Instructables

How to make a solar iPod/iPhone charger -aka MightyMintyBoost

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Step 3: Add the battery and charger

Picture of Add the battery and charger
MMinty13.jpg
Now cut a notch out of the other side of the Altoids tin to fit the charger and secure the charging circuit to the bottom of the Altoids tin with double sided adhesive. Reconnect the battery and the MintyBoost PCB to the charging circuit. Make sure nothing on the bottom of either one of the circuit boards is touching the bottom of the Altoids tin.
 
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jonsleepy1 year ago
Awesome idea! And I noticed Adafruit's new optimized solar charger, too! However, I still feel attached to AA batteries - I have several devices that use them. I would rather avoid using the lithium polymer battery packs - to me, they feel like added weight and a "middleman", even though I realize they can store more charge per gram of weight. Is there a way to get power from the panel into a circuit and into the AA batteries in the original Mintyboost? Therefore I could swap AA batteries into and out of the Mintyboost, and recharge as needed, without the use of the Lithium battery?
Honus (author)  jonsleepy1 year ago
Yep, you could do that. Basically you would just substitute the LiPo cell and charging circuit. Just use two AA rechargeable batteries with a compatible charging circuit instead- you need to make sure you get the right type of charging circuit for whatever battery chemistry you AA batteries are.
Thanks for the reply! So then there's 2 circuits.. one to convert the 1.2 (or 1.5) volts x 2 AA batteries into 5V for USB out.. and the second to convert whatever the solar panel can put out into whatever the batteries need to charge. Is that it? Say I want to charge 2-4 AA NiMH batteries. I'm not sure I know how to determine what I'd need, but I'll look around.

Actually, I found this:
http://www.instructables.com/id/Heavy-Duty-Solar-USB-Charger-In-a-tin/

but I'd want to have the option of using whatever solar panel I want, and adding more batteries. Just not quite sure how to make that modification or if this is the best way to go. Aah well, I'll get there!

Thanks.
Honus (author)  jonsleepy1 year ago
That's it- the MintyBoost circuit takes your battery voltage and converts it to a stable 5V output. The charging circuit takes the output from the solar panel and uses that to charge your battery that powers the MintyBoost.
rnicholls13 years ago
Nice project. I am thinking of taking this one on however i want to make my own case, if you could tell me the approximate specs of the "altoids" tin, that would be great.
Honus (author)  rnicholls13 years ago
Here's the standard size Altoids tin inside dimensions (not taking into account the rounded corners)- 93mm long x 58mm wide x 21mm deep
lorddavis64 years ago
i think it,s great project!! i give 5/5 for it!  :)

I am happily working on this project now.  I wanted to make it as compact as possible with minimal holes in the tin to prevent dust from getting in (hello desert).  I managed to squeeze the boards in there so the USB (A)  is fully on the inside with a tight slot that the male USB  just fits.  The barrel just fits into a drilled hole on the other side.  Do I need to worry about shorting from contact with the connectors to the Altoids case?

ps. I used sticky-back velcro on all the parts so I can readily interchange them later if I want to use them with other projects.  Thanks for the very clear instructable.
Honus (author)  LightsAction4 years ago
As long as there's enough room for it to move around without coming into contact with the tin you should be just fine.
moclov5554 years ago
 Hi thanks for the instructable, i got all the parts this morning and worked on it all day and i'm having some trouble. Let me first say that i am building the mintyboost from scratch (first on breadboard) with all the parts from the mintyboost website. When i plug an ipod into the mintyboost circuit alone (powered by AAs), the ipod charges normally, but when i try to use it with the LiPo and sparkfun charger the ipod doesn't register that anything is connected and will not charge. I measured 4.25 volts between pins 1 and 4 of the usb and about 3.11 volts on each data pin. Also when i use the LiPo with the mintyboost the power inductor gets really hot and when i use the AAs it barely gets warm. I measured the output of the LiPo usb charger and got 4 volts without anything plugged into it (except the LiPo battery) and 3.967 volts with the minty boost circuit and ipod plugged in (even though the ipod does not say its charging.) Even stranger is that the voltage continued to drop; 3.966,3.965,3.964, about every second (indicating to me that either the ipod battery is charging or the inductor is draining it through all of the heat it's generating). The mintyboost is designed to have a 3 volt input and the LiPo is giving it more than it needs. I'm confident that my mintyboost circuit is correct because it works perfectly when i use it with AAs, the problems only occur when i bring in the LiPo side.
Sorry for this rambling comment but i could really use some help.
Thanks!
Honus (author)  moclov5554 years ago
At this point I have no idea what is happening. I know of multiple instances where people have used a LiPo to power a MIntyBoost and haven't had any problems whatsover so it seems as if something is funky with your MIntyBoost circuit or possibly component selection- the inductor never got hot on mine. I'd give the Adafruit forums a try.
csmo5 years ago
Hi I have put mine together and am having some trouble. Initially all seemed to be working fine. Two things have begun to happen. 1) When I connect the Minty Boost PCB to the charger and the charger is either charging via a wallwart or the sun the red indicator light goes off. That is, when the solar cell is plugged into the charger and the charger to the battery the red light comes on, but when I plug the MintyBoost into it the light goes out instantly. Actually, that's not entirely accurate: when the PC is plugged into the charger the faintest red light is detectable and then when it's unplugged it instantly goes bright red. 2) If I leave the PCB disconnected and charge either via the sun or the wallwart for just a little bit I can then plug in the PCB, plug in my Ipod Touch and get the whole thing to work--briefly. Then it stops. Bad battery? Thoughts? Many, many thanks Christian
dmhjah5 years ago
I haven't had any luck with double sided tape. Can you glue gun the pcb boards to the Altoids box? Or maybe use liquid electrical tape?
Honus (author)  dmhjah5 years ago
A glue gun should work.
jtroj205 years ago
where can i find the solar panel?
This is very cool i built it and now love it very good job
fthrjack5 years ago
Are you not risking short circuits using an Altoids tin? - I would have thought a plastic project box from Maplin or Radio shack or something would have been a safer bet, easier to cut, looks neater, no short circuits etc. Great project though, I might just build one of these :)