I tried quite a number of those chargers. Some are poor quality, some generate VHF noise etc.A good solution is the Cabstone 2100mA charger:
The same thing is also sold under the name “Wicked Chili 2100mA”
http://www.amazon.de/Wicked-Chili-Fast-Port-optimiert-spezifisch/dp/B008CPO6X2
On the FR Amazon I only find a Cabstone 4000 mA and a 3100 mA. Do you happen to know whether they are equally good in terms of noise as the 2100 mA?
The problem is that the noise is radiated only on very specific frequencies.
You could tune sequential values in 25kHz steps and find that out of say 100 channels maybe only 10 get it. It is never a case of completely wiping out the whole VHF band. Well… the Turkish-made Sattrans car holder for my Thuraya 7100 did do exactly that 
So testing for interference is difficult, and would be much harder on the NAV bands unless you have an IFR 4000 or similar and set the power level just above the flag level.
The problem will obviously be massively airframe (wiring) dependent. Same with the KFC225 autopilot servo burnouts.
Finally, remember that to charge an Ipad at 2A you need a different charger than to charge an Android tablet at 2A. They use incompatible methods to indicate the presence of a charger (as opposed to a PC) to the device being charged. Some threads on it here.
Do you need a different charger or a different cable?
I’ve a 15000mah USB battery that seems to have no difficulty charging any device that I’ve thrown at it, including an Android phone and an iPad.
The two classes of devices need a different arrangement on the two data wires.
Apple use two voltage levels (normally done with 4 resistors, though I can’t see why 3 can’t be used), while the others just short the two wires together.
I could be wrong but I don’t think you can achieve 2A charging with just one charger – unless it is switchable, or somehow auto-detects the device (which would be nontrivial).
On the FR Amazon I only find a Cabstone 4000 mA and a 3100 mA. Do you happen to know whether they are equally good in terms of noise as the 2100 mA?
I did not try myself but another pilot reported noise issues with the 3100 mA version. If you can not find the 2100 mA anywhere in France send me a message. We have those chargers in stock and I could sell you one of them.
The problem is that the noise is radiated only on very specific frequencies.
That is very true but we delivered probably over 100 units of the 2100 mA Cabstone for charging iPads together with our ADL120 devices. And we did not get any complaints yet, so this specific charger it is rather well tested by now…
No personal experience of these, but they look the part http://www.charge4.co.uk/
Mark..
If you can not find the 2100 mA anywhere in France…
Actually I found the Wicked Chili on Amazon.fr. Thanks
No personal experience of these, but they look the part http://www.charge4.co.uk/
That’s a really interesting product, from a company which looks like they thought about it!
Totally non-certified but…
I wonder how they auto-detect Apple v. non Apple? I would think it does need some USB comms. Or maybe they present one setup and measure the current for a few secs, then present the other setup and measure the current again, and settle on the setup where the current drawn was higher 
Typically output is 5.25v to cater for loss in the USB cable, regardless of load.
I am not sure what they mean by “regardless of load” (to do feedforward cable loss compensation you need to be in control of i.e. supply the whole USB cable) but they got the 5.25V right!
I am the designer and maker of the Charge2 and Charge4 USB chargers, so am able to answer the questions Peter has raised. I did e-mail him directly and he suggested I register and post here for everyones benefit.
As Peter said, there was indeed some thought into the design of the chargers, and various iterations of design too. What started as solving a problem for a friend has turned into the chargers you see on the website.
Typically output is 5.25v to cater for loss in the USB cable, regardless of load.
I am not sure what they mean by “regardless of load” (to do feedforward cable loss compensation you need to be in control of i.e. supply the whole USB cable) but they got the 5.25V right!
What this meant to say is that the voltage output of the chargers is ~5.25v regardless of the load on them, it doesn’t drop as the load increases. The helps prevent too much drop in USB cables, especially under high load. I have amended the website to, hopefully, make this clearer.
I wonder how they auto-detect Apple v. non Apple? I would think it does need some USB comms. Or maybe they present one setup and measure the current for a few secs, then present the other setup and measure the current again, and settle on the setup where the current drawn was higher
As for device detection, that is slightly more complex, as it is the device which detects the charger and decides how much power it can draw. The chargers use specific hardware to manage each port independently, under software control. As such, they will dynamically adapt to what ever the attached device is, making them pretty much universal and extensible too. They can run in a mode as you describe, as a last resort.
If people have any questions relating them, please feel free to ask, I will try to answer as best I can.
Feedback on them is also welcome too.
Jeremy Curtis.
