Minty Boost Extra





Introduction: Minty Boost Extra

About: Favorites enjoy robotics, python, Raspberry Pi, Arduino, and making in general.

A v. 2.0 Minty Boost I just bought from AdaFruit (very similar to the one in Lady Ada's Instructable except that it apparently works better with iPhones now). I used a larger Altoids-type tin, not the gum tin - that gives me room for a spare set of batteries. I also made the hole in the side without just clipping a notch. Nothing special really, but I hadn't really seen that so I figured I post it.

Step 1: Making It

The Minty Boost is made per the kit instructions (available at Lady Ada's site). I wanted the USB port to be fairly flush, and I didn't want a big notch in the side. I had thought about using a Dremel to cut the hole, but after googling around a bit saw a mention of just using a hole punch. I put the minty-boost inside where I wanted it, then marked the outside with a pencil at the approximate location. It worked great - made 3 overlapping punches. Then I used a small file to enlarge the hole to the right size.

Step 2: Why Bother?

I keep the Minty Boost in my bag as an emergency charger, Although the circuit is supposed to draw very little power at rest, eventually it will drain the batteries. This way I always have at least one fresh set. I've got some low drain NiMH on order so I don't have to keep buying AA's. I've tried it on an iPhone, iPod Touch, and old iPod mini - worked fine for all of them.



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    50 Discussions

    Nice USB charger... If you wanted to make a version of your own, then use a Voltage Divider! I used Matt Jenkins instructable, and Matt is a well respected member here, and the VD worked great. Just click on my name, and my charger will be there. Here's a link to it! Happy building and check out my flashlight for another 'ible. Happy Building!

    2 replies

    How much battery is drained if there isn't a switch? I thought if there is nothing drawing current from it, then it wont suck up power.

    2 replies

    There's no switch. It pulls very little power with nothing drawing current. According to another comment, the drain is not much worse than just the spontaneous drain of the batteries themselves. /K

    Ok thanks, I've had the mintyboost 3.0 for a while and i was just wondering if putting a switch on it would make any notable difference

    I'm a complete newbie but could you not make another cut on he tin and then add a switch between the MintyBoost and the batteries so that they aren't drained. Thoughts?

    5 replies

    You could, easily enough. I had thought about that as well. But Lady Ada's design seems to be pretty good - I've had batteries in for months and not seen much drain. I'm sure they'll wear down eventually, but at this point for me there isn't a lot of impetus to put in a switch. /K

    No switch was needed in the Minty v1 or v2, but in the Minty v3 circuit it seems a switch would help.

    MAX756 quiescent current: 60uA
    Linear 1302 quiescent current: 200uA

    I use rechargables, but they are all Sanyo Eneloops (low self-discharge) and they remain nearly fully charged for months on the shelf. In a MintyBoost, they only last a few weeks even though the Minty has not been used any.

    A Linear rep I spoke with claimed the Mintyv3 had "a direct path through the diode to the output when the part is in shutdown which will drain the battery" (I'm guessing this means the circuit lacks something necessary to automatically switch it into logic controlled shutdown mode, which the Linear spec sheet lists as 15uA... quite a lot less than 200uA!).

    If any folks could confirm this or comment or suggest improvements (to take advantage of shutdown mode) that would be awesome. AdaFruit is really busy on new products and my sense (opinion really) is that new revisions to the Minty for problems like discharge are just not a priority.are not a high priority.

    around 2 years to drain the batteries if left plugged in.

    Too late for me on this one, but I'll do it differently next time. And great info for the next person to take it on. Thanks yazug!

    I just bought minty boost and when I finished assembling it I put the batteries into the battery pack and the boost converter chip heats up and gets really hot. Also when I went to see what the voltage was for the USB output it wasn’t get the 5v like it is suppose to. If you know what the problem is will you please let me know. Thank you

    3 replies

    My chip has gotten hot when I changed phones to one that draws a lot of current. Apparently sometimes soldering together the 2 and 3 USB leads can help ensure the phone sees it as a USB charger (see the very last set of instructions on It worked for me.

    Not sure about the voltage. You could try Lady Ada's forums (

    I tried soldering the 2 USB output together on one of my minty boost and the boost converter chip still heats up Are to older versions of Minty boost more reliable? If so do you know where I could buy an older version? Thanks

    I'm sure you could. There are other Instructables showing how to use a solar cell to charge Minty Boost batteries. I think there is also a thread over on Lady Ada's forums.

    from LadyAda's comments and analysis the drain is the same order of magnitude as that at which batteries discharge by them selves.

    1 reply