LPDD2 - Communication & Deep battery protection module

  • extends battery life
  • Easy to install
  • With mini dimensions – only 2 cm
  • At an affordable price
  • Reliable and secure

Why you need LPPD2

How does it protect the battery?

In many residential buildings there is an intercom system without access control. In order to build access control to the door, power cables must be laid, which makes installation unnecessarily expensive.

BulKey BKU controllers have the ability to communicate using the power cables with the LPDD2 power supply module. If there is already an intercom installation in the building, then a cable has already been installed from the intercom control panel to the electromagnetic lock on the front door. Typically, if you want to set access control with electronic keys and be controlled by the intercom system, you will need to add an additional cable to the door (either for power or control), which will most likely be associated with braking walls and additional complication.

The innovation is that the need for an additional cable can be avoided. An LPDD2 module is installed in the intercom control panel, in which the lock control signal from the intercom system enters and transmits the cable already going to the lock. As the LPDD2 module also includes the power supply for the access control system, it has the ability to transmit (via the power wires to the BulKey BKU controller) signals related to the power supply (there is main power supply / no main power supply). It can also transmit a signal when the BKU controller will unlock a door on command from the intercom system. Due to the small size of the components in a BulKey access control system, all components can be installed in the door frame (provided for this). This way the installation can be done very quickly, easily and cheaply.

How does it protect the battery?

You know that when 12V batteries are discharged, their voltage should not fall below 9.5V. If this happens later, the battery loses many of its properties, the charge / discharge cycles are reduced and in some cases they are unusable after that. The LPDD1 module after the battery voltage and when it drops below 9.8V, the module cuts the consumption to save the life of the battery, the ulator for the next charge.

Small size

The LPDD1 module is extremely small: only 1.5 cm by 2.5 cm. Thus, it can be extremely easily connected to different systems without having to rearrange the separate modules.

Easily connects to the system

We from LESI designed the module so that its connection is intuitive and easy. With ready-made socket for direct connection to 14V power supply and cable shoes for quick connection to the battery or if it is necessary to replace it. 

The battery is constantly charged

The LPDD1 supply circuit, in addition to the consumer, also passes through the battery. So it is constantly charged. Even after the main voltage drops, when it returns, the module starts charging the battery and so it is always ready for emergencies in the absence of electricity.

Hermetically sealed and secured housing with markings

For greater convenience, the module is filled with resin on which the inputs and outputs are marked, as well as basic parameters.

Wiring diagrams


  • Input voltage – 13.3-14V DC
  • Maximum input current – 2.0A
  • Maximum current of consumers -2.0A
  • Voltage at which the consumers are switched off for protection against deep discharge of the battery – 8.6V
  • Operating temperature: -20 ° C ~ + 40 ° C
  • Operating humidity (without condensation): 25% ~ 65%
  • Current consumed by the battery after switching off the consumers.
    • Typical: 0.5mA
    • Maximum: 1.0mA