[willisodhiambo]

For the F series 13.8V is a little too low voltage,
At one time, on a low battery I had set this voltage to turn off the ignition because of the discharge of the battery.
Increasing to 14.8V and no such problem
BMW to the F series, G recommends 14.8V (without F80 Li-ion ,14V)
Series F, G or E series with AGM, (S1CCA AUTO START STOP FUNKTION), (S1CDA BRAKE ENERGY REGENERATION)
Phase intensive battery charging, voltage from 14.6 to 14.9V (engine braking weak battery after startup)
Voltage Support Phase (Acceleration Phase or Battery Charge Less than 13.8v and above)
There are also average values of 14V-14, V voltage used depending on the outside temperature and the battery charge level
therefore, sometimes the charger may occasionally indicate a low battery or turn off the ignition,

sorry for the weak english

Infact yesterday I noticed my power maintainer gives 14.2v but ISTA shows 13.5volts!! Ill bump it up to 14.8v on the maintainer so that I have 14v or 14.2 volts while programming. Car seems ok now. Did not see battery discharge yesterday. Thanks.

[DNK76]

ICOM A2 clone lowers the voltage by 0.3V
ICOM A1 has the same voltage as the terminals are in this respect better,
Voltage drops also have an effect,
- thin long cables cause a voltage drop of about 35mm2
, weak handles in the terminals under the mask also reduce the voltage
I set the power supply to 14.8V and at the terminal I have 14.6V at high power consumption
  (60A) drops to 14V and at 100A drops to 13V

[RReader]

ICOM A2 clone lowers the voltage by 0.3V
ICOM A1 has the same voltage as the terminals are in this respect better,
Voltage drops also have an effect,
- thin long cables cause a voltage drop of about 35mm2
, weak handles in the terminals under the mask also reduce the voltage
I set the power supply to 14.8V and at the terminal I have 14.6V at high power consumption
  (60A) drops to 14V and at 100A drops to 13V

Thanks for sharing these information , may I know is there a document or note regarding that the 13.8 V is a little to low in charging battery of F-series from BMW ?

also , may I know what is your battery charger ? a constant 100A output ? that sure is powerful , thanks .


RReader

[DNK76]

ISTA/P – User documentation Page 30
Vehicle programming/encoding in service of 251
Copyright © BMW AG/ISTA/P - User documentation
Version P2.55.x / February 2015
 If the headlights cannot be switched off (e.g. daytime driving lights), make sure that the headlights are not covered (by protective covers)
 Switch off the wiper/washer system. The wipers may be actuated during vehicle programming/encoding and encoding initialisation. Make sure that the wiper can move freely
 Make a note of all stored radio and TV frequencies and destinations
 Connect up a battery charger that is currently approved by the BMW Group in the engine compartment. Only chargers recommended by BMW are to be used in order to prevent damage to vehicle electronic components. All up-to-date chargers can be found in the Aftersales Assistance Portal under: Building and Equipment Consultation > Workshop Equipment.
 F-series and E-series with "Efficient Dynamics" (optional equipment 1CC): With the "DBL1200" and "DBL1600" or "MultiCharger 1500" chargers, the battery charge mode is used for programming. 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.
 E-Series without "Efficient Dynamic": All chargers recommended by BMW, such as "DBL 430", "DBL800", "MultiCharger 750" or "MultiCharger 900" can be used. The "FSV mode with connected battery" is still used for these chargers. The maximum voltage of 14.2 volts is not to be exceeded. Possibly a charge parameter setting is necessary.
 Do not connect or disconnect the battery charger during vehicle programming/encoding. If the vehicle voltage is too low, it can cause vehicle programming/encoding to be aborted. Make sure that the vehicle voltage does not drop below 13.0 volts while vehicle programming/encoding is in progress.
 Check the cable routing. Cables routed through open windows could be damaged when the windows are automatically initialised. Do not route cables through open windows
 Switch on the ignition (terminal 15), before the ICOM vehicle interface is connected to the vehicle
 On vehicles with Comfort Access, the ID transmitter must be inserted in the ignition lock. If the ID transmitter is not inserted in the ignition lock, this could cause encoding to be aborted
 If there is no ignition lock on the model concerned, the ID transmitter must be inside the vehicle

[RReader]

Hi DNK76 ,

Thanks for taking your time and sharing the document .

Unfortunately that document only confuse me more since there's not a single word saying that 13.8 voltage is too low ( E or F-series ) , that the charging voltage should not be lower than 13 V and not to exceed 14.8 V does make sense though .

I know you have many experience in programming the BMW , but you do know that most battery manufacturer suggest the charging voltage of lead acid or AGM is 13.8 V right ? since rarely I see anyone talking about this here , I'll greatly appreciate it if more members here could share their experience so we get to see the picture clearer .

