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In some markets the car industry offers cars and 4WDs what not properly charge the batterie(s) anymore due to very strict exhaust regulations. Either the alternator is temporarily not charging or the charge voltage is reduced.

The new DBM20A can be used in 2 main applications such as 12/12V or 24V/12V InCarCharger offering 3 different battery selections with a 3 or 4 stage charge mode (bulk, absorption, float with optional equalize)

If only the DBM20A is installed, it recognizes an IGN-signal or the present charge of the alternator. With the optional installation of the Link Start Kit (DBMLSK + IBS Relay + Switch) or an IBS monitor new version 8.1, then additional functions are available such as link start, winch support, solar link or fast charge. An existing IBS Dual Battery Systems can be partly integrated. New IBS-DBS system with future version 8.1 will support all DBS functions.

Changeover to Li-Ion additional battery

As of version 2.7, during the installation of the IBS-DBM20A, the setting of the additional battery type can be changed from lead to Li-ion battery.

New functions:

  •  20A DC/DC InCarCharger
  • 3 or 4 stage charge routine (bulk, absorption, equalize, float)
  • 3 battery types to the selection (charge levels selectable by user during installation)
  • Link start with optional Link Start Kit (DBMLSK)

Applications: See schematics below

  • 12V/ 12V InCarCharger dual battery system

  • 24V/ 12V InCarCharger (for 24V 4WDs,Trucks and Military)

  • 12V/ 12V Charging system for battery in trailer

Two main configurations are available for the IGN-input (light blue)

  • IGN concted to ignition: for cars with alternators, which stop temprarely to charge. At the first charge cycle (Main) above 13.3V the DC/DC InCarCharger starts charging. Even if the alternator interrupts the charging process the DBM20A keeps charging until 11.9V on Main battery.
  • IGN not connected: suitable for all other vehicles (incl. vehicles with alternators , which reduce the charging voltage over time ) . As soon as the charging voltage of the starter battery ( Main ) exceeds 13.3V, the DC / DC InCarCharger starts and loads according to the chosen charging voltage the auxiliary battery ( AUX ) . The charging is stopped when the voltage of the starter battery ( Main) drops to 12.7V (when the vehicle engine is switched off).

During installation with the first connection of the wires red and black, the DBM20A indicates the software version and the configuration mode for the charge voltage starts. The unit offers 6 charge modes: low, low with equalize, mid, mid with equalize, high, high with equalize what can be selected in a cycle with GND (- or chassis) of the yellow Link/Prog wire. Every short GND connection switches to the next charge mode, what is indicated by the "Charge Select" LEDs. If now further charge is done, the selected combination LED will flash after 5 sec and the configuration is saved (for sample: the Mid level and equalize mode LEDs are on, this means the DBM20A charges for 14.4V and equalize is activated).

The following charging voltages are available:


charging voltage



Low mit Equalize

14,0V und 14.6V



Mid mit Equalize

14.4V und 15.0V



High mit Equalize

14.8V und 15.4V


The equalize mode protects the battery from sulfation at least after 30 days. The DBM20A monitors the charge level of the Aux battery and how often deep discharge occured.Check datasheet of used battery to decide if equalize is needed (for instance L-type batteries do not need equalize!). There are appliances what might shut down during equalize in Mid or High charge mode due to temporarly high charge voltage.

In hot climat regions we recommend to select the next lower charge mode.

Is the attached load to the Aux battery higher than max. charge current of the DBM20A, the relay (if installed) gets activated and both batteries Main and Aux are now charged from the alternator in parallel. If the heavy load on Aux is switched off, the DBM20A returns after a time delay back to DC/DC charge mode.

The robust aluminium housing with connection latches makes a simple installation possible. Electronics is protected with silicone from water. The DBM20A is to be protected during the attachment in the engine compartment from direct temperature irradiati

Application Schematics DBM20A


  • 12V / 12V InCarCharger Dual Battery System


    • 24V/ 12V InCarCharger (for 24V 4WDs,Trucks and Military)


        • 12V/ 12V Charging system for battery in trailer

          Datasheet IBS-DBM20A

          Model/Ordernumber IBS-DBM20A
          Battery System Dual
          Mounting location Engine compartment / Inside
          Output voltage max. 15.4V
          Input Voltage 6..30V
          Consumption @ 12.5V 20mA
          Charging current nom. / max. 20/23A
          Manual Battery Link yes, with Link Start Kit
          Temperature Range -20°C- +100°C
          Efficiency 95%
          Seal silicones
          Dimension 140x81x44mm
          Weight 0.55kg
          Link Start Kit (DBMLSK)
          Product display