Upgrading MintyBoost to 12V - NEED HELP PLEASE
Moderators: adafruit_support_bill, adafruit

Upgrading MintyBoost to 12V - NEED HELP PLEASE

by MTRigsby on Mon Jan 07, 2013 10:01 pm

Recently, I purchased an 8x AA battery holder, detachable via 9V snap connector. I soldered it to the MintyBoost (not realizing there was a 5V max, and luckily not damaging anything), and realized it didn't charge. I want to be able to solder this holder to the MintyBoost, but obviously need to upgrade it to a higher input. Can someone please tell me what components I need to upgrade, and with what they will be replaced? I'm new to both soldering and circuitry, so any help would be greatly appreciated! Thank you!
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Re: Upgrading MintyBoost to 12V - NEED HELP PLEASE

by adafruit_support_bill on Mon Jan 07, 2013 11:18 pm

What you are asking for is a complete redesign of the MintyBoost. You will need to find a boost converter that works in right voltage range and select the components to build the support circuitry around it. The best I can do is point you to the "Process" page of the Minty tutorial where Ladyada details the whole engineering process. http://www.ladyada.net/make/mintyboost/process.html

But then, if you have an 8xAA battery pack full of alkaline cells, you already have a pretty solid 12V source. What do you need a boost converter for?
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Re: Upgrading MintyBoost to 12V - NEED HELP PLEASE

by MTRigsby on Mon Jan 07, 2013 11:58 pm

adafruit_support wrote:But then, if you have an 8xAA battery pack full of alkaline cells, you already have a pretty solid 12V source. What do you need a boost converter for?


I have the power source, but I currently have no way to convert the power to the 5V USB output... Would I need new resistors, capacitors, diodes, IC chip, and power inductor? As I said before, I'm new to all this, calling me a novice would be stretching it...
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Re: Upgrading MintyBoost to 12V - NEED HELP PLEASE

by john_duh on Tue Jan 08, 2013 5:49 am

Wouldn't one of these do the trick ?

I don't think your input would fall under 6.5V from 8 1,5V batteries. But do get this confirmed by somebody more knowledgeable :?
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Re: Upgrading MintyBoost to 12V - NEED HELP PLEASE

by adafruit_support_bill on Tue Jan 08, 2013 6:40 am

If you need an output voltage lower than the input voltage, then you don't need a boost converter, you need a 'buck' converter. The DC/DC converter linked by john_duh will do the job nicely for loads up to 1A.
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Re: Upgrading MintyBoost to 12V - NEED HELP PLEASE

by nginx on Wed Jan 09, 2013 10:41 am

If you are gonna use NiMH batteries, make sure you don't let the cumulative voltage of the battery pack drop below 7.2V or else you run the risk of cell reversal if all cells are not of equal age, make, capacity and charge.
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