The latest avionics are more efficient than ever thanks to lower current draw, but you’ll still want an external power source for even short periods when running on the ship’s battery. Maybe you’re doing database and software uploads, entering flight plans or simply learning how to use new systems. That’s why investing in a reliable GPU (ground power unit) makes a lot of sense.
One company—Kentucky-based Audio Authority—has dominated the portable GPU market for a while with its smartly designed White Lightning line of GPUs. When we first evaluated the company’s 2860A GPU back in 2011, we liked its compact design, smart user feature set and efficient output.
At AirVenture this past summer, the company was showing off its latest SmartGPU at the Piper exhibit where the latest White Lightning GPUs were providing ground power to the new M700 Fury turboprop single and the rest of Piper’s display aircraft. Audio Authority founder Jonathan Sisk gave us a thorough demo and we immediately liked what we saw.
Powered preflights
If you’ve drained an aircraft battery by leaving the master switch on longer than you should have (in cold climates you can kill a battery during even the shortest of preflights), you probably recognize the value of an external power source. It’s even more critical in turboprops and jets where you want to preserve as much battery power as possible for engine starts.
The latest S28114 SmartGPU goes beyond the call with a host of smart features that make it easy to use, while caring for the battery at the same time. More on that in a minute, but first some history.
Sisk, a longtime aircraft owner (and builder of a Van’s RV kit) who was working on STC projects in the early 2000s got into the ground power business almost by accident. His company was making power supplies for the consumer electronics market when maintenance techs asked if he could build something to power the aircraft they work on. These early models worked so well, Sisk was encouraged to bring them to market.
While that was nearly 20 years ago, like most electronics these GPUs have become smaller, lighter, less expensive and more feature rich. These days, GPUs benefit from the stability and efficiency of switching mode power modules, with tightly regulated voltage output. That makes them safe for connecting to aircraft equipped with modern electronics—something you should be mindful of when connecting any external power supply.
Connected GPU
The latest White Lightning S28114 SmartGPUs (which weigh 16 pounds and measure 18 inches long by 5 inches wide and 7 inches high) are equipped with both wireless Bluetooth and Wi-Fi transceivers. That means the operator is no longer tethered to the GPU, where in the past they needed to have a line of sight to the unit to know how much current is being drawn, to name one parameter. The latest SmartGPU interface has a smartphone app that mirrors the data shown on the GPU’s high-resolution 4-inch display. This includes current draw, voltage, the AC power input voltage that’s going to the GPU, ambient temperature, operating status, the elapsed time the GPU has been connected, plus soft keys for pausing the GPU without having to physically access the unit. You can also set up multiple aircraft and operator profiles, plus event logging and a smart programmable timer for automatic GPU shutdown to prevent the GPU from working when you aren’t around to monitor it. The unit also has built-in safety protections from overload, over-voltage, over-temperature or short circuit. The simple app is compatible with both iOS and Android platforms.
Battery maintenance
Partnering with VDC Electronics, the SmartGPU also has an option for the onboard BatteryMINDer aviation battery maintenance tender. Unlike a charger that can ruin a battery, this is a battery tender that’s smart enough to keep the battery topped off. The longer you have a charger connected to the battery, the more critical overcharging becomes. It has to be temperature compensated because the proper float voltage is critical in keeping the battery fully charged but not overcharged. Sisk noted that because the VDC BatteryMINDer is connected to the SmartGPU’s internal power supply, it can provide more power output for constant charging that’s appropriate for batteries in larger aircraft.
In our demo, the unit had a 10-amp charger suited for larger batteries, but there are 4-amp versions for smaller batteries. With all of these options there’s a dedicated connector on the front of the SmartGPU for connecting the BatteryMINDer cable to the input connector that gets wired to the aircraft battery.
Worth mentioning is that the SmartGPUs are for 28-volt electrical systems only and we hope for a 14-volt version. We do like that the GPU has a trimmable voltage feature, which allows you to fine- tune the exact output voltage. Some aircraft have multiple batteries and since one battery might be set up for a higher potential than the other, fine-tuning the output allows you to provide the exact voltage needed for a given electrical bus.
Choose your power
Who needs one of these GPUs? We think there are plenty of buyers, actually, starting on the turbine level. “Pilots that operate turboprops and jets know not to deprive even the smallest amount of battery power that’s needed for engine starts in fear of hot starts,” Sisk told us and he’s right. But there are also piston aircraft operators that will see tremendous utility in one. When starting with a healthy, fully charged battery you can probably get by without external power for maybe 15 minutes. For maintenance ops where you’re doing landing gear swings and other checks, external power is a must. Doing avionics training where hands-on experience is your plan? Plug it in.
Sisk, being experienced in the experimental aircraft world as a builder and operator, found that many kits don’t even have external power receptacles, so he came up with a wiring kit that can be installed so you can plug in a GPU. “I’ve seen so many people trying to do database updates to older navigators, which is a time-consuming process, and get halfway through the update only to have the battery drop below the output voltage threshold that’s required to keep the units going,” he told us.
At press time, the White Lightning line of SmartGPUs (which will be available in September 2024) consists of two models. There is the $2500 S28114 3200-watt unit (115 amps at 28 volts) that’s appropriate for turboprops and jets and the $1600 S28054 1500-watt unit (54 amps at 28 volts) that’s suited for pistons.
The company’s lower end of mini GPUs (available in 14 and 28 volts) start at around $600. You can see the full lineup of products at www.whitelightningGPU.com.
