Double Capacity MintyBoost with 4-AA Battery Holder Modification

Step 15 Final inspection

As you can see in the first two images below the battery holder fits tightly under the inside rim of the Altoids tin. This helps hold the battery holder in place. You can also see in the second image an example of using JB Weld to hold the modified terminal (from step 8) in place.

The last image below shows the completed project. Since we are using a battery case very similar to those encountered in many consumer electronics the double capacity MintyBoost has a familiar feel to non-technical users. This was an important design consideration since most of the people I have made these for are not technical. After installing batteries and closing the tin case the device has a very sturdy feel. You might even say that it's "Curiously Strong".

I'm not sure what it is about Altoids tins. But when people see something useful made out of one they seem to get a real kick out of it. And I get a kick out of making them. I made a bunch of these for Christmas gifts and have given some to fellow volunteers who rely on portable power sources.

Thanks for taking the time to read my instructable. Your comments are welcome and an honest rating would be appreciated.

Special thanks to Lady Ada ( www.ladyada.net ) and adafruit Industries ( www.adafruit.com ).

Thank you for all the great comments and feedback!

If you're interested in buying one of these completed kits they are now available here...
bit.ly/dh15cJ

Comments

[joshnosh]

where is the Joule thief? and do you really need diodes on the batterys. they cant be helping

[RoysterBot]

The Minty Boost circuit works like a Joule Thief in that it trades current for voltage and is able to leach out power from the batteries. I added the diodes in this project for safety. Since I was building these for non-technical people I wanted to make sure the design could handle someone installing batteries that were in radically different states of charge or mixed battery types. If you could guarantee balanced batteries of the same type were always used then you could remove the diodes and get more efficiency. In my case the safety factor was worth the few tenths of a volt drop that results is isolating the two sets of batteries with the diodes.

[joshnosh]

ok so its not a jewel thief at all really its a dc-dc converter
a jewel thief would be able to keep running till acid started leaking from the battery's where as this will die when they battery's are about 1v so i little less then most electronics but still not a joule thief. i don't see a real jewel theft being any good though as the battery has already given up most off its power at this point and probably wouldn't charge a phone/ipod
"few tenths of a volt drop" you make it sound like a low number. forward dropping voltage off the ones you linked is 0.45v which is still a considerable amount.
personally iv never had a problem with mixing battery's and i wouldn't put them in
but you have a valid point so that's up to you
tell me why did you not wire the battery's in series?
you could also avoid the diode problem by just having 2 battery's running and 2 in storage.

[RoysterBot]

Each set of 2 batteries is wired in series. Then the sets are connected in parallel. I did this for convenience when charging devices with larger batteries. I also build these with one set of batteries which leaves space for a spare set of batteries or a charging cable.

[joshnosh]

interesting
i ment why not all the battery's together in series giving 6 or so volts
i cant find what chip its based on but iirc it can take 6v and would allow you to squeeze more out off your batts and would be more efficient

[RoysterBot]

The chip's manufacturer recommends limiting the max input voltage to 5. There is a danger of exceeding that with fresh alkaline cells. You could probably get away with that if you use rechargeable cells. Once again I was designing for safety.