[Node]

You write "setting of 14.5V -14.8V will never damage the AGM battery. The charging current will be reduced to very low values". How do you think charging current is controlled if not via lowering voltage? You would win Nobel prize if you would be able to lower current through the battery while keeping high voltage on it So please learn some basic physics first as you are confused. Yes, it will drop as battery charges, but after certain point it will just be heating the battery and heating battery will begin increasing current.

Regarding constant voltage AGM charge mode: yes, there is such. But the charge should terminate when the voltage stops increasing over time. This is not possible to monitor while battery is in a car, because voltage is always changing as electrical consumers are switched on and off.

If you keep 14.8V without current monitoring the battery will not die immediately, but it will certainly not help its health.

---

You also write:
- "the current can not exceed 0.1C": this was correct like 30 years ago. Modern batteries can easily handle 0.2C and even up to 0.35C (as stated in that picture). And even much more when battery is deeply discharged. So fast chargers are designed for modern batteries and do nothing wrong as long as they are quality ones and monitor charge current vs voltage.
- "setting greater than 14.9V will damage the AGM battery": again, depends on the temperature of the battery, this is only valid at 25°C.
- "The battery in the BSD system is charged only up to 60-80% of the capacity": yes, but only because car stops increasing voltage above 14.0V when battery is sufficiently charged. And this is not to keep it undercharged, but for the specific purpose of not to heat the battery (my educated guess).

[DNK76]

Sorry but you do not know the microprocessor chargers,
is a current limiting example you set for 20A for 90Ah
At high discharge the voltage is lowered
but after some time it is set to 14.8V and is fixed at a low charge
battery life (generally 6-8 hours) the current decreases to about 15A, 10A but always has 14.8V or less depending on the brand charger generally 14.5V to 14.8V
  And as it drops to 4A then the charger will turn off to standby mode
13.8V and so can be connected for a year, good chargers for AGM can be plugged into the car without disconnecting from the installation
I like this study and I have always connected a voltmeter

[Node]

Why I do not understand the microprocessor chargers? The process which you described is not constant voltage, but instead current limiting charger which is better design. And that does not make my other statements invalid. And that process is exactly what is shown in the picture I attached.

P.S. And you really don't want "And as it drops to 4A then the charger will turn off to standby mode" during programming, as it will cause voltage drop spike and that is exactly what kills units during programming. Not 14.8V vs 13.8V but constant voltage.

[DNK76]

No
 I have described the charger only for charging the battery,
which I studied myself,
no power supply for programming,
13.6 - 13.8 is the voltage for the battery that does not work
And work as a capacitor requires more voltage, so it is with the charger for programming with the maximum current set

read ista there writes that all chargers set to a constant voltage of 14.8V
Only older versions of E series are on 14.2V
Note that it does not have to be ideally 14.8V can be eg 14.5V
but 13.8V is too small

[Node]

I am reading ISTA documentation. It says "This battery charge mode is set at the factory on delivery of the devices and must not be changed. The set maximum voltage of 14.8 volts in battery charge mode is not to be exceeded.". Where does it say that 14.8V is CONSTANT????? It specifically says that charger SHALL be in charge mode. And 14.8V is maximum allowed but in no way a constant.

It also says "Make sure that the vehicle voltage does not drop below 13.0 volts while vehicle programming/encoding is in progress.". I usually use my 100A power supply in special programming mode with 13.5V set for programming and never ever had any problems.

[DNK76]

I see that I will not convince you
Everyone has their say that in the language that limits me,
Let others read the documents themselves decide who is right,
And I also replied to what he founded this topic why anyway
Voltage 13.8V has a low battery warning
I also used to think 2-3 hours of diagnostics voltage 13.8V and barely lit the engine
Thank you for constructive discussions

[Node]

Well, my power supply supplies 13.5V on clamps and ICOM says it sees 13.3-13.4V irrespective of when car consumes 100A or 1A. Never got low battery warning. Not on E60s, not on F10s (these cars I do most). So I wonder what source the OP has and what cables he uses.

[DNK76]

The requirements are 4.08
in terms of voltages for individual batteries

[Node]

Good, but it states, that for programming charger must be of IUoU type and that type "Once the charge current drops below 2.5A the charger MUST switch to trickle charging". And that is exactly to keep battery healthy. I'm not sure mine supply does that, so I use safe voltage always. Please do not just put the numbers here, but read (and understand) the text as well

[DNK76]

And have you seen the current consumption of 2.5A on the ignition of the kl15?
Min even in the weakest bmw it is 8A-10A after the pumps are switched off, so the charger never goes into standby mode,
Even if you turn off kl15 for 20 seconds, it will not fall,
The bus during programming never goes to sleep so the voltage is always there
even in the KL15 OFF + R position
do not understand what you read,
There is no system in the charger which tests the power consumption of the battery,
only the overall power consumption in Amperes, throughout the vehicle
battery + electrical installation
 And there's always more than 2.5A
It is only when you leave the vehicle long in the OFF position. the tension will begin to fall
and after full charge (probably long) the current drops to 2.5A and goes into mode
podtzymania


You do not know the construction and operation of chargers for AGM batteries
You will be charging the battery charger with a transformer charger.
Where voltage increases as the battery charges,


You do not understand the full work of the battery in the car,
read about the tents of electricity (physics)
The alternator does not produce direct current,
The charger also does not produce direct current.
Why the alternator must maintain a voltage higher than 13.8V with a car with a 50Ah battery
As the voltage will be 13.6V it will be uncharged
Larger 70-90Ah battery requires higher voltage than 14V
sorry for the weak english