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Anyone knows what this option does? I ask because someone wrote me that I can probably loose torque when I install a light weight battery with less amp than oem. He wrote it can be that the the cam adjusters will not work anymore correctly with less battery power. Infact of this I can loose torque.
Can anyone help me out with his knowledge?
thanks
Not sure about this car but nowadays some cars need to adapt to a new battery when you install it. I wouldnt be surprised if this is due to sensitive electronic components...perhaps timing electronics on this car...of course, im just speculating...
So, with alternator management, you run under acceleration on battery and very little on alternator. The ECU reduces/disengages the alternator amperage generation.
Under heavy acceleration, there is a heavy amperage consumption: coil packs, cam solenoids, transmission solenoids and so on.
But then you decide to install a battery that produces less amps than stock.
Now all these have less amperage availability.
To see how reduced amps affect the function of your cam adjusters, log them, it can be done in Xentry.
Will they turn the cams to ..say.. 30 degrees when commanded, or will they only reach 25? Find out...
When the car is in decel, the alternator is switched completely on, to make up and charge the battery.
A beefy battery does well with the alternator management option, as it can ride out the heavy consumption episodes and then take the charge back from the alternator, on decel.
I have ordered the LB26xx. At the moment the best lightweight batteries on the market.
https://en.liteblox.de/the-lightweight-battery-for-racing-and-motorsport/
The reason I have figured this out, is because I myself ran a lightweight battery in an alternator management car, for years, then switched to full amp OEM battery and understood my mistake:
Years ago in the Subaru community, I made a pictorial write up about how to wire the alternator management.
I knew my ECU had the option, saw the pin out and wired it to see what happens. At that time, I didn't know how alternator management worked, but I was determined to find out experimental-wise.
People in the Subaru community followed and used my write-up and documented torque gains at the dyno, they posted graphs. I couldn't get those gains, didn't understand why because at the time I didn't know how alternator management works.
The people that posted didn't have the lightweight, but I didn't make the connection.
At that time I had the Odyssey lightweight battery, which I then replaced with a slightly heavier Odyssey with 10% more Amps, still 30% below stock. It took years for me to finally put the puzzle pieces together and buy a full amperage OEM Subaru battery and .. wow instantly...
A well known tuner posted that while having a Subaru Sti on a dyno (with alternator management), he connected in parallel a heavy duty battery and saw torque increase. Neither he nor I made the connection to Alternator management.
Knowing this, when the time came to replace the battery in my C63, I chose a recent date, fresh OEM battery, decided not to cheapen one cent in this sector and subjectively thought I saw torque gains over the tired old one.
As far as the engineering explanation of exactly how the torque reduction happens:
My opinion is that not reaching the required cam advance will negatively impact the output numbers of the engine.
I have seen Active valve tuning and did this on my Subaru, it primarily produces torque, when done right.
Conversely, not being able to stick with the cam advance angle required can negatively affect the torque production of your engine.
Now that I think about it, even the injector pulsation depends on amperage. While those amperage draw is small, the speed of solenoid actuation is essential and the amperage affects how quickly a solenoid is energized.
Now, I found a way through which the cam advance can be logged in Xentry. Xentry is not known for good logging capabilities.
So I started my research and logged my cams in my C63 with the old battery.
See the log below and notice that the stock C63 is not brilliant at following the programmed/specified cam angle.
Proving exactly why this is, is a work in progress, along with many other projects. I didn't have time to re-log this with my new battery.
2012 P31 C63 Coupe Trackrat, 2019 GLE63S Coupe Beast
Great post Vladds. Can you give me your opinion on this Voltphreaks battery? I have it and not sure if I want to use it or not. Specs seem fine and this is their highest capacity model. Car sees mostly track use and occasional street use. https://www.voltphreaks.com/ssl/cata...products_id=38
If you don't have alternator management, the difference will not be that bad, but the stock battery for our cars has 95 Amp hours, this is the picture taken from my car, the dealer battery I bought, matching the VIN and everything.
If anybody wants to help, the one thing I could not find is a picture or a spec of the Lithium Ion OEM battery that Mercedes installs on the SLS optionally. I'd like to know what kind of Amp-hours that has. And I don't think it's that small...
Quick resurect, with more info.
I'm researching the battery sensor a bit more, it is linked to the alternator management, and here's a bosch article about what the battery sensor does, and you can extrapolate from it what the alternator management does in response to the data from the battery sensor.
Some highlights:
-Charge prediction
-Voltage prediction
-Battery ageing
And a quotation:
The SOC indicates how much power is available. Using the SOC, the electrical-power management system (EEM) in the main control unit regulates ancillary load to optimize battery life and fuel consumption.
End of quotation
My opinion of the consequence:
With a battery that puts out less energy, the EEM would then increase ancillary load, taking power from the engine, to account for the weaker battery.
With a battery that constantly outputs less Amps, the EEM could mistakenly conclude that this is an ageing battery and take corrective action.
06-18-2018, 03:40 PM
