Minty Boost, request for review

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dacnc
 
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Minty Boost, request for review

Post by dacnc »

So, I and my son both got kits. He's had first crack at his and so we're in the process of testing (it's not in the tin yet.) I'm pretty sure we followed the tutorial (quit a good one actually) and I've been reading the other posts to see what they've run into. However I think we've hit the stage where a review would be helpful. I've posted picture of front and back and one of my testing (input on if I'm doing it right?!) Testing for continuity, with battaries in, I'm getting right around 2 for red/black, red/pin1, etc.) When we plug in an ipod we're still getting an 'unsupported' message (and we've already 'fused' the two suggested usb pins.) Suggestions on next steps?
minty boost front
minty boost front
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Minty boost back
Minty boost back
mb_back2013-05-25.jpg (150.99 KiB) Viewed 1868 times
mb testing
mb testing
mbtest2013-05-25.jpg (620.19 KiB) Viewed 1868 times

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adafruit_support_bill
 
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Re: Minty Boost, request for review

Post by adafruit_support_bill »

I'm getting right around 2 for red/black, red/pin1, etc.)
What do you get between pins 1 and 4 of the USB socket?
Your input voltage looks low. Fresh Alkalines should be more than 3v. Freshly recharged NiMH (eneloop etc) should be 2.4v or more. See our battery recommendations here: http://forums.adafruit.com/viewtopic.php?f=15&t=22377

dacnc
 
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Re: Minty Boost, request for review

Post by dacnc »

Between pins 1 & 4 of the USB socket I'm getting 5.

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adafruit_support_bill
 
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Re: Minty Boost, request for review

Post by adafruit_support_bill »

Between pins 1 & 4 of the USB socket I'm getting 5.
And what happens to that when you plug the phone it? I suspect it drops a bit. Since you input voltage is just over 2v, I suspect that your batteries are fairly weak and the output will sag under load.

dacnc
 
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Re: Minty Boost, request for review

Post by dacnc »

When I plug the phone in the the voltage at the red/black leads is 2.2v.
The voltage at the usb plug pins 1 & 4 remains at 5v.

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adafruit_support_bill
 
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Re: Minty Boost, request for review

Post by adafruit_support_bill »

When I plug the phone in the the voltage at the red/black leads is 2.2v.
That is too low for either alkaline or NiMH battery chemistries. You need to use fresh batteries.
The voltage at the usb plug pins 1 & 4 remains at 5v.
Is that before or after the device refuses to charge? If the output voltage drops when the device attempts to enter charge mode, the device will exit charge mode and stop drawing current.

dacnc
 
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Re: Minty Boost, request for review

Post by dacnc »

OK - these are relatively fresh (the only thing I've used them for is to try out the minty boost)
but they are an 'off' brand. Let me get some duracell or energizer and retry.

dacnc
 
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Re: Minty Boost, request for review

Post by dacnc »

I've put in a fresh set of duracells. I'm still getting 2.2v at the leads when an ipod is plugged in with 5v
between pins 1 & 4 of the usb plug. But at least with these battaries the ipod is not fluctuating/rejecting
the minty boost (and the minty boost is hot, when it wouldn't do before).

So isn't the minty boost supposed to take battaries that have been 'run down' by other stuff (headlamp for instance)
and then make like an energy vampire and suck _all_ the remaining energy out (i.e. take batts that are at 70% and take them all the way down to 0%)?

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adafruit_support_bill
 
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Re: Minty Boost, request for review

Post by adafruit_support_bill »

So isn't the minty boost supposed to take battaries that have been 'run down' by other stuff (headlamp for instance)
and then make like an energy vampire and suck _all_ the remaining energy out (i.e. take batts that are at 70% and take them all the way down to 0%)?
No, that is not what it is designed to do. You may be thinking of the "joule thief" circuit which is capable of "driving light loads".

The MintyBoost is designed to charge phones which are definitely not "light loads". As a "boost converter" it converts a lower voltage to a higher voltage. To generate the 5v @500mA that is expected by the phone from a 2.2v input voltage, it needs to have substantially more than 1A available (the laws of physics don't allow for a free lunch here). "Run-down" batteries are not capable of supplying that kind of current. Even fresh generic cells may have difficulty delivering that kind of current for long. That is why we recommend cells designed for high-drain usage.

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