Short answer, no they won't charge AA batteries as expected.

Long and boring answer, it makes no sense to implement a Ni-MH charging and detection IC since the gamepad already ships a Lithium battery, wich is charged in a diferent way, via diferent pins.
What's interesting is that the gamepad while wired is pulling ~90uA from the AA batteries, while a very small amount of current it still there and might deplete the batteries over long time.
Also, the gamepad has a hard time turning on with battery voltage below ~2.5v (1.25v each), it means NiMH rechargeable batteries might use very few % of total capacity, even Alkaline batteries might discharge only to around 50% capacity. After successful bluetooth connection it uses around 40mA of current, without vibration. Decent AA batteries should last 10-20 hours, probably more if no vibration.

Sorry, I don't know if they haven't anything planned to change the X-Box version. You can lurk the 8bitdo sub-reddit (info sometimes gets leaked there) or try contacting them.

Yeah ok, I was also kind of skeptical it would do that. Oh well, I guess I'd use the separate AA charger then and keep changing the batteries, in case I end up using them.

I still need to inspect if the original battery ís ok, I just noticed that often the gamepad would refuse to "power on" (no LEDs or anything) unless I plugged in the USB-C cord, yet it wouldn't charge long after that either, the red recharging LED would go off in five minutes or so, as if it was full already.

So I presumed something was wrong with the battery, but I can't be fully sure since I did seem to have other problems with it as well, ie. quite often it would just keep seeking and not connect to Switch, etc. I installed the latest firmware to it though, just in case it fixes anything.

If I can confirm its battery is dead, I guess I could buy a replacement as they are so easy to replace, I'm sure I could find some. And in the meantime, either use (rechargeable) AA batteries, or use it wired.

That Ultimate gamepad with magnetic ("hall effect") analog sticks sounds interesting though, maybe I should buy one too...

I got my 8bitdo Pro 2 wired yesterday and so far I'm quite happy with it. I'll have to see how good it holds up long term but so far it works really well.

There's one thing though I haven't figured out yet: How do you switch modes between XInput and DirectInput? The manual and even the FAQ on the 8bitdo webpage don't say a single word about that.

I don't have the pro2 but the Ultimate wired switch modes by pressing X or B while connecting the USB cable (your buttons may vary due the diferent layout).
I recall having a hard time figuring out as well. Mostly because the status led was blinking and I found no information whatsoever about it. As usual, Reddit was the place to actually find anything useful.


Edit: after re-reading, the intructions above are not very clear and someone from the future might use this thread as reference, so:
to change modes on the Ultimate Wired versions (I assume the same on the Pro2), disconnect the controller from the PC, press X (for Xinput, GIP to be more precise) and connect the controller to the PC while pressing X. For DirectInput (Android, Raspberry, older Linux versions) press B instead.

Sorry, I didn't notice your question earlier. The site took me to the other reply.

1. Yes. I tested the Switch version. I don't know about the X-box one, but I'm assuming it's the same.

2. No. It comes with a rechargeable battery that is built in.

3. The store page shows raspberry pi compatibility for the X-box version, but not the Switch version. I don't have a raspberry pi, so I can't test if the Switch version is compatible.

Since we are talking about gamepads, I will ask my strange question too. Which of the modern gamepads is better for a person who actively used a gamepad many years ago, back in the days of PS1 (even before the release of the first dualshock) and therefore used to control with the arrows, and not with an analog stick? Yep, I know that I'm a dinosaur :D

I had a look at the FAQ and the C version, wich don't support Ultimate Software does actually have a combination to increase or remove the deadzones. Just test it and it does work however with no deadzones the controller is kinda "not precise", with some "jitter" when it resets the position to zero.

I don't know if it's my particular unit but compared to my old pro+, testing with AntiMicro wich maps the analog to a -32000 to +32000, any time I release the analog it resets to a dead zero.
The Ultimate C however, sits between -1600 and +600. Don't know if is just cheap pots (it's a 20€ controller after all), very loose production tolerances or just need some contact spray/lubricant to help precision (wich I do once a year on the pro+).

