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Energen DroneMax P40


Energen DroneMax P40

The Energen DroneMax P40 is a big, heavy portable charger that can provide power to four DJI Phantom batteries simultaneously.


  • Pros

    Portable design. Includes charging cables for Phantom 3 and 4 batteries. Dual USB charging ports.

  • Cons

    Pricey. Heavy. Doesn't include its own charger. Take eight hours to fully recharge.

  • Bottom Line

    The Energen DroneMax P40 is a big, heavy portable charger that can provide power to four DJI Phantom batteries simultaneously.

By Jim Fisher

DJI Phantom owners are used to only getting 20 to 25 minutes of flight on a fully charged battery. Drone pilots who need more time in the air stock up on batteries, but also need to buy an accessory charger to replenish more than one at a time. You can buy a three-battery charger for the Phantom 4 or a four-battery charger for the Phantom 3 from DJI for about $90, but those won't do much good if you're in the field without power. Enter the Energen DroneMax P40 ($399), which recharges up to four batteries at a time and includes a big internal battery that replenishes those four batteries in the field. Its priced much higher than the DJI options, but you're paying for convenience.

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The DroneMax is a big, heavy, silver brick with a rubberized black bumper. It measures 2.7 by 5.9 by 6.9 inches (HWD) and weighs 7.2 pounds. A zippered, padded carrying case is included. The case can be carried using an integrated hand strap, or with the included shoulder strap. Its main compartment holds the battery, and there's an interior zippered pocket that houses the included cables and documentation.

The P40 has four circular DC charging ports on its front, along with two female USB connectors, and another circular charging port that's used to recharge the high-capacity internal battery. Eight charging cables are included—four for DJI Phantom 3 drones and four for DJI Phantom 4 drones. You don't get a charger to replenish the battery itself. Instead, you need to use the charger that shipped with your drone to do so.

There's a power button in the middle of the face. Press it once and then again, holding it for three seconds, to start charging a connected battery. I took an empty Phantom 3 Advanced battery and connected it. The charger topped it off in about an hour—the same time that the standard DJI charger takes. After charging one battery, the P40's blue LED battery indicator showed that it had about 75 percent capacity remaining, exactly as expected.

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That's in line with what Energen promises. You're supposed to be able to get four full charges out of its internal 27,236mAh battery, regardless of whether you're charging one battery four times or four batteries at once. You can expect to get a slower charge when utilizing all four ports, but Energen estimates that recharging four batteries will only take about an extra 10 minutes versus one. Of course, if you used the USB ports to charge other devices, you won't be able to get four full drone battery charges from the big power brick.

The battery itself takes about eight hours to fully recharge, although it can get to 90 percent capacity in less time. If you're using it at home, you can plug it into the wall to recharge while charging your drone batteries at the same time.


The Energen DroneMax P40 is, at its heart, just a really big battery. It delivers on its promises—it recharges DJI Phantom batteries, and does so when you're away from a power outlet. Are four extra flights worth a roughly $300 premium over DJI multi-chargers that must be plugged in to a wall to work? That's up to you. Just remember that, while being billed as portable, it's not lightweight. Putting it in the back of your SUV before going out for a weekend of camping and drone flying is not a problem, but I wouldn't want to hike a trail with it weighing down my backpack.

headshot By Jim Fisher Senior Analyst, Digital Cameras

Senior digital camera analyst for the PCMag consumer electronics reviews team, Jim Fisher is a graduate of the Rensselaer Polytechnic Institute, where he concentrated on documentary video production. Jim's interest in photography really took off when he borrowed his father's Hasselblad 500C and light meter in 2007. He honed his writing skills at retailer B&H Photo, where he wrote thousands upon thousands of product descriptions, blog posts, and reviews. Since then he's shot with hundreds of camera models, ranging from pocket point-and-shoots to medium format… More »

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