MintyBoost v4 for iPad?

[kahkheng]

Any plans for adafruit to update the MintyBoost kit so that it can support charging the iPad? I know that AA's will probably be out of the picture, but the kit can make use of some of the lithium cells that adafruit is already carrying. Was browsing around LT's website and came across this chip http://www.linear.com/product/LTC3113. Could this be a possible replacement for the existing LT1302?

[mayotte1]

I would really like to do this for my ipad also!!

[adafruit]

you cannot use a mintyboost to charge an ipad

[CVBruce]

Yeah, I pretty much just figured that out. The hard way. Even with some AA cells Mintyboost would be useful for charging the iPad. I'm going on a 17 hour flight, and have been told there will be no power outlets. My thought was to take several sets of AA's to top off, the iPad along the way. Oh, well.

[coffeeguy]

It's a matter of the iPad charging at a much higher rate than the MintyBoost is designed to provide...it seems to want about 10 watts, or 2A at 5V (5V x 2A = 10W), and might have to do with the voltages at the two data pins as well. I'd try measuring the voltage at the two data pins from your iPad's wall charger as a starting point. Plus, using "AA" batteries won't work well, since they can only provide so much power and only so fast. Maybe something using "C" or "D" cells or a high-capacity LiPo battery pack? iPads have a different wall charger that outputs more current than the iPod chargers which the MintyBoost replaces.

Even though this is somewhat off-topic, you "MIGHT" be able to make a battery-powered charger for your iPad using something other than the LT1302; something which is designed to output around 2A...it would involve a much different design from the MintyBoost though. Basically, you can look at the process documentation to see how ladyada came up with the design and use that as a guideline. Then, you can look at ladyada's discussion on "Apple's charging secrets" here:

http://www.ladyada.net/make/mintyboost/icharge.html

and use that information to figure out how to set up your USB output for a higher charge rate by varying the resistors connected to the two data pins. You'll basically want a design that will give you 5V output at about 2A, then the appropriate values for the two data pins. You can measure the voltage output from your iPad wall charger at the data pins to figure this out.

Lastly, here's a page with some neat information...not very practical since you'd need to spend $100-plus just to fully charge your iPad once, but you can get a better idea of what's involved:

http://voltaicsystems.com/blog/charging ... n-a-phone/

Some folks say that you can turn the iPad off or put it in "sleep" mode and it'll charge at the lower charging rates, but you're still stuck with trying to charge a much larger battery than what you'd find in an iPod or iPhone.

Hope that helps...Your final design might or might not be practical; let us know if you decide to tackle this and how it turns out!

[scottinnh]

My laptop USB is NOT high powered USB. It is a 500ma port. Yet I can charge my iPad 1 with it, so long as all 3 are true:
1) Ignore the "not charging" notice on the iPad
2) Turn off the iPad screen (sleep)
3) Be very patient.. 12 hours later, the iPad was only about 85% charged

It is known that the MintyV3 will not charge the iPad. The question people have is, what needs to change to support slow iPad charging ("slow" mode, because fast mode would be out of the realm of AAs).

The recent Voltiac article goes into a little more about iPad charger requirements, and USB data voltage rates:
http://voltaicsystems.com/blog/choosing ... and-ipads/
They can charge the iPad at 600ma which is within spec for LT1302.

So if I understand this correctly, couldn't one change the Minty data line resistors to gain iPad support?
Or is there something else in the picture which would prevent a solution from being that simple?

[softpen]

I am interested in this topic because I would like one that charges Samsung Galaxy Tab which, like iPad, also requires charging current 5V-2A via USB connector.

Here is my suggestion.
Assuming about 10wh (5V - 2A - charges at about 1 hour),
4 nimh 2500 mah gives about 12 wh - 1 hour charge, or 8 of the same for 2 hours and so on.

Scanning through forum I found,
http://forums.adafruit.com/viewtopic.php?f=15&t=18360&p=105544

So it seems requiring input voltage of 5v or 4.8v (4 serial nimh), efficiency can be increased.

[scottinnh]

For an iPad, just buy the Voltaic V39 USB charger, which can supply 2A @ 5v:
http://www.voltaicsystems.com/v39.shtml
Less capable and slower charging, you can use the V11: http://www.voltaicsystems.com/usb-battery.shtml

[scottinnh]

Adafruit does not support the MintyBoost for iPad.

If you're willing to risk it here are some hints:

"For the lower power output V11 [600mA], only the 2.75/2.00 V (D-/D+) output would charge both the iPhone and the iPad consistently across all models. "
http://voltaicsystems.com/blog/choosing ... and-ipads/

Yes you could alter the USB data resistors on the Minty to produce 2.75v.
Yes the LT-1302 in the MintyBoost is capable of a maximum of 600ma (same as the Voltiac V11 battery charger)

Just because it possible to modify the Minty D+/D- resistors, and the LT-1302 being capable of matching the Voltaic V11.. doesn't mean once you do it that it all works properly.

