CaliBenzDriver

The old 14.2V regulation was perfect for the engine and the battery life span!

The more complex 12.6V float-voltage control system doesn't save significant amount of gas to make up for its complexity.
A fully charged battery under 14.4V uses the same current load as under 12.6V... zero amp, no load.

Anyway this complexity is here to stay:

• 14.9V deceleration high-charge
• 14.4V bulk charge rate
• 13.7V absorption rate
• 12.6V float rate

.
Above numbers are all perfectly good voltages associated with the different battery charge level.

Any deeping below 12.3V is a disfunction that drain while-driving extreme conditions.

pierrejoliat

Your 220 does not have smart charging, your 212 does, it's a complicated system, but usually only charges your battery to 80% or so.There's an encyclopedia on how it works

Yes Cali, I should have identified the author of the encyclopedia, LOL

CaliBenzDriver

These Mercedes are built very carefully. Let's factor out the exhausted battery chaos with a few details.

-- The ECU quickly bulk charges MAIN Batt to 80% with burst of 14.9V

-- then all the way to 100% fully charged with normal legacy style voltage 14.4V, 13.7V the way it used to be without smart charging.

-- then 12.6V float voltage to hold charge while supplying 100% of every electrical loads.

Great! All of that is the perfect way it's supposed to work.
However battery and chassis power are wired to help disrupt modules with noisy power.

> POOR ENGINE - CHASSIS STRAP:
While in this topic, you get to understand how there can be two strong power sources:
ALT (engine) and the Batt (chassis).

When the single chassis strap is oxidized by road projections the chassis load can no longer see ALT as a source and only see BATT as source.
OMG... BAD NEWS!

You may be reading this thinking what do I care?? Keep it in the back of your memory somewhere!

Personally I remember Master Surya at some point dealing with his GND with fat *** cables... but did not hit home why I would be doing that later myself.
Rule No1: everything Master Surya touches in depth is Golden. I really think we need an Index

WHY: the oxidized strap offer enough drop voltage under load to make the battery become a better supplier over ALT minus dropped voltage caused by our favorite poor GND strap.
If you are dealing with marginal battery performance... Install a SECONDARY GND STRAP!
It is cheap easy way to sanitize weird power glitches and tired batteries issues. No code

> BATT SENSOR:
-- The battery negative terminal has a smart sensor that measures the battery internal heat in addition to voltage and current.

-- The temperature is used to slow down charging rate in case the battery is overheating. Legacy charge circuit used to not have this data.