Measuring the car engine on/off via 12v power supply

[borut]

car power supply for engine

Hi all,

I have a task to solve. I have to measure when the cars engine turns on/off via 12v power supply.

I know that when the cars engine runs in the 12V power supply it is possible to "trace" some noise, becouse the alternator generates some additional noise.

Is there anyone who know what is it the best way to measure this? If anyone already have a working module for this kind of measuring and if it is possible to upload it, even better.

Thank you in advance.

Bye

 

[IanP]

Maybe you can look at the following facts:
(Assuming that the battery is in good condition)
- Continuous-preservation charge is ≈ 13.8 V
- After the motor is turned off, the terminal voltage will drop quickly to ≈13.2 V and then slowly to 12.6 V ..
Sensing these voltages should give you enough information on what's going on, and react accordingly ..

Regards
IanP

 

[banjo]

I am not sure what your ultimate purpose is. However, if you are dealing with only one car, then there is an easy solution. There are numerous items like the heater fan and the radio that receive switched 12V. These items are turned off when the key is turned off. Therefore, all you have to do is sense one of their power supply lines and make your decision based on that. The fuse box is often a handy place to tap into one of those circuits.

 

[nguyennam]

Hi all,

I have a task to solve. I have to measure when the cars engine turns on/off via 12v power supply.

I know that when the cars engine runs in the 12V power supply it is possible to "trace" some noise, becouse the alternator generates some additional noise.

Is there anyone who know what is it the best way to measure this? If anyone already have a working module for this kind of measuring and if it is possible to upload it, even better.

Thank you in advance.

Bye

Hi borut, I really do not understand your problem, what are you measuring? Could you say again more clearly.

In my opinion, the supply voltage here is no problem, even it comes up to 14.5 or 15V (hey guys, not 13.8V, this is the cycle using battery, not standby using) when engine runs or 12.6V when engine stops. The problem is much noise and spike are generated from ignition system when engine runs. You have to struggle with they first and mainly.

nguyennam

 

[runblade]

Battery control charge may switch on/off (13,8V/12V) during running engine. Check oil pressure signal or alternator failure signal?