Inertia Crash Sensor Positioning

Technical discussion on converting internal combustion to electric
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Inertia Crash Sensor Positioning

Post by gttool »

In the process of finishing one of many cars and in this build the controller and motor are in the front but all the rest of the electrical components are in the rear of the car
What are peoples thoughts on fitting the inertia switch in the rear?
It will probably respond quicker in a rear impact ?
Should they actually be fitted to the center of the car ?
not something that is in the guidelines ..

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Inertia Crash Sensor Positioning

Post by weber »

I can't see how it would matter whether it was front, rear, left or right. The main thing is that it should be mounted on something that's solidly coupled to the chassis, and I suppose it should be accessible so it can be reset (although hopefully the need doesn't arise too often Image ).
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Inertia Crash Sensor Positioning

Post by acmotor »

By inertial crash sensor for EV electrics (HAZV shutdown) I guess you mean a ~10 g type that often includes rollover / inverted vehicle tripping.
These are often ? passive mechanical switch type (ball bearing etc) and response time is not intended to be fast (10's or 100's of ms at least and g level relatively low so location WRT crash point is not a topic). They are usually non directional as well. here's one

I agree that it could be placed anywhere solid mounted and towards centre of vehicle is good as you don't want false triggers from a wheel hitting a pothole etc.
I opted for centre, upper firewall though behind rear seat or central on the floor pan would also be fine. As weber noted, somewhere solid.

The higher g (50?) sensors that operate in <1ms that trigger airbags / seatbelt tensioners are usually directional and their location is best as far toward the source of impact as possible (as time is an issue) whilst still on a substantial part of the vehicle structure. e.g. drivers side air bag sensor located on 'chassis' rail near radiator and directional to impact from front.
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