Mercedes-Benz W211 User manual

1
W211 Dual Battery System
W211 Dual Battery System
219 BCM (ACB-ICC) 11-29-02

2
These technical training materials are current as of the date noted on the materials, and may be revised or updated without notice. Always
check for revised or updated information.
To help avoid personal injury to you or others, and to avoid damage to the vehicle on which you are working, you must always refer to the
latest Mercedes-Benz Technical Publication and follow all pertinent instructions when testing, diagnosing or making repair.
Illustrations and descriptions in this training reference are based on preliminary information and may not correspond to the final US version
vehicles. Refer to the official introduction manual and WIS when available.
Copyright Mercedes-Benz USA, LLC, 2002
Reproduction by any means or by any information storage and retrieval system or translation in whole or part is not permitted without written
authorization from Mercedes-Benz USA, LLC or its successors.
Published by Mercedes-Benz USA, LLC
Printed in U. S.A.

3
Program Highlights
Program Highlights
• Power distribution
- pre-fuse diagram
- pre-fuse locations
• Dual battery on-board electrical system components
- systems battery
- auxiliary battery
- battery control module
- auxiliary battery relay
- cut-off relay for interruptible loads
• Dual battery functional description
- normal modes
- failure modes
- charging auxiliary battery

4
W211 Dual Battery System Function
W211 Dual Battery System Function
An auxiliary battery supplies electrical energy for a
limited time if the systems battery voltage is low.

5
Systems Battery (G1)
Systems Battery (G1)
Location: (G1) installed in trunk

6
W211 Systems Battery (G1)
W211 Systems Battery (G1)
• Systems Battery: 12V, 95 Ah, 520A (DIN)
• Absorbent Glass Mat (AGM) design, also known as Valve Regulated Lead Acid
(VRLA) type
• Function - Primary power source for all vehicle electrical systems

7
Location of Auxiliary Battery (G1/7)
Location of Auxiliary Battery (G1/7)
Auxiliary battery installed below air intake of HVAC

8
Location of Auxiliary Battery (G1/7)
Location of Auxiliary Battery (G1/7)
Shown with HVAC air intake / filter removed

9
• Auxiliary Battery: 12V, 12Ah, 170 A (DIN)
• Absorbent Glass Mat (AGM) design
• Function - Provides supplemental power if systems battery (G1) voltage is low
Auxiliary Battery (G1/7)
Auxiliary Battery (G1/7)

10
AGM / VRLA Battery Properties
AGM / VRLA Battery Properties
• Longer service life
• Improved cold starting characteristics
• Improved deep cycle performance
• No liquid acid spills or leaks
• Fast recharge time
• Completely maintenance free

11
AGM / VRLA Battery Testing
• Requires the new Midtronics MCR 717 tester and printer
• Tester measures battery conductance by inducing A/C voltage of a given frequency
and amplitude on the battery posts and monitoring the current flow in response to it
• Discard the acid density sheet, and enter test code (recorded by tester) on warranty
claim forms
• Battery replaced under warranty must have a test printout attached to the R.O.
• Detailed information about testing, and using the MCR717 can be found in WIS
SI54.10-P-0003-01

12
Front
Front Pre-fuse Pre-fuse Box Box (F32) (F32)
70
71
72 73 74 75 76 77
Location: Passenger footwell

13
Pre-fuse Box
Pre-fuse Box (F33) (F33)
F33
Location: Front of spare tire well

14
f77
Res.
40 A
f76
N22
40 A
f75
N10/11
40 A
f74
K67
40 A
f73
A7/3
50 A
f72
A7/3
150 A
f71
M4/7
150 A
f70
F32
200 A
f78
N10/1
200 A
f79
N10/2
150 A
f80
N10/1
150 A
f81
F34
5 A
f84
N82
5 A
f85
N112 and A35/11
5 A
f86
X58/1
40 A
f87
M40/1
f89
Res.
F33
G2
G1/7
-+
N82
K57/2
-+
G1
M1
Pre-fuse
Pre-fuse Power Distribution Power Distribution

15
Legend: Pre-fuse
Legend: Pre-fuse Block Power Distribution Block Power Distribution
A7/3 Traction system hydraulic unit
N112 Communication platform (CP)
A35/11 Voice recognition module (VCS)
F32 Front pre-fuse box
F33 Rear pre-fuse box
F34 Interior fuse box (left of instrument panel)
G1 Systems battery
G1/7 Auxiliary battery
G2 Alternator
K57/2 Auxiliary battery relay
K67 AIRmatic relay
N10/1 Driver signal acquisition and actuation module (SAM-D)
N10/2 Rear signal acquisition and actuation module (SAM-R)
N10/11 Passenger signal acquisition and actuation module (SAM-P)
N22 Air conditioning control module
N82 Battery control module
M1 Starter motor
M4/7 Electric suction fan with integrated control
M40/1 Pneumatic pump of dynamic seat control
X58/1 Interior socket

16
Battery Control Module
Battery Control Module (N82) (N82)
Location: Rear of spare tire well

17
Function of N82
Function of N82
1. Monitors the voltages of (G1) and (G1/7)
2. Monitors alternator voltage (terminal 61) via CAN B
3. Controls auxiliary battery relay (K57/2)
4. Controls consumer prioritization function
5. Optimizes charging of auxiliary battery (G1/7)
6. Notes emergency operation and sets fault codes
(CAN communication / DTC’s)
7. Notes emergency operation resulting in IC / MF fault message
displays

18
Auxiliary Battery Relay (K57/2)
Auxiliary Battery Relay (K57/2)
Location: Below windshield wiper cowl plastic trim
Function:
• Controlled by N82
• De-energized during normal operation (N.O.)
• Energized to recharge G1/7
• Energized if engine running and system voltage low
• Connects G1/7 to electrical consumers

19
Cut-off Relay for Interruptible Loads (K75)
Cut-off Relay for Interruptible Loads (K75)
Function:
• Controlled by N82
• De-energized during normal operation (N.C.)
• Energized during emergency operation
• Opens 30/15R to cigar lighter (R3r1), and 12V socket (X58/1) rear of center
console during emergency operation
K75
Location: LF SAM (N10/1)
K75
or

20
Normal Mode
Normal Mode
- Battery control module monitors
voltages and calculates the
condition of both batteries
- Monitors total current
consumption through common
ground
- Consumer prioritization off
- Relay K57/2 de-energized
F33
G1
G1/7
M1
G2
K57/2
30 87
F30
E
E
N82
Kl. 30
Kl. 31
F32
CAN-B
-
-
+
+
F30 Polyswitch fuse
F32 Front pre-fuse box
F33 Rear pre-fuse box
G1 Battery
G1/7 Auxiliary battery
G2 Alternator
K57/2 Auxiliary battery relay
M1 Starter
N82 Battery control module