Interpretation Of Diagnosis On-Board Electrical System Data - SN00.30-P-0001-04S
Model all (CAR)
Analysis via XENTRY
XENTRY is used to analyze the data in the 48 V on-board electrical system and visualize it in detail.
The data contains information about the status of the 48 V on-board electrical system during the last 100 driving and stationary phases.
In the process, a 48 V on-board electrical system differentiates between the engine-off and driving cycles with time and date information as for the 12 V on-board electrical system.
The data is thus analyzed based on the cycles from the 12 V analysis.
In addition, the faults and information on load and temperature management are available, which are described in more detail below.
At this point, it should also be pointed out that it should be possible to jump between 12 V and 48 V within Xentry Diagnostics so that the associated data can be analyzed in the 12 V and 48 V on-board electrical systems.
Overview of the engine-off cycle in the 48 V on-board electrical system in XENTRY
The following refers to the engine-off cycle in the data record of the 48 V on-board electrical system.
To begin with, the engine-off cycle covers the time of the stationary phase as well as the kilometer reading of the vehicle in the heading.
Below that, the on-board electrical system parameters are listed for the corresponding terms with minimum, maximum and average values as well as the values during start and stop.
Unlike "Cycle Log" and "Additional Cycle Log", the errors are shown on the left-hand side.
If an error occurs, the corresponding error will be marked by a red symbol.
State of charge
SOC refers to the state of charge of an electric battery in relation to its capacity.
SOC is given as a percentage (e.g. 0% = dead, 100% = fully charged).
Battery voltage
States of charge:
- Minimum voltage: 36 V
- Nominal voltage: 44 V
- Maximum voltage: 52 V
Battery current
The limits for the battery current for charging and discharging the 48 V battery are -400 A and 334 A.
Charge balance
The charging balance indicates whether the battery was discharged or charged during the cycle.
Because the 48 V on-board electrical system is linked to the 12 V on-board electrical system, recharging from 48 V to 12 V or vice versa is possible if the respective SOC falls below the critical value (approximately 50%).
Battery temperature
The temperature has a considerable influence on the battery.
The temperature of the 48 V battery can be seen via the graphical representation in XENTRY.
Status of DC/DC converter
The DC/DC converter control unit is the central control unit for energy management in the 48 V on-board electrical system.
The DC/DC converter has three different modes, as follows:
- Firstly, there is buck mode
, for reducing the voltage from its input (supply) to its output (load) while the current is increased.
That means that in buck mode, the input voltage is reduced to drive a load that requires a low voltage (48 V → 12 V).
- Secondly, there is boost mode
. With this, the voltage is raised from its input to its output while the current is reduced.
More specifically, boost mode increases the input voltage (battery voltage) to a level sufficient to drive a load to the desired current level (12 V - 48 V).
- Thirdly, standby mode indicates that there is no exchange taking place between the two on-board electrical systems.
Fault in engine-off cycle
The faults in the control unit caused by malfunctions on the on-board electrical system are normally difficult to reset.
XENTRY offers the option of marking the corresponding faults in red if they have occurred.
Overcurrent/short circuit
The lithium-ion battery (LIB) detects the overcurrent and disconnects the electric circuit of the 48 V on-board electrical system.
Collective fault 1
LIB48 collective fault 1 is active in the parking cycle and is detected by the DC/DC converter.
There are several errors behind this display.
Communication fault
This fault is recorded if LIN communication between the DC/DC converter and the battery is interrupted.
Switch error
If the switch module has an error and the switch can no longer be opened, this fault will be recorded.
12 V battery disconnect switch open
The battery disconnect switch is used as an emergency switch as a safety precaution.
For this reason, the 48 V battery will be fully de-energized after an accident in order to minimize the existing risk of short circuit and fire.
However, the 12 V on-board electrical system will remain energized in this case to enable, for example, the hazard warning flasher (post-crash requirements).
