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mintyboost getting very hot!
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Please be positive and constructive with your questions and comments.

mintyboost getting very hot!

by Cew27 on Fri Feb 27, 2009 4:24 pm

right guys just built mintyboost 1.2 and it isnt working and it is getting very hot!, no short circuits, capacitors polarity is correct, other components look fine. so what could it be?
the only thing i can think of is that my diode is in wrong (even though the diagram matches) the leg colors were inverted i think
thanks alot
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Re: mintyboost getting very hot!

by adafruit on Tue Mar 03, 2009 12:06 am

you should post a CLEAR PHOTO of the top and bottom

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Re: mintyboost getting very hot!

by Cew27 on Tue Mar 03, 2009 4:16 am

turns out i had v1.2 boost chip and caps, replaced with v2.0 cap and chips and all is going smoothly
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Re: mintyboost getting very hot!

by Yammerton on Thu Jan 09, 2014 9:26 pm

I know that the previous users issues have been somewhat resolved but rather than starting a new thread I'll post here.

I've soldered everything in place and tested a solid 4.94 volts. Not only does the chip get VERY hot the C4 capacitor gets quite hot and looks like it's bulged. After leaving my iPhone 5S connected for a few minutes the MintyBoost was charging my phone but the AA batteries were get pretty warm and the USB end of the cable was getting hot as well. I've attached a couple of photos that hopefully identify any potential issues unless all of this is pretty normal. Any thoughts? Oh one last thing, I have the red wire soldered to + and black to -, but this results in the wires being crossed, seems like an odd setup from an aesthetics point of view.

photo 1.JPG
photo 1.JPG (523.9 KiB) Viewed 1446 times

photo 2.JPG
photo 2.JPG (544.68 KiB) Viewed 1446 times

photo 3.JPG
photo 3.JPG (542.82 KiB) Viewed 1446 times
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Re: mintyboost getting very hot!

by adafruit_support_bill on Thu Jan 09, 2014 9:52 pm

It is normal for the chip to get very hot: http://learn.adafruit.com/minty-boost/f-dot-a-q
The maximum temperature for the mintyboost chip is over 100 degrees C, that is hotter than boiling water. If you are worried, lick your finger (a little) and touch the tip of your finger to the top of the LT1302 chip. If you don't hear a sizzle (of the water boiling away), it's just fine.


Other components will get warm also - including the batteries. Do you have a photo that shows the bulge in C4?

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Re: mintyboost getting very hot!

by Yammerton on Thu Jan 09, 2014 9:59 pm

Just the photos posted. It may be difficult to see but the top of C3 is sitting flat but the top of C4 definitely has some curvature. If this is all normal then I'm not concerned.

Thanks for the quick reply though. This is why I love Adafruit!
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Re: mintyboost getting very hot!

by adafruit_support_bill on Thu Jan 09, 2014 10:12 pm

C4 does seem to be slightly domed on top. Hard to say if it is abnormal or not. The most common cause of electrolytic capacitor overheating is when they are installed backwards, but yours appears to be installed correctly. And the mintyboost does appear to be working normally. If C4 shows any further signs of bulging, let us know.

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Re: mintyboost getting very hot!

by Yammerton on Thu Jan 09, 2014 10:23 pm

I'll keep an eye on it. I've left my phone charging for about 40 minutes, I went from 22% charge to 33%, it stopped and the phone is now giving me an "Accessory may not be accepted" message.
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Re: mintyboost getting very hot!

by adafruit_support_bill on Thu Jan 09, 2014 10:32 pm

I've left my phone charging for about 40 minutes, I went from 22% charge to 33%, it stopped and the phone is now giving me an "Accessory may not be accepted" message.

Sounds like you batteries are drained. Modern smart-phones like the 5s have pretty big batteries in them. Much more than can be fully charged with a pair of AA cells. Check our battery recommendations here: http://learn.adafruit.com/minty-boost/batteries

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Re: mintyboost getting very hot!

by Yammerton on Thu Jan 09, 2014 10:52 pm

Ah yes, only 2.6 volts at the batteries, I was testing at the USB which was still giving me 4.9 volts but I assume that is just residual stored energy. Thanks for all the help.
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Re: mintyboost getting very hot!

by adafruit_support_bill on Fri Jan 10, 2014 6:16 am

The MintyBoost will do its best to boost with whatever the input voltage is. But the efficiency goes down as it has to work much harder with lower voltages. At some point it can't keep up with the 500mA current that the iPhone wants and the phone will drop out of charge mode.

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Please be positive and constructive with your questions and comments.