Hardware Review: WonderPack for Wonderswans from Flashmasta.com

If you’ve just joined us, we’re covering some accessories for the Wonderswan series of handhelds. So far, we’ve reviewed the Flash Masta flash cart. Today, we’re going to cover the next most logical component to buy for your Wonderswan. And that item is the 2000 mAh WonderPack Li-Po rechargeable battery pack from the same people who supplied the Flash Masta! So yeah, you could only buy the Flash Masta and call it “good”. But do you really think that one AA battery is going to be in it for the long haul with you? Better read what I have to say!



‘With all these recent upgrades and accessories for the WonderSwan (IPS LCD Kit, Headphone Adapter, Flash Cart, etc.) the WonderSwan is outgrowing its single AA battery. Introducing a new USB-C rechargeable battery pack for the WonderSwan.


  • Smart Charger Detection Technology
  • Ultra-Low Quiescent Stand-By Current
  • Charger Over-voltage Protection
  • Short-Circuit Protection With Automatic Restart
  • Under-voltage Protection
  • Temperature Monitoring and Thermal Shutdown
  • Dynamic Power Management’



  • Battery Life.  Let’s start off with what everyone who is looking at this would be wondering. How much play time are you going to get out of this. It’s obviously better than the single AA, so what are we looking at here?
    Well, their website touts fourteen plus hours if you have a backlit IPS display. However, I couldn’t test that because my Wonderswan Color is running on the OEM screen still. So I turned it on with the contrast on high so the screen was as bright as it could be. I turned the sound to the highest setting too. And then I just let it run and melted my brains out from the nonstop music counted the hours. It lasted all day, all night I believe.
    I’m willing to bet if you had the volume turned off, it could probably last a smooth twenty-four hours, it’s crazy to think about. Now I’m definitely certain if the sound was off and you used a first-gen black and white Wonderswan, you could get into a second night. I’m unsure how long this would last in a Wonderswan Crystal with the sound on or off.
  • Size. This may be its only true downside. And it’s less of a downside and more of a silver lining because they’re smart about it. Yeah, it’s bulky, and upon first glance, you might think it’s a bad thing. But they make the most out of it, so let me explain how.
    First off, the bulk sits between your hands when playing the system in landscape mode. If you play a vertical game (tate mode), you’ll also have it out of way. The average person will find that their hands don’t come into contact with it. The next thing that they did was to put a little red foot on the bottom of the bulk. That enables you to stand the Wonderswan uprightwhen not using it.
    I love that for two reasons. Number one, it gives it a built in display stand for the shelf which saves you $15-$20 on a stand. Secondly, you no longer risk scratching the front side or the sticker on the backside. Because of the stand aspect, I’d really like an alarm clock homebrew. Then I can have a backlit screen with this battery pack sitting on my side table and have it be my bedside clock replacement. The only bummer of the stand, I will say, is that you can’t stand it up while charging. I’d love to see a USB port on the back as well. The system could be smart enough to only let you use one USB port or the other.
    So, while there is bulk on the battery, at least they give it attributes. Just remember though, if you have a form-fitting Wonderswan carrying case that this will not play nice with it. I bought an original Game Boy carrying case and it was much better.

