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With the solar cycle now leading to an increase in flare activity, one naturally starts to think the effects of a large solar flare heading this way.

While major flares like the Carrington Event are well described, along with the impact in NE Canada in 1989, what I have had some trouble finding is the effect of a large solar flare on modern motor vehicles. Would a large solar flare cause the batteries in a Tesla to explode? Would it destroy the electronic ignition in a Honda Accord? Would we even be able to turn on and drive a modern car (use a 2015 Honda Accord as a reference)?

I looked through some recent posts - here and here, but didn't find a good answer.

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  • $\begingroup$ Here is a source, but I'm not sure how authoritative it is integratedskillsgroup.com/2021/06/… $\endgroup$
    – James K
    Aug 29 at 19:19
  • $\begingroup$ That's a pretty good article. My follow up question is then, why not? Why wouldn't cars be affected? What sort of solar flare would be needed for cars to have problems? $\endgroup$
    – FontFamily
    Aug 29 at 19:36
  • $\begingroup$ Also, please list your answer below so that I can mark it as correct. $\endgroup$
    – FontFamily
    Aug 29 at 19:36
  • $\begingroup$ I don't have an answer. That source says that even in much more extreme emp attacks most cars just needed to be restarted. But the research wasn't done on a 2015 Accord, So in truth I don't know the answer. $\endgroup$
    – James K
    Aug 29 at 19:39
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Never drive a car which is larger than a football field during a solar storm

Otherwise, don't worry about it.

The answer to Does a geomagnetic storm visibly deflect a compass?

shows the plot below which was a very large event.

It looks like the fastest change was about 200 nT per minute or about 3 x 10-9 Tesla/second. For a 6 square meter car that's an electric field around the car's perimeter of about 20 nanovolts all the way around, inducing a minuscule current, probably below that due to galvanic effects (dissimilar metals, rain, salt, rust, dirt).

You need a big antenna to pick it up. Since the area increases faster than the perimeter, if your car were 2,000 km by 3,000 km that would be about 20,000 volts! Of course a real circuit (a continental-sized power grid) presents substantial conductivity, so you wouldn't necessarily see 20 kV lightning, but you will see blown transformers and switching stations because of the induced current overloading.

enter image description here

Source

Of course, if your car has a magnetic compass stuck to the windshield (my grandfather's car did) it might show several degrees of deflection, but that's probably buried in the errors caused by the soft-iron effects of the car's magnetic frame itself.

enter image description here

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