National Luna Dual Battery System Kit with Controller


  • Dual-battery isolator (intelligent solenoid)
  • Dual battery controller (monitor)
  • Screws
  • Cable ties
  • Instruction manual
  • 3 year comprehensive warranty
  • 40' of heavy-duty silicone core cable (20' each, Black & Red)
  • In-line power fuses
  • Accessory fuse
  • Cable lugs
  • Battery terminals
Item #3405
Physical size 4.25'L x 2'W x 1'H
Weight 9 LBS
Power supply  8Vdc - 15Vdc (display range: 11.4V - 14.2V)
Low-voltage warning DC voltage below 11.4V
Over-charge warning DC voltage above 14.65V
Cable 40' 4-core cable (20' Red, 20' Black)
Power consumption 8mA (sleep mode-option) , 35mA average , 40mA max
Shipping Dims 16'L x 16'W x 4'H
Item BMS-20201/NLS355


The National Luna Intelligent Split Charging Kit is a complete turnkey Dual Battery system, that includes an Intelligent Solenoid, Dual Battery Controller, and all the necessary materials to complete the job. Battery and tray not included.

Short Version

The National Luna Intelligent Split Charging System allows you to maintain two or more batteries in your vehicle. The Intelligent Solenoid manages the charging of both of them when the vehicle is running, and isolates them when the vehicle is off. It is all automatic. You can monitor the status of the batteries, and manually override the connection from the Dual Battery Controller.

Detailed Version

The National Luna Intelligent Solenoid is the key to an automated dual battery charging system. It can be a stand alone purchase. The Dual Battery Controller is used in conjunction with the Intelligent Solenoid to monitor battery levels and provide control of the battery connection.


Wiring the dual battery system is simple. You do not modify your existing electrical system at all.

  • Connect a cable from the primary battery positive lead to the left side of the solenoid on the Intelligent Solenoid.
  • Connect a cable from the secondary battery positive lead to the right side of the Intelligent Solenoid.
  • Connect a cable from the primary battery negative lead to the secondary battery negative lead.
  • Connect the control wire from the Intelligent Solenoid to the primary battery negative lead.
  • Plug the Dual Battery Controller into the Intelligent Solenoid, and run the cable into the cab of your vehicle to a convenient spot.
  • You are done.

Intelligent Solenoid Functions

  • The Intelligent Solenoid (IS) senses an incoming voltage of greater than 13.1V when you turn on the vehicle.
  • The IS starts an internal timer for 5 minutes, keeping the full charge to the primary battery to recoup for the discharge of starting the vehicle.
  • After 5 minutes, the IS automatically closes the circuit in the solenoid, allowing current to flow to the secondary battery.
  • This connection remains closed until the IS senses a voltage of less than 12.7V across the system. This is most commonly when the vehicle is shut off. Brand new batteries can often maintain a charge above 12.7V for a while. The IS will keep the connection closed until less than 12.7V is available, then it will open the solenoid circuit isolating the batteries from one another.
  • The IS will keep the batteries isolated until it once again senses a voltage greater than 13.1V. Then it starts the timer and the whole process begins again.
  • This process is fully automated. You do not have to manually manage the charging of the second battery.

Dual Battery Controller Functions

  • Monitors the charge level of both batteries on both voltage and percentage based scales.
  • Low Voltage Audible Alarm will let you know when your battery is running low.
  • High Voltage Audible Alarm will let you know if an unsafe level of current is flowing through your system.
  • Manually override the solenoid connection for jump starting and winching.
  • Lights and alarms can be manually shut off.

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