Alternator control: Fuel cut above a certain voltage

[staudt]

A few months ago the voltage regulator of my alternator died which resulted that the alternator generated 20Volt to the complete car. I will list the damage:

- MS3 module completely blown (replaced without costs by Dimitris )
- 10 fuses blown
- All indicator light blown
- All ignition coils blown
- Battery damaged
- ABS control computer blown
- ABS speedsensor blown
- Water temp sensor damaged
- Fuelpump damaged
- Complete airbag system damaged

Took me 4 months to repair everything, I don't even one to talk about the money...

Is there a way to trigger a fuelcut above let's say 16Volts. Could this be implemented in the firmware or is there an other way with a script?
With the suplied new MS3 module I do have alternator control but I'm missing a fuel cut option above a certain voltage.

[elaw]

Requests like this come along from time to time, where someone will want the engine stopped if some condition is met, like overheating.

The problem is that as bad as the problems you experienced were, if the engine had unexpectedly stopped while you were pulling out into traffic the consequences could have been much worse... you could have had an accident. That's why the developers are usually unwilling to implement such features.

There is one thing you can do though (with an MS3, not sure about other variants): hook up a "check-engine light". Then you can trigger the CEL when the voltage is too high or too low, or from a bunch of other conditions.

[TheSilverBuick]

There is one thing you can do though (with an MS3, not sure about other variants): hook up a "check-engine light". Then you can trigger the CEL when the voltage is too high or too low, or from a bunch of other conditions.

I've hooked one of the outputs up to an idiot light on my car for the voltage. If it's below 12.5v or above 15v it comes on.

[staudt]

Indeed, safety is a risk here. I was a bit biased because a lot of fuelcut options are already present in the firmware, but these are able to recover becuase of over-rev or over-boost. Over voltage fuelcut will probably always result in a complete engine stop (becuase a idling engine engine will also output 20volt on the alternator).

I have already a battery light that wil light that wil light 1Volt obove and onder target voltage.

[DaveEFI]

Snag as I see it would be by the time it has decided the volts are too high and shuts off the fuel supply, damage may already have been done. Bit like a normal wire fuse - it's often said the job of electronics is to protect the fuse.

It would certainly be possible to include a crowbar circuit to protect the actual MS, though.

[staudt]

Hmmm, but on the other hand: If I'm pulling out in to traffic and my alternator put out 20Voltage my engine will die also because of the MS3 that will burn out. So maybe a overvoltage fuelcut is not that of a safety risk...