0
\$\begingroup\$

I was wondering today what could possibly happen if a lightning strikes my van where I have a 12V battery negative connected to the chassis. Could that destroy the battery or start a fire?

In order to prevent it should I disconnect the battery negative during the storm?

Thanks

\$\endgroup\$
  • \$\begingroup\$ Battery is probably the most robust electric component connected to the chassis, let alone the electronics. \$\endgroup\$ – user3528438 Aug 10 '17 at 13:45
  • \$\begingroup\$ All cars today use the chassis as the negative pole (ground) of the electrical system. The battery is connected to the car and its internal systems forming an electrical circuit that is isolated from the rest of the world. The lightning bolt has a certain high voltage towards the earth; the battery is not connected to the earth, hence the bolt will flow 'past' the isolated circuit of the car instead of through it. No problem for the battery so far. \$\endgroup\$ – JimmyB Aug 10 '17 at 14:33
  • \$\begingroup\$ @JimmyB What about secondary electric fields generated on every wire in the car from the magnetic fields from the lightning. Magnetic fields go through everything and can only be attenuated. \$\endgroup\$ – laptop2d Aug 10 '17 at 20:21
  • \$\begingroup\$ @laptop2d That's probably the reason that sometimes vehicles' electronics do get damaged by lightning strikes, or EMPs. I think that disconnecting the battery will not do much about that. \$\endgroup\$ – JimmyB Aug 11 '17 at 7:03
2
\$\begingroup\$

The lightning can cause a fire regardless of the battery being connected. It can go through the electronics to the battery positive as well. A lightning strike on a solid car can blow electronics, fuse metal, blow out windows and start a fire in the seats or other fabric material or said electronics.

Fire risk aside, you are relatively safer in an enclosed vehicle (No soft top or convertible) during a lightning storm. Cars have been struck while in operation with no significant damage. Others have caught on fire in the cabin, not the engine bay.

Disconnecting the battery is not important.

\$\endgroup\$
1
\$\begingroup\$

Your car body (presuming that it's not a convertible) forms an effective faraday cage - hopefully you would be fine.

As alluded in other answer the tires and ecu / electronics may take a hit. The battery being connected or not is unlikely to make any difference, since the lightning will follow fastest route to ground, and the battery does not form part of that 'circuit'. SLA batteries are rock solid near enough anyway.

Of course there may be fire following the hit due to the heat, but depends on a number of factors and may or may not happen.

\$\endgroup\$
-1
\$\begingroup\$

The best solution is to park your vehicle inside a building. If that's not possible, retract your antenna and add a metal strip to ground at your exhaust. There's a good chance the lightning will direct to ground faster and protect your car

Read more here: https://weather.com/storms/tornado/news/what-happens-when-lightning-hits-car-20140625enter image description here

\$\endgroup\$
  • \$\begingroup\$ Those strips are for two basic ideas : one to help some people with car / travel sickness and the other for radio noise suppression - are they robust enough for lightning protection ? probably not... \$\endgroup\$ – Solar Mike Aug 10 '17 at 14:21
  • 1
    \$\begingroup\$ Those strips get rid of static build up on the car body from the tires and belts turning and air-flow over the car. Often a problem in dry climates where you get an appreciable shock when touching the door handle or stepping out of the vehicle. I doubt they would last long enough to do much with a lightning bolt though. \$\endgroup\$ – Trevor_G Aug 10 '17 at 14:25
  • 1
    \$\begingroup\$ It's mainly use for static discharge and does present a chance to allow lightning to discharge safely instead of arching from the wheel rim to ground. Is it 100% fool proof, I will say no. Such design I will need a cable screw to the car chassis and the other end connect to a metal rod; buried underground. However I doubt it will work if you want to drive. :) \$\endgroup\$ – Jason Han Aug 10 '17 at 14:30
  • 3
    \$\begingroup\$ Umm... this is nonsense. Lightning that hit cars most often go from the ground and up to the clouds, taking the route with least resistance. Meaning that such a device as the one you suggest will encourage lightning to hit your car, increasing the probability to get hit significantly. Also it will ensure that the car has mostly the same potential as one of the poles in the lightning strike. It would be smarter to let your car remain a Faraday cage on 4 non-conducting rubber tires. Then the isolation distance between the chassis and ground is a much harder obstacle for electricity to pass. \$\endgroup\$ – Lundin Aug 10 '17 at 14:46
  • \$\begingroup\$ You mean electron flows from ground to cloud. \$\endgroup\$ – Jason Han Aug 10 '17 at 15:26

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.