In a recent column National Luna described the benefits and pitfalls of using a larger 40A DC-DC charger over a smaller 25A unit. 

You can read that blog piece here, otherwise, here’s the summarised version…

Although a 40A DC-DC charger appears to be the ultimate dual-battery solution, the benefit of using a 40A charger is only truly seen during the ‘bulk’ stage of the recharge cycle. 

Once you include the ‘absorption’ stage in the overall process, the total recharge time is similar for both a 25A and 40A DC-DC system.

This is because the total recharge time is determined by the battery’s technology, and not the charger itself. Simply put: The battery is the limiting factor, not the DC-DC!

However, because a 40A DC-DC charger will reduce the bulk charging time of your auxiliary battery, the real benefits are realised when you need to quickly replace used energy within the first 3-hours of driving. 

If you’re using a lithium battery, you could potentially knock that time down to 2-hours.


With the above points in mind, National Luna is due to launch a brand new 40A DC-DC power pack. It will be the first of its kind on the market, and further cements the company’s position as a global leader in dual-battery solutions. 

National Luna previously launched a 25A DC-DC portable power pack in 2019 (aka: The Green Box). Due to the success of that product worldwide, and calls for a 40A version, they’re now launching a far punchier unit, one that incorporates their built-in 40A DC-DC charger. 


So why would you want a 40A DC-DC power pack instead of a 25A unit? Well, the higher amperage is beneficial when…

  • You want a much faster charging time within the first 3-hours of driving – which is arguably where it matters most
  • You have a large capacity battery
  • You want the extra solar capabilities
  • You’re powering a load (a fridge or another appliance) at the same time as charging the battery
  • You have an alternative power source such as a wind generator

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Other features of the 40A National Luna Green Box include: 

Plug ’n play solar input

Lithium-ion compatibility

Built-in battery voltage meter

220V input charging port

Customisable faceplate with multiple power inputs

True 40A output current

5-stage intelligent charge algorithm

AGM, Gel, Wet, Calcium, Lithium-Ion support

Alternator input up to 32V

40A, 600W MPPT solar regulator

Supports solar panels up to 42V

Separate auxiliary DC input up to 32V

Smart-alternator compatible

Battery temperature compensation for safe charging

Short-circuit protected

Reverse-polarity protected

Over-voltage protected

Over-temperature protected

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