RReader

[DNK76]

You can do your own research with bmw with equipment
AGM, (S1CCA AUTO START STOP FUNKTION), (S1CDA BRAKE REGENERACJA ENERGII )
Plug the voltmeter into the lighter and study the voltage as it changes
from driving mode:
- from the battery charge level (ie not charged is the voltage in the range of 14.7 - 14.9V sometimes even 15V
As the battery is low, the voltage is below 13.8V
- from the temperature you can see the temperature is falling, and the voltage is rising
Read about BSD and ibs in ISTA
- The voltage changes depending on the motor load
 Any engine braking increases the voltage to store energy
The same sudden acceleration is to affect the least possible load on the engine, thus lower fuel consumption, then the tension decreases,
Such a BSD principle
In addition, each charger does not charge with DC, it in conjunction with the battery, straightens the current, so while charging, the battery charges the accumulated energy, so it is desirable to increase the charging voltage
and 13.8V chargers have to keep the battery charged
The loading capacity of the AGM is 14.5V dp 14.9V
All bmw chargers have a voltage setting of 14.8V
on the charger on the terminal it is 14.6V at low current
Sore for weak English

[RReader]

Thanks again for your patient , especially when English isn't your nature language , I appreciate your trying hard to explain this in here .

Battery charger is quite different than the alternator on car , they serve different purpose in reality , and when we connect the Battery charger during programming (I can't believe you'll keep engine running during IstaP programming session ) , the GND of battery charger becomes the GND of that car already , it's not the same really since lots of capacitors are located at output PC-Board side of that charger .

Nowadays most quality battery charger actually decide charging voltage automatically by itself during the charging circle so to have the battery in best capacity , this is what confuse me that BMW want the battery charger to charge the battery with 14.8V , I think what BMW want during the programming session isn't a battery charger but a DC power supply instead , but just let the battery charger decides the charging voltage should be better for the longevity of the battery , by constantly input 14.8v to a car during many hours programming may kill the battery a little every time and make the expensive AGM retired sooner than the battery manufacturer expect , just ask around , isn't that what happened nowadays ?

RReader

[DNK76]

The charger is not a DC source,
maybe 5 to 10A is the DC current needed to replace the battery after it has been completely disconnected,
Each high power charger is a pulse converter
to obtain 100A DC requires a huge amount of capacitors on the PCB,
That's why you need a battery connected to the system it is
the largest condenser.
ISTA P in fserii and G program very quickly almost all drivers
At the same time in blocks, therefore, the need for such power
Of course, with several hours of diagnostics you can reduce the voltage to 14V,
especially as ignition off most of the time,
but for programming I do not recommend
See how the voltage drops
at 30A
40A,
60A (probably about 13.8V)
80A,
100A is generally about 13V on the termnal in the car,
I often check,
plug and turn on everything and check the voltage as it falls,
The charger set to 14.8 gives you 14.4V - 14.6V at 10-15A
Ignition ON with very well equipped series 5, 7 needs ignition of about 20A-30A and it gives 14.3V
fall depends on the terminal construction in bmw and cables in the charger, terminals,
therefore, different chargers are different,
It would be dangerous to have the charger hold 14.8V at the terminal in the car, as the alternator does, keeping the voltage constant required by the BSD system.
Only if the ignition switched off will increase to 14.5V -14.7V depending on the battery charge

[Node]

DNK76, yes, ISTA documentation suggests using 14,8V BUT on CHARGE mode. Charge mode monitors current, and when current drops below specific limit, it drops voltage automatically. Like in attached picture. If you put 14,8V without charge-current limiting and supervision, you ARE potentially KILLING the battery. Safe long term voltage as shown in the picture is 2,3V per cell so about 13,8V. I would never supply more than that in supply (not charger) mode.

Car itself (when talking about cars with S1CC and S1CD) also monitors current going into battery and will NOT increase voltage to 14,8V when battery is sufficiently charged. Cars without those options will not increase voltage above 14,0V.

P.S. These voltages are for 25°C. When battery is colder (and IBS also monitors that) the voltages are higher. Like 15,3V charge/14,4V float at 0°C. At 40°C - 14,3V/13,4V.

P.P.S. These numbers are for compatible AGM batteries. Flooded batteries and cheap AGMs (hence the question in ISTA when you are registering battery change: are you installing BMW or generic battery) are more sensitive. Hence ISTA documentation tells you to use lower voltage for E series, because they rarely have quality AGMs installed.

P.P.P.S. Regarding "100A is generally about 13V on the termnal in the car": quality automotive chargers (so all those listed in ISTA documentation) increase the voltage when current increases to have the specified voltage on the clamps. They either have cable calibration mode when you short circuit positive and negative clamps so they can measure cable resistance or that is hard programmed into them.

[DNK76]

Charging the AGM battery
constant tension
U = 14.5V to 14.8V maximum starting current 0.25 C (battery capacity) 20 hours
and 4 hours 0.025C (battery capacity)
90AH x025 = 22.5A
The problem is charging the battery with a constant current without voltage limitation in the so-called fast chargers the current can not exceed 0.1C,
setting greater than 14.9V will damage the AGM battery
The battery in the BSD system is charged only up to 60-80% of the capacity
because they have to take charge of the energy when charging, with the system of energy recovery from braking, please read ist,
setting of 14.5V -14.8V will never damage the AGM battery
The charging current will be reduced to very low values
I've seen a current of about 2A with ignition off on a weak battery and never before connected probably the charger for programming maybe at ASO,
Generally, diagnostics and programming do not take more than 3-5 hours
13.6V-13.8V is the limit voltage only for voltage sustain
With a low battery, you may see a low battery warning message and turn off the KL15 which happened to me at 13.8V,
The instruction states that the charger must not be connected to the extreme discharge
battery,
As a rechargeable battery, it is not possible to charge more than 0.25C of battery capacity
As for the usual battery it writes to not exceed 14.2V