But before we get to that, let’s explore what an end-of-days power-pack solution should look like…

• First and foremost, it should be portable. Something you can use in your house in the event of a black out, but if needs be, you can quickly throw it in your vehicle and hit the road.
• It would have to accommodate a wide range of battery types, including Calcium, AGM, GEL and Lithium-Ion.
• You need to be able to recharge the power pack in your house, as well as in your vehicle.
• For those occasions when you’re not driving, you definitely want to be able to recharge the battery with a solar panel, without fussing over wires and connections.
• Such a power pack must come equipped with a multitude of output power points.

On that note, I give you the National Luna 25A DC-DC Auxiliary Battery Box (Aka: the Green Box), the only backup power solution you’ll need for the zombie apocalypse. Here’s what it does…

PORTABILITY

National Luna has several power-pack options in their product line, one being a Grey Box, the other a Black Box, and now, the most recently launched Green Box. Their Grey Box solution has been around for many years and is sold in dozens of countries worldwide. That said, the idea behind all of National Luna’s power-pack solutions lies in three concepts: portability, durability, and usability.

BATTERY TYPE

As you probably know, how a battery is recharged is vital to its performance and safety. For example, you can’t recharge a Lithium-Ion battery the same way that you would recharge a lead-acid battery. With this in mind, you want a power pack that can accommodate and recharge a host of battery options.

The National Luna Green Box can be connected straight to your vehicle’s main starter battery / alternator, and, depending on what setting you opt for, it will adapt its charging profile to best suit the battery you’ve selected – whether that be a Calcium, AGM, GEL, EV Traction and/or Lithium-Ion.

DC to DC CONVERTER / DUAL-BATTERY SYSTEM

As mentioned before, a critical aspect of any power-pack solution lies in its ability to recharge from your vehicle’s alternator while you’re driving. This is otherwise known as a dual-battery system, where you essentially equip your vehicle, caravan or camper with a second battery that automatically recharges at the same time as your vehicle’s main starter battery.

Once you turn the vehicle off, an isolator switch (within the dual-battery system) automatically disconnects the two batteries so that you can power a 12V fridge or camping light on the auxiliary battery without running the risk of draining your vehicle’s main starter battery.

Most dual-battery systems are simple in design and function, but as newer vehicles on the market make use of variable voltage alternators, the demand for a more sophisticated dual-battery system has arisen. That said, a number of manufacturers now offer DC to DC dual-battery systems that are able to boost the alternator’s low voltage output in order to fully recharge the auxiliary battery.

Most DC to DC dual-battery systems are permanently wired into your vehicle (such as the one featured above), but National Luna took the concept one step further and built their DC to DC system into a portable option. As far as I know, no other company has done the same.

SOLAR INPUT

If you’re going to camp off grid for more than 3 days (without driving your vehicle) you’re bound to need a solar panel in order to keep your power pack topped up.

These days, solar panels are up 66% cheaper than they were just 4 years ago, and they’re more efficient, too. The cost to buy a high-quality solar panel is surprisingly affordable. However, when you factor in the cost of a high-quality MPPT solar charger on top of the panel price, the costs do add up.

A solar charger is a device which converts solar energy into usable battery energy. How efficiently (and effectively) it does this is determined by the quality of the solar charger, and whether it’s a PWM charger (the cheap type), or a MPPT charger (the expensive type).

Fortunately, the National Luna Green Box is equipped with a super high-quality MPPT solar charger that has a maximum current and power rating of 25A and 375W respectively. The Green Box is also fitted with a heavy-duty Brad Harrison plug that connects directly to the MPPT charger. This means, connecting your solar panel to the power pack is literally as easy as plugging it in. The built-in MPPT will do the rest in terms of converting free solar energy into usable battery energy. Toss in a high-quality inverter, and you have yourself a complete 220V battery pack that can run your TV, wifi and a few LED lights at home, too.

POWER POINTS

The Green Box has no shortage of output power points, including one Hella 12V socket, two auxiliary 12V sockets, four 3A USB ports, and two heavy-duty 50A in/out connectors. With such a diverse range of plug points, you can power or recharge everything from a cellphone or tablet, to a GPS unit and/or even a large-sized camping fridge.

But the best feature of all is that you can also swop any of the above-listed power points for an alternative connection. In other words, if you want two Hella plug points instead of one, you can swop the 12V Auxiliary port for another Hella socket, or, any other National Luna widget.   

You’ll be pleased to hear that each available plug point has its own safety fuse. So if one fuse blows, it won’t affect the operation of the other plug points.

ACCESSORIES

As I’ve just mentioned, there are a number of widgets (sold separately) that can be used within the Green Box, as well as several optional extras – the most useful of which being the Remote Monitor.

Although the Remote Monitor isn’t pivotal to the Green Box’s function, it is an invaluable piece of kit in terms of information – particularly where solar power is concerned. Aside from displaying the battery’s current state of charge, capacity and battery type, the Remote Monitor also tells you how much energy your solar panel is producing, how much energy your vehicle’s alternator is producing, as well as the battery’s operating temperature. This last point may not sound that important, but battery temperature is critical to the battery’s lifespan, as well as how quickly it will accept a charge.