With that said, the gamepad ships with some deadzones and it's not a issue playing most of the games, at least I've never noticed a issue even playing Asseto Corsa.
Just want to leave the details here cause the manual is scarce and information hard to find. Actually, it seems 8bitdo don't delve much in details like in the past on the manuals, the print below shows what operating systems the controller support and it's clear what the intent is.
For what's worth, Im also a dinonsaur since I find weird the way the kids always uses the analogs. I only use them when absolutely need, otherwise always use th D-Pad.
Was so cool seing the kids trying to play Street Fighter on a analog a few months ago MMUHAHAHAHAHH

Can't really recomend a gamepad but stay the heck away from Xbox 360 controllers, the D-pad is obnoxious. Try to look a fighting oriented gamepads as they tend to be very precise.

Yeah, I always looked at them with a fair amount of skepticism) Not only does the change in the location of the d-pad and one of the sticks raise questions about convenience, but also the fact that the d-pad is solid there, and not in the form of four separate buttons, involuntarily brings up unpleasant flashbacks from the days of the NES and some of its clones, in which the one-piece d-pad was such a torment...

Therefore, it is not clear what to buy. Gamepads from Xbox and the like do not look very convenient, and there are a lot of bad reviews about PS4 / PS5 gamepads in terms of quality.
I really miss the days when gamepads were convenient and almost indestructible (the only problem that arose then was the torn rubber bands under the buttons, and was solved in just a couple of minutes)

You are cruel! I like it :D

As far as I know, most controllers D-pad are a single piece, including the Playstation 3 and 4, they may look like separate buttons but are really a single part underneat the cover. To be honest I find the Playstation way of "separate" the D-pad buttons a bit hard on my thumb after prolonged usage. Having real separate buttons (like the Nintendo Switch) may look interesting but may be akward to use for fighting games, pulling moves like "half-circle" (it's a problem for many people using the keyboard as well, for the very same reason).
Regarding the X-Box vs Playstation layout, I grow up with the Playstation layout but adapted pretty fast after got my first Xbox 360. I use both layouts and don't really think one is better than other, just grab the gamepad and start playing.

The best D-pad I ever used is from the Razer Raion, the buttons are a clicky, tactile feel but have a soft, rubber like touch. I'm pretty sure there are as good or better D-pads but this is the one I have and I'm used to it. It's not a controller for everyone, no analogs, the layout is weird compared to standard, the ABXY buttons are pretty soft and is expensive as heck, I got in a very deep discount though.

On the subject of favorite D-pads, I want to throw in mine, the Dreamcast controller one. I always felt that the slightly more raised pad and pronounced edges compared to a PlayStation-style D-pad allowed for better control. I remember it could be a bit rough on the thumb sometimes after prolonged use, but that happens with almost all controllers. The DC pad felt perfect playing Soul Calibur, I miss couch kumite with friends.

What, when you needed a floppy disk just to get them to even appear and needed a spare 9 or more pin port?

Hey, exact same here. Well, maybe not exact. My first (wired) X-box 360 for Windows lasted almost a decade I think, and it was still working... but I lost it in a flood. When I went to purchase it's replacement about 6 or 7 years ago, I thought I'd save money by purchasing a 3rd party one. I guess it was just me, but I ended up buying two cheap ones and couldn't work with them no matter how I tried. They were too... I dunno, sensitive??? or something. Went ahead and purchased a Microsoft brand again, and was back in heaven. I know there are sensitivity adjustments but I tried everything, both in game adjustments as well as through Windows and I just couldn't get comfortable with either 3rd party X-Box controller and felt back in the saddle again with the Microsoft version..

And the Logitech one??? Wow, I don't know how many years I've had it and it just works. And the best thing about the Logitech one is that I can use it to play all those games without built in controller support with their included Profiler software. In summer/fall of 2023 I just had an amazing ton of fun replaying both Gothic 1 and 2 using the same Logitech controller I used to play them the first time I played them... in the early 2000's (at least I think it was the same one all these years, mayhap I had to buy a new one once and am forgetting). lol. If left with only keyboard and mouse as an option, I would've never played some of the all time greats like Gothic 1 and 2, Two Worlds, Morrowind, Oblivion... on and on.

So yeah, I can't recommend these two choices enough. One (X-Box) is great for all games with built in support and the Logitech for all others.

I like the logitech f310 but the dpad is kinda hard to press maybe because i used dpad mostly for crosscode moving around and my finger would hurt. But all other buttons work fine. And i use it quite frequntly and it's wired
Some other gamepad i used had drift left analog stick sbox something so i don't recommend to buy those. Only used logitech ones properly haven't tried any other gamepads
F310 has no vibration