Q. What is the diagnostic port for?

A. The port offers enhanced information over the status of the ports.  In addition to the status lights the diagnostic port will also show the status of a port, if a device is attached or removed, and also the power being drawn per port, in realtime.  It emulates a serial port over USB, so it universally supported, the port settings are 57600, 8 bit, No parity, 1 Stop bit (8N1).

Pressing any key brings up a menu, offering some more details and allows for inputting and assigning custom profiles to the ports.  This enables the supplies to be easily extensible for devices that do not conform to the various standards.

Q. I’ve seen other USB chargers aimed at GA/LAA that are cheaper.

A. No doubt, we’ve seen quite a few too.  It’s possible some may work OK with the device you have today, but are they built to the same performance and safety levels?  The technical testing requirements these products should go through given the intended environment make interesting reading, in particular to operating outside the ‘normal’ ranges.  Such as input voltage 50% above normal for 5 minutes, short circuits on all output ports for a minimum of 1 minute, voltage spikes of up to +/-60 volts etc. should not be a problem.

Even if not aiming for the likes of TSO approval, basic protection should be designed into any product given the cost of the devices people want to power, and the electrical environment encountered within light aircraft.  Charge2 and Charge4 have features to help protect devices as much as possible.

In addition, the Charge2 and Charge4 are self contained units so can easily be used elsewhere, such as in vehicles (cars and trucks), boats, even when camping with a suitable battery.  They do not have any exposed electronics unlike some other products out there, and are supplied with a choice of power lead within the price.  Combined with universal device support they are offer a simple, single box, solution to charging devices in the air.

Q. Whats wrong with a generic plug in charger?

A. Interesting question, perhaps the question should actually be ‘is there a generic plug in charger suitable for use in the air?’  Anyway, back to the original question, and the answer really depends on which of the huge number of units you are talking about.  Broadly we have seen several common issues with them; high level of RF interference, poor voltage regulation especially under load, narrow device support, lack of safety/protection features, and the potential to damage the device under charge because of one (or more) of the above.   

Remember generic plug in chargers are sold as just that, to be used for short periods to charge a device, with lower output being needed as the battery charges.  So to use one for extend periods can cause issues of their own.

The generic cigarette charger should have been tested for radiated emissions, not all of them have been through anything other than very rudimentary testing, some cheap Chinese ones haven’t even had that.  None of them are required to have conducted emissions tested, being battery powered.

One of the most common problems is the stated power output.  Say a generic charger is rated at 3 Amps, when you actually try to draw close to 3 Amps from it the voltage drops and fluctuates, often causing it to overheat.  Often this is combined with being built to identify itself as a particular type of high power charger, so your device may try to draw as much power as it can.  This can lead to damage to to your device, the charger itself, and be a hazard when in the air.

We looked at a number of them when researching the original problem which led to the development of our chargers. The real issue is simply they were never designed for use in the air.

Q. What are my fitting options for aircraft?

A. If your aircraft falls into the Light Aircraft (LAA) or US Experimental Amateur Built (EAB) class aircraft then you can permanently wire the units into the aircraft, naturally with suitable protection for the power feeds the same as any other device, and with sign off according to your local rules.  If you have an open cockpit, you can use USB extension cables and tuck the unit in a dry area and fit waterproof USB sockets.  Just be aware over the cable limitations given in the USB Charging FAQ.

For EASA certified aircraft permanent installation is permitted under Issue 2 of the CS-STAN regulations.  Details of what is required to achieve this are given here.

Q. Can I run a unit from a battery pack?

A. Yes, no problem, providing the input voltage is between 11v and 30v and of sufficient capacity the supplies will work quite happily.

Q. What does a microcontroller give me?

A. The obvious thing you can see is the status lights, which let you know what is happening on each port.  Behind the scenes it manages the USB ports for supplied current, faults, etc.  The basic principle within the units is that the USB ports are powered off (i.e., they will supply no power) until a device is actually detected as being connected.  Only then does the unit actively look to find the most suitable power profile for the device.  Once a device is in a steady charging state the status light goes green to show all is OK.  The port is then continuously monitored for faults or the device being disconnected.

As there are an ever expanding number of power hungry devices, it also enables the supply to be extensible.  Should a device come along that it cannot correctly handle, additional profiles can be added into the supplies via the diagnostic port.

Q. Can I use USB extender cables, to mount USB sockets around an area?

A. Yes, you can, but you need to be careful.

The extension cable should be no longer than 1m and you cannot use any type of USB extension cable.  The only recommend ones must have at least 20AWG (or 0.5mm cross section) cables on the +5v and GND wires.  Commonly these will be identified as 20/24 or 20/28 cables (20AWG for the power and 24/28AWG for the data).  This is needed to ensure, at higher charging currents, the voltage doesn’t drop too much in the cable.  We don’t specify this for our own amusement, it’s basic physics to ensure your device gets the voltage it needs and the cables do not overheat.

You could then, for example, get hold of a USB A to B cable and fit one of these panel mount USB outlets from Neutrik. You can get covers for them too, if required.

Q. What is the power input connector type?

A. All units are fitted with a Molex Mini-Fit connector, specifically one Molex 43645-0200 connector and two 43030-0002 crimp pins is needed for the power lead.  This is a latching connector, so will not vibrate loose in a panel.  The positive terminal is the one on the left, when looking directly at the back of the unit.

When crimping the connections ideally you should use, as we do, a Molex crimp tool (part number 63819-0000).

Q. What is LSZH or ETFE cable?

A. These are two types of cable covering. Low Smoke Zero Halogen (LSZH) is used for the cigarette lighter cable, so in the unlikely event of a fire in the area of the cable the quantity of smoke and toxic fumes generated are kept to a minimum.  

ETFE is short for Ethylene tetrafluoroethylene, a type of cable covering which offers a high degree of corrosion resistance and strength, whilst being light.  It is often used in aircraft wiring harnesses for these reasons.  It also has low fume toxicity when exposed to flame.

Both are chosen for their safety, whilst by no means the cheapest cable types out there, they are the best choice for the intended environment.  Safety is key after all.