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

Step 3 Add the battery and charger

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.

Comments

[rnicholls1]

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]

Here's the standard size Altoids tin inside dimensions (not taking into account the rounded corners)- 93mm long x 58mm wide x 21mm deep

[rnicholls1]

In doing some more research i have also discovered that sparkfun have discontinued the single cell LiPoly charger. they seem to have an alternative, could you tell me if it is still suitable for the job? i have provided the link below

http://www.sparkfun.com/products/10161

[Honus]

That should work just fine- it's pretty much the same except they've switched the IC manufacturer.

[lorddavis6]

i think it,s great project!! i give 5/5 for it!  :)

[LightsAction]

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]

As long as there's enough room for it to move around without coming into contact with the tin you should be just fine.

[moclov555]

 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]

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.

[csmo]

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

[csmo]

UPDATE: I tested my battery and got 3.17v. It will charge my Ipod touch for about a minute and then stop. The Ipod is close to full charge already. Perhaps I should run it down and see what happens? Thanks

[csmo]

BUMP. Any ideas? Thanks

[crunch777]

When charged, the battery should be well over 3.9v, the charger will stop at 4.2v according to the data sheet. Read the data sheet and directions on the sparkfun website as it will explain what happens with different sources. 3.17v on the battery means it's close to 0% as the battery will stop itself from going below 3v. The charger will always favor the barrel plug over USB and for maximum charge throughput you want to use a wall wart as it will deliver the max 280mA. Try to top off the battery and try your testing again.

[crunch777]

Also worth noting that if the battery is anywhere between 2.8v and 3.1v, the charger will only deliver an average of 40mA for Prequalification Charging Current. This means that if the battery is really low, they will only send a small amount of current until a certain point and then it will deliver the full current depending on the input method used. So try and get that bettery charged, it may take a while. Also for troubleshooting, try taking your minty boost and put the 2XAA battery on and see how charging behaves. Troubleshoot the individual components of the project to narrow this down.

[Honus]

Christian, I don't have any idea- it sounds really strange. It may be possible that you have a short somewhere. Have you tested the MintyBoost circuit separately to make sure that it's working properly? Can you post a pic of how it's all connected? Has the LiPo battery ever been fully charged? It sounds like you're not charging the LiPo battery when the MIntyBoost circuit is plugged in- that's why I think you might have a short or something wrong with the MIntyBoost circuit.

[csmo]

Crunch777 and Honus Many thanks for the replies. I indeed might not have been giving it enough time; I will let it charge much longer. Though today I tried it after charging via the sun and the wallwart for approx 14 hours and it only charged my IPod for about 20mins before crapping out again. I'll charge it for longer. What's weird is that when it stops charging I can unplug the PCB, plug the li-po and charger into the solar cell or the wallwart and red light will come on again. A short sounds like a good possibility, but (and excuse my ignorance) wouldn't a short keep it from working at all? Or could it work for a bit and then short out? So, it seems quite possible that I was not letting it charge enough, but it does seem odd that when it stops charging I cannot get to begin charging again until I unplug the MintyBoost. There are two pictures below--one of the whole thing and another of the soldering on the circuit board. Thanks Christian

[Honus]

I would definitely try testing the MIntyBoost circuit by itself and then go from there.

[csmo]

PS: I did not mention that after a few minutes the battery will not charge if the PCB is plugged in. That is, if the charger is either hooked up to the solar panel or the wallwart the red light will go out after a short time if the PCB is plugged in. Odd. A short perhaps. Thanks!

[crunch777]

Honus is right, troubleshoot the individual parts. If you find the minty boost the problem, post close up pics. We would need to see the other side of the minty boost, you may have a component backwards. Check the mintyboost build directions again to make sure. The JST plugs are tight going in, perhaps you broke a lead on the charger? Close up pic would help. Test the volt on that JST port, should equal the BAT voltage.

[csmo]

Thanks again to both of you. I desoldered the JST and rehooked up the MintyBoost battery pack. It worked so.... I've now resoldered the JST and am waiting for things to charge up. I will do this: "The JST plugs are tight going in, perhaps you broke a lead on the charger? Close up pic would help. Test the volt on that JST port, should equal the BAT voltage." Thanks again. Will post when I've fooled around some more. Best wishes Christian

[blindside360]

This is very cool i built it and now love it very good job

[Honus]

Thanks! Any troubles building it? Be sure to post pics... I'm starting to think about making some really cool cases for these to fit into (not that there's anything wrong with Altoids tins.)

[dmhjah]

I have the original cases my itouch and ipod came in. I wonder if maybe they are to big to be practical -- not that Altoids tins won't work:)

[jesus jones]

Nifty little accessory Honus. Makes me wish i had an ipod just so i could build one of these. ... for the case, maybe put the solar panel inside the lid, so it can be closed, and protected when not charging.

[Honus]

The latest clear case version that was sent to the Dept of Energy had the solar cell under the lid so it was better protected.

[jesus jones]

ah k cool. i wouldn't be suprised if the whole concept was worked into the next iphone, or some competing brand. i only just discovered this site, and i'm glad i did. good to meet you.

[dmhjah]

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]

A glue gun should work.

[jtroj20]

where can i find the solar panel?

[Honus]

All the supplies are listed on the tools and materials page. Other options are listed in the FAQ section.

[fthrjack]

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 :)

[Honus]

That's exactly right- the double stick foam tape acts as an insulator. Having said that I just designed a clear acrylic case for it that's much more professional looking- hopefully I'll be able to produce them pretty quickly. The downside, of course, is that it will no longer be MInty.... :D

[joejoerowley]

Well if you use the double stick foam tape there shouldn't be a problem. You could always coat the inside of the tin with some kind of paint or liquid electrical tape I imagine.