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Old 17th March 2013, 15:12   #1
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Default Electrical short circuit in an accident?

A thought came to my mind and I though I would clarify it here:

When a car (or mobike) gets in an accident, what causes the engine and electronics to shut down? If the answer is nothing then what prevents an electrical short circuit from happening from damaged wires and components?
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Old 17th March 2013, 16:53   #2
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Default re: Electrical short circuit in an accident?

It depends on the design a lot. Usually for carburetted motorcycles, the fueling gets disturbed and the engine shuts down. Nothing at all happens to the electronics.
For a car, it varies- some cars simply have a fuel shut-off switch that kills power to the fuel pump automatically. Others may have more advanced methods. But usually they are quite unnecessary to prevent a fire from an electrical short- the fuses next to the battery take care of it.
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Old 17th March 2013, 19:21   #3
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Default re: Electrical short circuit in an accident?

Quote:
Originally Posted by vina View Post
A thought came to my mind and I though I would clarify it here:

When a car (or mobike) gets in an accident, what causes the engine and electronics to shut down? If the answer is nothing then what prevents an electrical short circuit from happening from damaged wires and components?

The Fuel Supply is cut off by the Inertia Switch and the shorts are protected by fuses. Simple and easy always works in these situations
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Old 17th March 2013, 22:47   #4
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Default re: Electrical short circuit in an accident?

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Originally Posted by vina View Post
what prevents an electrical short circuit from happening from damaged wires and components?
In theory , the conditions for short circuit (i.e. crossing/shorting of wires) can happen due to an accident,

Frontal impact can damage the fan, side impact can damage the main fusebox, , not to mention damaged headlight assembly etc.

Not only due to accidental impact, but also in case of flooding , one needs to be careful of short circuits being triggered due to exposed wiring in the engine bay.

In all such cases, the car needs to be thoroughly inspected for electrical component/wiring damage, before turning on the ignition.


This will prevent unnecessary risk of fire from a short circuit.
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Old 17th March 2013, 23:05   #5
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Default re: Electrical short circuit in an accident?

I believe one of the standard operating procedures by accident emergency management teams in US/EU is to cut and disconnect the battery cables, before beginning rescue operations in car crashes. I don't think there's any crash-activated battery/electricals cut-off (apart from the normal fuses blowing in the event of a short circuit), though fuel pump cut off happens in the event of a crash (for new-generation electrically activated fuel pumps only).

As an aside, I wonder what kind of protection against short circuits might be built into an electric vehicle like the e2o/Reva in the event of a crash.
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Old 18th March 2013, 10:38   #6
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Default re: Electrical short circuit in an accident?

2 very simple reasons:

1. It depends on the type of accident and damage. The harness is quite flexible and bends along with the deformation. Only if there is a protruding metal shard cutting into the insulation will the wires short

2. Fuses blow if there is a short circuit (these are fast blow fuses), thereby cutting off current being drawn from battery / alternator
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Old 18th March 2013, 12:38   #7
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Default re: Electrical short circuit in an accident?

Quote:
Originally Posted by SS-Traveller View Post
As an aside, I wonder what kind of protection against short circuits might be built into an electric vehicle like the e2o/Reva in the event of a crash.
Not really Samindra da.
One aspect that is worrisome is the potential for battery leaks and explosion in the event of an impact. Li-ion batteries that are favoured for electric cars, are prone to explosion - with disastrous consequences.
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