And even if it does work a little, I would be concerned about the safety of everything.
Who knows how hot the 1302 will get? What might happen to the batteries? If something shorts, could the iPad get damaged?

I do admit to having a curiosity to see an experienced EE at least attempt it. If for no reason other than to demonstrate it is not practical + put the issue to rest.
I wouldn't risk my iPad on it.. I'd just purchase something I know is rated for the task.

[kahkheng]

Thanks for the link to iPad chargers. I think that's just the tip of the iceberg for what's out there in terms of portable of chargers that supports the charging on the iPad. I guess my reason to stick with the MintyBoost is to have a wider range of choice for the input power (AAs, Li-Po, Solar, etc). I understand that AA's limitations suck, but this maybe the only choice when you're traveling to locations that are underdeveloped and have no access to electricity.

The other thing to note was that the suggestion for v4 was not to use the same LT1302, instead to use another IC that could handle larger amps, such as the one I listed above.

Anyways, I'm not an EE (I wished I was), hence was hoping that someone could come about with a design that we could use (or maybe Adafruit can consider the upgrade anytime now.. ).

[scottinnh]

Thanks for the link to iPad chargers. I think that's just the tip of the iceberg for what's out there in terms of portable of chargers that supports the charging on the iPad. I guess my reason to stick with the MintyBoost is to have a wider range of choice for the input power (AAs, Li-Po, Solar, etc). I understand that AA's limitations suck, but this maybe the only choice when you're traveling to locations that are underdeveloped and have no access to electricity.

The other thing to note was that the suggestion for v4 was not to use the same LT1302, instead to use another IC that could handle larger amps, such as the one I listed above.

Anyways, I'm not an EE (I wished I was), hence was hoping that someone could come about with a design that we could use (or maybe Adafruit can consider the upgrade anytime now.. ).

No problem. I'm no EE either (and wish I was). I did get a little annoyed at some official tersely-worded responses of "the iPad not supported" (which is not a "why"). In the end I assumed it is because it would push the 1302 right to the edge of capabilities and they don't want any liabilities.

The chip you linked looks interesting, but note it is a very tiny chip with many closely spaced leads. There is no convenient through hole DIP package. Sadly, that's the case with lots of new chips. Maybe there are breakout boards for the existing 3113 package sizes, allowing experimentation by novice users?

I expect there is zero demand for kits which expect you to reflow SMD parts (as you've already have learned enough to not want kits).

But don't let this stop you from researching a solution, and trying to build your own charger. All the principles you need to know can be learned from building the MintyBoost and from reading data sheets like the one you found. You just need to find an appropriate forum (not here, this would be too unsupported). Just don't use your iPad as the test subject.. find something that needs 2A 5V but is cheaper if you ruin it (DC fans, etc).

I am going to make a MintyBoost variation to provide 12V power. That's using the LT1302 (not "-5" version) which can max out at 100ma 12v, and eliminating the USB port. I have a garage door opener that uses expensive 12v batteries, and I want to make it work off rechargables.

[Snipeye]

Potential Spam Up there? Not sure.

I've designed a circuit around the lt1308 - it comes in an 8-SOIC package, which is SMD, but not too tiny. I'm trying to get it and a lipo charger to fit on a single board so I can put that board, 3AA's, and a couple lipos into an altoids tin and have an awesomeboost. I suck at routing, though, so I haven't been able to make it small enough yet.

[scottinnh]

Potential Spam Up there? Not sure.

I've designed a circuit around the lt1308 - it comes in an 8-SOIC package, which is SMD, but not too tiny. I'm trying to get it and a lipo charger to fit on a single board so I can put that board, 3AA's, and a couple lipos into an altoids tin and have an awesomeboost. I suck at routing, though, so I haven't been able to make it small enough yet.

No spam, just useful links.

If you search the forum there's about 5 different threads about using MintyBoost with the iPad.
As an "official" answer, people are told the 'Minty does not support the iPad', that's it.
Month's later, someone else asks the same question.
I have to admit, reading some of the earlier answers, I kept asking myself "yeah but WHY..." [cue whiney voice].
I just wanted to see the topic "put to rest".

Limor and Phil have in the past posted some great things about the Voltaic product line, and they have a solution for the iPad and Adafruit does not (at this time).

When it's ready, please DO post your circuit (not here.. start a new thread for yourself). There does seem to be a lot of interest in variations of the MB circuit, even if those variations are not officially supported. Cheers.