The Green Box has a dedicated port on its front panel where the monitor plugs in, and you can mount the monitor’s high-contrast display on the power pack itself, or in the case of a vehicle setup, on your dashboard where you can keep a close eye on it.

The National Luna 5A Intelligent Battery Charger is another vital accessory for your Green Box. Again, the power pack is equipped with a quick-connect port that’s designed specifically for National Luna’s 5A charger, but you can also connect any other brand of charger to one of the power pack’s input ports.

In the case of the National Luna Intelligent Battery Charger, the 5A unit has a boost function, as well as a maintenance function. Meaning, it can restore a deeply discharged battery if needs be, but you can also leave the charger permanently connected to the Green Box without having to worry about overcharging the battery or boiling its electrolyte.

It that sense, with an Intelligent Battery Charger connected, your Green Box can also function as a form of UPS (Uninterrupted Power Supply). However, this last application will depend on what it is you’re trying to power and how many amps it’s drawing.

TO SUM UP

So, in short, the National Luna Green Box is a portable power-pack solution that…

• You can use in your vehicle, as well as in your house
• Can be recharged via solar power, 220V power, or 12V vehicle power (alternator)
• Can accommodate a wide range of battery types, including Calcium, AGM, GEL and Lithium-Ion
• Can power your 12V camping fridge
• Boasts a number of input/output power points
• Is made from an impact resistant and highly durable material 
• Is 100% safety compliant with fused power ports, an overload trip switch, and reverse polarity protection  
• Features a customisable faceplate
• Offers a range of optional accessories, including a digital monitor and purposefully-made battery charger

FAQ

1) How easy is it to install the Green Box into my vehicle?

Super easy, all you need to do is run the supplied 16-gauge cable from your main battery’s terminals, to the Green Box’s location, and include a 40A fuse that’s supplied with the kit.

2) Can I have the Green Box connected to my vehicle’s alternator and the solar panel at the same time?

Yes you can. The Green Box will give preference to the alternator’s power input, but as soon as you turn the vehicle off, it will immediately start using solar energy.

3) What’s the biggest battery I can fit into my Green Box?

This will largely depend on what battery technology you opt for, but in some cases, you may be able to get a 140A/h AGM battery to fit. Typically though, most 110Ah batteries are an easy fit.

4) If I want to use the Green Box in my home for load shedding / power outages, what size inverter should I use?

The inverter size will depend on what it is you’re trying to power, but if it’s just for your TV, wifi and one or two LED lights, a 500VA Pure Sine Wave inverter will do the job. However, keep in mind that any appliance that generates heat will require much more battery- and inverter power, so avoid trying to power your kettle, toaster or hair dryer.

5) What size solar panel can I connect to my Green Box?

The unit’s built-in MPPT is rated at a maximum input voltage of 42V, and a maximum battery charge output of 25A and 375W. However, for most camping applications, a 135W panel is often the most convenient in terms of panel size, packing and portability. 

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The 4×4 travel market has no shortage of hot debates and shootout tests. Whether it be vehicles in a comparison, or tyres, suspension, fridges, winches, or even camping pots for that matter, people want to know what works “best”.

However, there’s one subject that many overland travellers are generally keen to steer clear of, and that’s the topic of batteries and split-charging systems.

So why is the topic so controversial?

Well, it has a lot to do with varying vehicle types, alternators, preferred battery locations, power needs, and of course, different driving times / distances. There are so many variables to consider that it’s almost impossible to say: “This dual-battery system is better than that one”.

With this in mind, we laboratory tested various dual-battery kits, along with various battery types, to determine which setup performed “best”. However, rather than deliver a conclusive result, the tests highlighted just how complex the subject really is.

The following graphs highlight what we found in terms of when a solenoid system works best, and when a DC-DC system should be the preferred choice.

SOLENOID TEST

The above mentioned tests concluded that in certain instances, if your vehicle’s alternator output delivers a constant voltage of 13.9V or more, then a 20A to 25A DC-DC system will actually slow down the recharge process. In fact, above 13.9V, the solenoid system radically out performs (within the first few hours of driving) any 20A to 25A DC-DC charger on the market, regardless of what type of battery you use.  

As shown in the graph above, the solenoid system (blue line) rapidly outperforms a 25A DC-DC setup (red line) within the first 3-hours of driving. You’ll also notice that at this voltage (13.9V), the solenoid system doesn’t quite make it to full capacity (98% charged).

However, in saying that, it will also take the DC-DC system more than 5-hours (driving time) to fully recharge the battery.

This explains why so many dual-battery systems work well within the first year or so, but as time goes by, the system becomes less efficient. The reason for this is because the performance of the battery is declining with each partially recharged state. This is especially important for wet-cell batteries.

That said, it’s strongly recommended that an Intelligent Maintenance Charger be used (after your trip) no matter what type of system you use. The mistake many of us make is to believe that a few hours drive home will do a sufficient job at recharging the auxiliary battery, when in fact, the battery still needs a maintenance charge in order to reach a full (storage friendly) state.