  • Compatibility. The compatibility is with all versions of the Wonderswan. This is confirmed on their website. Because, while there are little variations between them, the battery compartment and backside shape remain the same. I did find pictures of people using it on the first-gen Wonderswan and can confirm it sticks out a little bit further. This is because it was designed with the form factor of the later models in mind. However, it all works the same and the picture I saw was hard to even tell it protruded at all. So I wouldn’t worry if you were concerned about the fit of the model.
    Best of all, the WonderPack is compatible with the other device mods supplied from Flashmasta.com..It works with the ones that are fully decked out with the flash cart, the headphone jack adapter, and the screen mod. As we said before, it’s made with the screen mod in mind, so that means you’ll find yourself still getting good life out of it even if your device is drawing more power for the brightness of it all.
  • Build Quality. Just like with the Flash Masta flash cart, the internals (2000 mAh LiPo battery and PCB) are housed in a tough 3D printed plastic. I’m guestimating that this one is also PLA. Until I find out for sure, mark that one under “rumor”.
    The plastic on the inside edge touching the actual Wonderswan is a smooth plastic that was obviously fabricated. This was incredibly smart of them and has intent behind it. It prevents rubbing and scratching of the system. This was chosen over the rough 3D plastic. On the bottom, there is a USB-C port. More on that in the next section as it deserves its own.
    Unfortunately, I don’t have a scale that can weigh ounces/grams. However, given how ergonomic the Wonderpack is, I really feel like it’s non-intrusive. The weight of it doesn’t do anything more than double the weight, as it seems. And the weight of the Wonderswan in the first place is very lightweight. So the weight is also non-intrusive.
  • Charging. Now we can talk about the USB-C port. I think it’s great that they use the modern and likely future-proof USB-C port rather than a microUSB. I also feel the need to mention how strong it USB-C ports are. They always grab tightly and take a little bit of strength to pull them out. Not to mention the lack of worrying about orientation as you do with the microUSB port.
    Now, be aware that the WonderPack also comes equipped with an LED indicator. The LED lets you know as you’re playing the status of the charge (picture down below of the red LED in action). For the curious, a great perk of the WonderPack is the ability to charge while playing. If you’re charging and playing at the same time, I didn’t see any long waits. I just wanted to preface that I used a fast charger to get my short charge times.
    When I charged it, I often put it on the charger when it got low but never died. I would charge it while watching a movie and it would be back to green by the movie’s end. I do know that it has the ability to detect a fast charger versus a standard charger. So if you use a regular charger, it may not be done charging in the time it takes to watch a movie. I used my fast-charging USB dock each time, so your mileage may vary.
  • Fit. I only took the time to put the WonderPack on once. It’s not like it’s a total pain in the butt to put in. But since it’s bulkier and the spot for a AA is smaller, it’s all a matter of having to line it up properly. The WonderPack is so perfectly measured that it fits very exactly in the AA battery slot. It is so form-fitting that it takes some getting used to when first putting it in. You have to come at it straight on and if there is the slightest angle to it, it won’t work. Or at least not without you jamming and twisting and pushing. I recommend that if you’re at an angle, simply back out and try again.
    Now, it’s worth mentioning that the accurate fit doesn’t mean that it’s too big or bulky for the secondary lock features that the Wonderswan has. So rest assured that the lock function and release tab still works with it. And then one last point with regards to the fit. If you have a shell on your Wonderswan, it will have to come off, the WonderPack is snug and form-factor specific. You can likely have a vinyl skin on your Wonderswan, but not a shell of any kind.
    When you’re touching the WonderPack, have caution. The website says that it has a failsafe to make sure the contacts only push voltage through when it makes contact with the WonderSwan’s metal battery terminals. However, you should always exercise caution because technology is fallible and just because it didn’t buzz you last time doesn’t mean that it won’t 10 years from now. Just be safe and power it off when you take it off of the Wonderswan and you’ll be fine.
  • Ugly. Well, in all fairness, it’s not ugly per se. I only deemed it “ugly” because I couldn’t think of a better word in English for it. It’s more just “unfortunate” that the colors chosen for their theme are unmatching. So while the WonderPack is loaded with lots of intelligent choices, it doesn’t look too pretty.
    However, because I love the Flash Masta ecosystem of products, I will adapt to accommodate them. I will swap my shell out to an all black shell just to match. Both this and the Flash Masta WS flash cart I own are primarily black. The same goes with the headphone jack adapter that they sell. Lots of you won’t care about it matching though, you just want to play games. It’s probably just myself who is vein and cares about their belongings matching the accessories.
  • Power Saving. The WonderPack comes with a bevy of power options. We’ve almost discussed everything, but anything I missed we’re going to talk about right now. First I want to start with the only physical power option. The on/off switch.
    The WonderPack can be physically switched off. This is so that the system won’t suck the battery dry while it’s not in use for long periods of time. They also intelligently hid the switch on the underside so that you cannot accidentally press it or see it. Also, it’s small to the point that I had to use a tiny tool to flip the switch. So even if it were on the outside, you wouldn’t accidentally switch it.
    The downside is that the switch doesn’t tell you which way is off and which is on. You can charge it even if it is turned off, which is good. But you’d have to test it by inserting it into your Wonderswan to see if it’s off or not. This is only on if you’ve stored it for a long time and are just coming back to it, of course.
    Now, you don’t need to bother with the on and off switch if you play the Wonderswan often. It’s only really used for storage situations or if you want to charge faster, you can unplug your WonderPack and power it off. However, I don’t know how much faster it will be compared to charging it while connected to a powered down Wonderswan. Last of all, be aware that your WonderPack will arrive to you powered off. It will likely need a charge to get it green state. But once you have it flipped on and fully charged, you’re good to play!
  • Internal Pictures. This is not a pro or a con. I just wanted to allocate a section so that you could see some internal pictures provided to us from the brains behind the product. I didn’t disassemble my own and you won’t have to disassemble yours. They are transparent enough with us to show what’s inside and that it’s all clean. They also wanted, for those wondering, to answer the question of the single wire. Here’s the direct quote, “That’s a safety feature for the battery.  It’s a thermistor that senses the battery’s temperature and can shut off the circuit if the battery is overheating. I don’t think we’ve had any batteries overheat, but from an engineering standpoint, we decided to include that just in case.” So not only has this not happened to them yet, they’ve built in a failsafe to stop it before it could happen. Anywho, here’s the pictures (click on them if you want to enlarge)!

Final Thoughts:

The bottom line is this. It’s big and honking but worth every single penny if you are a total fanboy fanperson of the Wonderswan! This probably isn’t for casual players that don’t really care if they use a AA that they burn once a season. It’s for those of you who burn through weekly AA’s.
If you add on more accessories and whatnots that can drain more of the battery, just know that the WonderPack has your back! Upon first seeing it in person, I told myself that I wasn’t going to use it after reviewing it. It quickly changed me into a believer for real. Now, I’m going to swap my whole shell to a black one just to get it to match because this thing is a masterpiece!

Purchase Link:



Other Flash Masta Products:

Flash Masta Flash Cart for WS

WonderBeat 9480 Headphone Jack Adapter for WS

Backlit IPS Screen Kit for WSC


All Flash Masta Products:

FlashMasta.com Shop

About V1RACY

Check Also

Hardware Review: Hammerin’ Harry Concrete Collection

This review is over yet another release from Retro-Bit and partners. We’re going to talk about …