12 V recharging blocked
If the 12 V on-board electrical system module determines that the SOC of the battery is less than 25%, it will send a signal to the 48 V on-board electrical system module.
The 48 V on-board electrical system module will then switch to "Only DC/DC converter supplied with 48 V" mode.
The 12 V battery will therefore be recharged from the 48 V on-board electrical system via the DC/DC converter.
Recharging will end when the 48 V on-board electrical system module commands the DC/DC converter to enter "OFF" mode.
If this process does not work, 12 V recharging will be blocked.
48 V deep discharge protection
Deep discharging causes irreversible damage to the battery.
The deep discharge protection system is intended to prevent significant battery discharging in the idle phase.
The aim of this function is to safeguard the starting capability of the vehicle over an extended period.
Overview of the driving cycle in the 48 V on-board electrical system in XENTRY
The arrow buttons can be used to check the detailed view of a data record for the driving cycle. The heading shows the time and kilometer reading of the vehicle.
As in the engine-off cycle, the on-board electrical system parameters are shown in a diagram. The faults in the respective cycle are shown in red in the window on the right-hand side.
The state of charge, battery voltage and battery current show the same properties during the driving cycle as in the engine-off cycle.
Internal resistance of battery
There are currently no specified limits for the internal resistance of the 48 V battery, as the values are not constant but are dependent on materials, temperature, charge/discharge status of the battery and load.
Power output limitation
An even charging balance must be ensured via the selection of the on-board electrical system consumers. However, this may not be possible under certain circumstances.
If the integrated starter alternator is no longer able to provide the required electrical output, the on-board electrical system load will be reduced by means of consumers in the 48 V on-board electrical system being switched back.
This serves to avoid any significantly negative charge balance for the 48 V battery. This in turn retains the engine's starting capability.
The consumers will be reactivated when the required electrical power to stabilize the on-board electrical system voltage is available again.
Temperature management
Because the performance of the 48 V battery depends heavily on the battery temperature, the cooling of the 48 V system must be dimensioned such that the components do not exceed the specified temperature range (operating temperature).
To ensure that the 48 V on-board electrical system reaches a good performance level as quickly as possible, the 48 V on-board electrical system battery is heated with the cooling and heating element at low temperatures during driving until a sufficiently high temperature is reached.
The battery and DC/DC converter first send the current temperature to the 48 V on-board electrical system module.
At this point, the 48 V on-board electrical system module transmits the water temperature, the battery temperature and the temperature of the DC/DC converter, as well as the current degree of actuation of the cooling and heating elements, to the temperature management system.
Next, the on-board electrical system module transmits a signal to activate the cooling and heating elements (cooling direction) as soon as the "maximum cooling" signal has been received from the thermal management system.
Furthermore, at low temperatures that impair performance, the 48 V on-board electrical system module transmits a signal to activate the cooling and heating element (heating direction) within the battery.
Fault in driving cycle
The faults in the control unit caused by malfunctions in the on-board electrical system are normally difficult to reset.
XENTRY offers the option of marking the corresponding faults in red if they have occurred.
The corresponding faults can be detected via XENTRY.
It should be noted that short circuit, overcurrent, battery fault 1 and communication errors can occur in both the engine-off and driving cycles.
Stop - see operator's manual
A battery warning message in red will appear on the display when the fault is active. This fault is considered a critical fault message.
One possible reason could be a low minimum cell voltage in the 48 V battery.
The 48 V battery may also have opened the switch during the last journey, jeopardizing the next engine start.
48 V battery - see operator's manual
48 V battery causes a yellow warning message on the display. There could be several possible reasons for this, as follows:
- Firstly, the minimum cell voltage in the 48 V battery could be too low.
- Secondly, the 48 V battery may also have opened the switch during the last journey, jeopardizing the next engine start.
- Thirdly, the DC/DC converter could be faulty or its output could be limited.
This could potentially put the 12 V supply at risk in the future.