dampens the voltage spike enough to allow the points to break cleanly.