MintyBoost 3.0


I built a pocket size USB charger using a MintyBoost 3.0 USB charger, a 3.7 v, 2600 mAh LiIon battery and a built-in LiIon battery charger in an Altoids Wintergreen Mints tin. It can be used to recharge a cell phone, iPod or other small USB rechargeable device.

I’ve had‘s MintyBoost 3.0 kit and USB LiIon/LiPoly charger (this is v1.1) for a while but I never put them together. I liked the size of the Altoids gum tin of the previous MintyBoost versions I have built but I wanted a little more charging capacity than 2 AA batteries could provide. I wanted a suitable battery and enclosure that didn’t compromise charging capacity and size.

Using ladyada’s calculations for battery power, I decided to use a 3.7v 2600 mAh LiIon battery.

The battery’s capacity:
MintyBoost mWh = 3.7V * 2600 mAh = 9620 mWh input

The amount of current it can provide:
Output mAh @ 5V = 9620 mWh / 5 * 80% = 1539 mAh output (80% is the conversion efficiency)

Number of iPhone 4S recharges = 1539 mAh / 1430 mAh (iPhone battery capacity) ~ 1.1

The MintyBoost kit requires the soldering of a few components to a circuit board. I also made two mods to the internal battery charger. With this version (1.1) of the adafruit LiIon battery charger, removing the resistor R4 and replacing it with a 1K ohm resistor allows the internal battery to be charged at 1000 mA.

The internal battery charger has connections for external status LEDs. I connected current limiting resistors between the board and LEDs, then mounted the LEDs in holes in the Altoids tin. The green LED indicates that the internal battery is charging and the yellow LED indicates a fully charged battery. (LiIon/LiPoly charging tutorial at Adafruit Learning System)

The battery and circuit boards are mounted in the Altoids tin with double sided foam tape. I made a miscalculation in the height of the LiIon charger taped to battery – the cover won’t close when the charging cable for the internal battery is attached.

To charge the internal battery, a USB Mini B plug supplies the power to the internal battery charger as in the photo above. To charge a device, a USB Standard A connector is used. There’s also enough room in the Altoids tin for storing an Apple 30-pin to USB Cable.

MintyBoost 3.0 in Altoids Wintergreen Mints tin

Below are charging test results with an iPhone 4S starting with battery at 49%:

Time (minutes)      Charge (%)
0:00                           49%
0:15                           58%
0:30                           66%
0:45                           75%
1:00                           83%
1:15                           89%
1:30                           93%
1:45                           96%
2:00                           97%

If you are interested in the MintyBoost design process:

iPod 5G to Classic

iPod 5G with iPod Classic front face plateAs with all Apple products, after a few years they get long in the tooth. My 5G iPod was introduced on October 12, 2005, and after a couple of years, it’s still working OK, even the original battery. It is a little beat up, so I decided to do a couple of things to “refresh” it.

You can change the interface of your 5G ipod to make it similar to the one on the iPod Classic. You can see it over at

I also decided to replace the scratched front face plate. While looking on eBay, I saw that the iPod Classic aluminum front face plate had tabs that looked very similar to my 5G’s, so I bought one.

When I received it, I noticed that the tabs on the Classic face plate were not separated by a gap. I used a Dremel cutting disk to remove the material on the Classic face plate so the tabs resembled the ones on the 5G.

iPod Classic Face Plate

iPod 5G Face Plate

It looked like it was a drop-in fit after that, but when I did a test fit, the screw holes on the cover’s tabs didn’t reach down far enough to line up with the holes on the iPod’s frame. I used a round jeweler’s file to make the holes in the tabs a little oblong and then I was able to screw the cover to the frame.

iPod 5G frame

With the Classic face plate mounted on my 5G iPod, there is a little less than a 1/64″ (~.396mm) gap between the front face plate and the back plate. I may have been able to shorten the height of the Classic’s tabs to get it flush, but I didn’t bother. Also the click wheel is slightly above the front surface of the face plate, but not annoyingly so.

iPod Classic front face plate (L) and iPod 5G front face plate (R)

Finally, because the Classic front face plate is aluminum, it is now much more difficult to remove – it doesn’t flex as easily as the plastic one.

It seems like a worthwhile mod if you’re going to replace the front face plate anyway because the mat finish doesn’t show fingerprints like the plastic face plate and it’s less susceptible to scratches, unlike the plastic one.

MintyBoost 2.0

Mintyboost 2.0

ladyada has updated her MintyBoost battery pack and charger with a higher output step up converter.

She writes, “The upgrade was necessary as the latest Apple products really need a lot of current to charge and hopefully they will work better now!” The MintyBoost uses 2 AA batteries and an Altoids tin for a case.

I’ve built two V1.0 kits and used them to charge a cell phone and my iPod. The MintyBoost is great because it’s small and will give you the additional power to keep your phone or iPod running when you need it.

You can buy the kit and get technical information at

iPod Classic Comes to the iPod Video

I first saw this story on

iPod Classic

The guys (H3X, bounci.rabbit.123, vettefan, saXas, matthew98, supernatural, and xxDriveNxx) over at have re-written the 5G (fifth generation iPod) iPod’s firmware, so it looks like the new iPod Classic’s.

The new iPod Nano and iPod Classic have a new interface. While navigating through the menus, half of the screen is taken up by a floating image of album artwork.

One thing that’s missing on the 5G version of iPodWizard’s hack that the iPod Classic has is Coverflow. Also the images don’t float, like they do on the new iPods, but iPodWizard’s work is very cool, nonetheless.

When I first used the iPod Classic to iPod Video firmware hack, I had the problem of my iPod going into a “Boot Loop” – after the firmware was written, during the reboot, the Apple logo would disappear while the drive clicked and then cycled again.

My iPod (5G)

Putting the iPod into the disk mode by holding select and play allowed me to do a restore to the original (Apple) firmware. Then I downloaded a version of the firmware “without the boot loops.”