By Grant Spolander

Back in 2018, National Luna launched a new battery-box option that their customers nicknamed : ‘The Black Box’. The product featured a patented faceplate design that was a big leap forward from their original Portable Power Pack (Aka: The Grey Box) where the plug points are mounted on the side of the unit.

The Black Box’s stepped layout allowed National Luna to mount a larger number of output and input power points. What’s more, because the plug ports are positioned at the front of the box, it makes them easier to access.

The design must’ve been a big success, because a short while later the South African company launched several more battery box options. This included their taller Blue Box, the 25A DC-DC Green Box, and more recently, their flagship 40A DC-DC Green Box with a distinguishable black lid.

With the exception of the original Grey Box, all four battery-box solutions feature the new stepped faceplate design. However, after heeding to their customers calls, they recently redesigned their Grey Box system so that the Gen 2 model utilises the same stepped faceplate layout.

They also added Bluetooth connectivity to the unit – compatible with the NL Connect app – as well as a dual-battery display that shows:

  • Battery voltage
  • Input charge current
  • Output load current


The Bluetooth app is available for both Apple and Android devices; it’s quick to download and easy to navigate. Use the serial number on the side of the box as the password when connecting to the Portable Power Pack.

Because the Grey Box uses a split-charging system that can be connected to your vehicle’s alternator, the box and the app both display the voltage of your vehicle’s main cranking battery, as well as the auxiliary battery’s voltage in the box itself.

The app will also tell you if the auxiliary battery is receiving a charge, or if it’s currently being discharged. It also details whether a 220V battery charger is connected, or if the unit is on standby.

However, the feature I like most is the app’s ability to tell you how many amps are being drawn from the auxiliary battery. This information quickly tells you how much power your fridge is drawing, as well as any other connected loads, such as a cell-phone charger, LED camping light, or even a 12V air compressor.

Actually, it’s not just the app which shows you this information, if you hold down the ‘V/A’ button on either side of the box’s voltage meters, the digital dials flip between showing how many volts are left in the battery, to how many amps are being drawn.

A screen grab from the NL Connect app, showing the load current of 3.1A currently being drawn by a 12V camping fridge.

An additional 15A input plug point allows you to connect a solar panel – provided you have a solar regulator – that you can then monitor in terms of input charge.

And finally, the unit also boasts a configurable start timer and low-battery warning that can be adjusted to suit a variety of applications.

Other features of the Grey Box include…

  • A split-charging system
  • Four USB charge ports
  • Two 12V DC sockets (Cigar)
  • Two Hella-type sockets
  • Two 50A Grey coupler plugs
  • NL5 Intelligent Charger port (charger available separately)

NOTE: If you can’t decide between a relay-based dual-battery system (Grey Box), or a DC-DC based dual-battery system (Green Box), then the following link may help. The article details the pros and cons of relay- versus DC-DC split-charging systems:

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