Scenario:
I recently acquired a small, indoor R/C Helicopter that requires 6 AA batteries to operate the controller. There's also a small 3.7v receptacle that extends from the controller to charge the helicopter.

Problem:
As you can imagine, flying a few minutes or even a few hours with this can be taxing on the batteries as it is being used to power and charge two objects.

Idea:
I figured it'd be a neat idea to create some rig that allows me to convert a wall plug directly into the controller so that I can pretty much have as much juice without the cost of batteries.

What I need help with:
I have little experience on doing much of this, though I have done a bit of research. I could use someone's expertise.

1 AA battery = 1.5V DC at anywhere ranging 400-2400mA
Logic dictates 6 batteries ~ 9V DC ranging 400-2400mA

1. I recently hunted around for a DC wall adapter that is 9V DC 1800mA, I'm assuming this is OK to use right?

Also, I read on this other question asked that piquéd my interest in something - https://www.askmehelpdesk.com/electrical-engineering/battery-power-751109.html

2. It is true that a controller might not even need a 9V adapter. Would a 5V wall adapter be OK or would you imagine it be a little too underpowering? The next easily available wall plug would be 12V - that sounds like it might be a bad idea.

3. If my logic is sound and I may be on the right track, I could possibly use some guidance on putting these things together. I happen to have also acquired some essentials - electronic coils/soldering kit/10 megohm multimeter

*Update*

So as it turns out, talking to a friend - modern tech probably doesn't require a full juicy 9V at all... I probably would've ended up frying my stuff :P ha!

He suggested I break open the controller and I'll probably find two banks of 3x AA for a total of 4.5V - I imagine a 5V wall outlet would be suitable.

With hundreds of wall chargers now at my disposal, I figure a 5V DC 2A interchangeable USB wall adapter is ideal for this. Though with the research I've done so far, it looks like many USB ports are limited to 100mA - 500mA

Do you think this is OK or should I go for a USB to 5.5mm barrel convert?

Use the multimeter to confirm that the batteries are indeed wired in two parallel sets to give 4.5v total. If so, then I think a USB wall charger would work just fine - they can out out 900 mA at 5v steady state and up to 3A when charging. The trick will be how to solder the leads of the USB cord to the controller battery terminals. FYI, pins 1 and 4 of a standard Type A USB connector are +5v and ground, respectively.

Thanks for confirming my questions and for the USB pinout!

As far as the soldering leads - I'm probably going to use one or two wooden dowels to imitate the battery body while using wire ring connectors to play the positive/negative connectors.