DC-DC TEST

The graph below highlights the obvious advantage of a DC-DC setup once the alternator’s output is as low as 13.5V.

Although the solenoid switch is still outperforming the DC-DC system within the first 2-hours of driving, the bigger issue is that the solenoid noticeably fails to fully recharge the battery (even after 8-hours), and the best it can do is an 86% recharge state.

If you continue driving for more that 2-hours the DC-DC system starts to drastically outperform the solenoid switch.

To further complicate things, the tests showed that your chosen battery type (wet-cell, deep-cycle, AGM and lithium) played a fundamental role on how well the DC-DC system worked.

Put another way: If your DC-DC charger is unable to change its charging profile to suit certain auxiliary battery types, it could potentially ruin your battery.

What’s more, because DC-DC systems are heat sensitive, once engine-bay temperatures reach 50ºC+ (a very normal under-bonnet temperature), many DC-DC units shut down. Which is why it’s often best to install your auxiliary battery and DC-DC system in the boot of your vehicle – away from heat. Incidentally, solenoid switches don’t have the same problem.

SUMMARY

• If your vehicle’s alternator delivers a constant voltage output of 13.9V or more, a solenoid switch is the preferred choice.
• If your vehicle’s alternator delivers a constant voltage output that’s less than 13.9V, a DC-DC charger will do a better job at restoring the auxiliary battery’s (near) full capacity.
• No matter what dual-battery system you install, it’s advisable that an Intelligent Maintenance Charger be used to service the auxiliary battery and restore it to full capacity after each road trip.
•  Aside from the 13.9V threshold, the tests do highlight a growing need for DC-DC chargers within the modern-vehicle market and their increasing use of variable voltage alternators.
• Most high-end DC-DC systems include other functionalities such as solar compatibility and lithium-ion support. So if either of those features is important to you, then a good quality DC-DC system is the obvious solution.

Brought to you by National Luna

The post Which dual-battery system is best: Solenoid or DC-DC? appeared first on 4WD Revolution.

Whether you’re a weekend camper or long-haul overlander, there’s no denying the convenience of a solar setup. Aside from having free energy to power your camping fridge, a solar panel can also be used to maintain your auxiliary battery for optimum service life.

With this in mind, here’s a basic guide on how to connect a solar panel to your dual-battery system or Portable Power Pack.

WHAT DO YOU NEED?

Simply put: A solar panel, a regulator, some heavy-gauge cabling, and of course, an auxiliary battery.

Although solar panels may vary in cost and quality, what’s just as important, is the regulator that goes with it. In short, the regulator is what converts the panel’s high voltage into a voltage that’s suitable for your battery; which means, the regulator must support your panel’s current and voltage rating.

Typically speaking, regulators are either MPPT or PWM in design. MPPT units are generally more costly, but noticeably more efficient in terms of how much energy they extract. PWM regulators may not be as efficient, but they are basic in function, reliable, and low cost.

It should also be noted that some panels have built in regulators, so be sure to check this before you purchase your panel.

INSTALLED DUAL BATTERY

If your vehicle is equipped with an on-board / installed dual-battery system, you simply connect the panel to the regulator, and the regulator to the terminals of your auxiliary battery.

On that note, it’s best to have your regulator as close to the battery as possible in order to limit voltage loss between the two. For this reason, it may be best to avoid panels with built-in regulators if you want the panel to be mobile and positioned away from your vehicle – resulting in a long cable and noticeable voltage loss.

What’s more, make sure you connect the regulator directly to the auxiliary battery, and not to your vehicle’s main / cranking battery.

PORTABLE POWER PACK

As far as Portable Power Packs and Auxiliary Boxes are concerned, the installation is even easier: simply connect the solar panel to the regulator, and the regulator to the 50A grey coupler on your power pack.

On that note: National Luna recently launched a DC-DC Portable Power Pack, also known as the Green Box. This product is hugely versatile in that it features a 25A DC-DC dual-battery system, a built-in MPPT solar regulator, and a multitude of output power points.

The Green Box makes the installation of a solar panel super straight forward because the MPPT is already built into the unit. All you have to do is plug your solar panel directly into the Green Box’s solar input port, and the built-in DC-DC system takes care of the rest.

The National Luna Green Box is a portable power solution, that doubles as a dual-battery system, as well as a mobile solar setup. Best of all, you can use it in your vehicle, your campsite, or even in your house during load shedding.

WHAT CABLE SHOULD YOU USE?

Cabling is often the most overlooked subject when it comes to dual-battery systems and solar solutions. Ideally, we recommend nothing less than 16mm² cabling between batteries, and 6mm² from your solar panel to regulator.

How bad can voltage loss be? Depending on its diameter, a light-duty cable may double your auxiliary battery’s charging time, and in some cases, prevent the battery from fully recharging and fail as a result.

Brought to you by National Luna

The post How to connect a solar panel to your vehicle’s dual-battery system appeared first on 4WD Revolution.