Team-BHP - Is this true - ICE affects 'onboard computer' in an mpfi cars

All on-board computers use internal regulation for the (lower) voltages needed for the electronics - the input can vary from 9.x V to 16.x V without affecting functionality. Has anyone tried dhakka-start when the battery was too weak to turn the engine?

When the engine is running, the alternator keeps the +12V line voltage up and charges battery. Severe electrical loads put more mechanical loads on the engine, which one can feel in the reduction in performance of the car - not complete failure.

If your subwoofer is so powerful that it causes headlight dimming, its not very good for electronic components.
Its better to fix up your electrical system then.
Frequent fluctuations 2-3 times a second in the voltage, eg 9-14V is certainly not good for the ECU, but its not going to damage anything as car electronics are pretty solid and can take abuse. However running on low voltage can cause some errors in the CPU if it happens for a long time, so your engine may not be operating on optimum mixture etc.,

I recently got a JBL Bass Tube and JBL 4 Channel Amp and the lights flicker all over the car as low as on 5 volume... the more the volume the more the flicker of interior lights and headlights taillights etc etc

the car is a swift D

between i have noticed this problem with all maruti cars ??? i have a baleno with a sub and 4 channel amp and face the same problem there too..

wat is a solution for this problem ?? upgrading to a higher voltage battery or live with the way it is

Are such problems harmful for the car ??

Quote:

Originally Posted by tsk1979 (Post 939664)

Frequent fluctuations 2-3 times a second in the voltage, eg 9-14V is certainly not good for the ECU, but its not going to damage anything as car electronics are pretty solid and can take abuse. However running on low voltage can cause some errors in the CPU if it happens for a long time, so your engine may not be operating on optimum mixture etc.,

I was thinking, don't most microprocessors have a watchdog circuit that shuts down the microprocessor in case of irregular / low voltage? Is this not standard in all microprocessors?

Quote:

Originally Posted by tsk1979 (Post 939664)

I tend to agree with Tanveer also. It is not recommend to play the ICE which has heavy load on the car electrical for long. As it will put undue load on the same. Thats why I monitor the voltage very closely while playing loud.

Quote:

Originally Posted by gunbir (Post 939686)

I was thinking, don't most microprocessors have a watchdog circuit that shuts down the microprocessor in case of irregular / low voltage? Is this not standard in all microprocessors?

CPU normally run at very low voltage closer to 3 or 5 volts or even less. There is a reducer in there to first reduce it to such voltage and keep it stable. Since a little noise in it will corrupt the stuff up. And I seriously fear such low level are not achieved. Even if the voltage reaches this level the CPU will not shutdown it will crash.

Also the CPU in cars in not to HI-FI wala. It is a just more of a logic controller assigend to do fixed task in a closed or open circuit as per design.

Quote:

Originally Posted by bhp (Post 939682)

Get your wiring checked bro the cars are not at fault here

Quote:

Originally Posted by low_bass_makker (Post 939710)

agree:, This runs on less-than or equal to 5V. This is kind of micro controller (pre programmed control chip) not a CPU. Regulators will take input upto 7.5 V (normally 2 V more than required output).

Its output logic is used to drive other motors controls (stepper motors & various pumps) which run on 12V. There you can get degraded performance if rpm of motor falls. This is also rare possibility as alternator can handle well both - charging battery & running all electronics stuff (excluding your subs of few kW).

Not all CPUs have watchdog ciruit. In most cases the design is closed to work in a particular range.
For example the nominal operating temperature may be 25 degree C, and the normal voltage 5V
However while design the chips are made such that they can be used around -5 to 50 degree temp.
Military grade hardware is designed for even higher ranges of temperature and voltage.
High Voltage will fry your chip, no two ways around that.
Low voltage will not damage anything, but the output your chip will give will not be accurate. So you may get 2+2=5 (Note, this is utter simplification of the problem).
Now what will a subwoofer do?
Suppose your ECU board has a voltage regulator which shuts down if voltage goes below a particular level. This means your engine will shut off or you may have some misfiring.
Infact when you push start a car with a dead battery, there is voltage and thats the reason most owners manuals of ECU equipped cars say that do not push start the car unless there is no other alternative.

So subwoofer low voltage can cause data corruption, and ECU can start giving wrong parameters and data to control devices. Not a good thing at all.

This thing is valid for all input variations. Temperature, Voltage and Clock frequency.
Suppose you overclock your ECU. Unless you dip the temperature, after a certain clock frequency, the chip will start giving wrong data output.

If you are operating your car ECU in optimum temperature range(25C) there is a good change that it can tolerate more low voltage.

But why take a chance, get a bigger alternator. Your ICE should not take more than 30% of your alternator rating.
So if your alternator is 120A, your ICE should have a mean power consumption of not more than 350-500W.
Remember, when they say alternator is rated for 120A, thats the peak, not the normal amperage.
At idling speeds, alternator churns out lesser amps.

If you are going to listen to high volumes for short period of time, in that case get a bigger battery. Along with that make sure that your cars stock wiring is not taking the load, but your ICE should take load directly through a relay connected to the battery.