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Author Topic: tune charging system to free up some HP?  (Read 7158 times)
userpike
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« on: March 17, 2013, 12:42:06 PM »

I want to know if its worth looking into making it so that the alternator only charges the battery during cruise and engine deceleration. That could free up some HP during acceleration. I know the newer Mercedes do this. Can this be done with me7.5? I don't know where to look in the FR for this type of thing.
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ddillenger
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« Reply #1 on: March 17, 2013, 12:51:22 PM »

How would you do this without a clutch on the alternator similar to what the AC compressor uses?
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Drehkraft
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« Reply #2 on: March 17, 2013, 02:22:09 PM »

How would you do this without a clutch on the alternator similar to what the AC compressor uses?

Some cars already have PWM/ECU controlled voltage regulators.   Wink
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ddillenger
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« Reply #3 on: March 17, 2013, 02:51:48 PM »

oh, I know that, but not this one. lol
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nyet
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« Reply #4 on: March 17, 2013, 02:54:26 PM »

In theory, perhaps a relay could be connected to the alternator output terminals, and wired to the AC compressor clutch cutout?
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jooo
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« Reply #5 on: March 17, 2013, 04:00:35 PM »

Stupid thing to do. If you disable alternator you will at best get slightly above 12volt to fuel pump and ign coils when these really make use of high voltage. (during high boost and rpm)
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userpike
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« Reply #6 on: March 17, 2013, 04:43:53 PM »

Stupid thing to do. If you disable alternator you will at best get slightly above 12volt to fuel pump and ign coils when these really make use of high voltage. (during high boost and rpm)


it was explained to me by my buddy ( a Benz mechanic) that it doesn't disable the alternator, just maintains enough load to power the car without adding the load of charging the battery during acceleration. during deceleration the load on the alternator to charge the battery + maintain the load required for proper function of the vehicle works as a brake to slow the car down when in gear via parasitic drag from the alternator under load.

As far as a stupid thing to do...Mercedes has already implemented this idea on their production cars.
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nyet
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« Reply #7 on: March 17, 2013, 04:46:28 PM »

Well then, a relay to the battery then?
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userpike
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« Reply #8 on: March 17, 2013, 04:49:13 PM »

Well then, a relay to the battery then?

for?
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nyet
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« Reply #9 on: March 17, 2013, 04:53:09 PM »

run the AC compressor cutout line from the ECU to a relay that disconnects the battery, or switches to rectifier circuit that only allows current to run FROM the battery into the bus.

Then the alternator will not have the extra load from charging the battery.
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jooo
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« Reply #10 on: March 17, 2013, 05:00:12 PM »

it was explained to me by my buddy ( a Benz mechanic) that it doesn't disable the alternator, just maintains enough load to power the car without adding the load of charging the battery during acceleration. during deceleration the load on the alternator to charge the battery + maintain the load required for proper function of the vehicle works as a brake to slow the car down when in gear via parasitic drag from the alternator under load.

As far as a stupid thing to do...Mercedes has already implemented this idea on their production cars.
I never said MB's solution was stupid.
Forget it and instead raise boost by 0.001 PSI :-)
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userpike
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« Reply #11 on: March 17, 2013, 11:40:49 PM »

run the AC compressor cutout line from the ECU to a relay that disconnects the battery, or switches to rectifier circuit that only allows current to run FROM the battery into the bus.

Then the alternator will not have the extra load from charging the battery.


I was thinking the voltage reg would be the "relay"

it already controls whether or not the battery gets charged.

I want to know if there is a map or something to tell the voltage reg what to do or if a function could written into the software file.

like what Drehkraft  said above.
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cerips
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« Reply #12 on: March 18, 2013, 01:21:19 PM »

Seriously, a 150A alternator running at 14V gives out 2.1KW or 2.8 HP, you really going to notice that?
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nyet
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« Reply #13 on: March 18, 2013, 01:39:56 PM »

Seriously, a 150A alternator running at 14V gives out 2.1KW or 2.8 HP, you really going to notice that?

In a N/A motor, yup Smiley

but yea, in boosted applications, doesn't seem like much.
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ME7.1 tuning guide (READ FIRST)
ECUx Plot
ME7Sum checksum checker/corrrector for ME7.x

Please do not ask me for tunes. I'm here to help people make their own.

Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your experience.
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