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Increasing Charge rate of solar lipo charger with minty boos
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Increasing Charge rate of solar lipo charger with minty boos

by scottp3 on Wed Feb 19, 2014 2:35 am

I have assembled both kits successfully, everything works exactly as it is supposed to. However. I have a set of wireless headphones that require 1000 ma to charge, and the solar charger won't go that high. I have read the tutorial (a hundred times) and don't quite understand the equation used when they try to explain how to increase the charge rate. I know I can put in a resistor to do it, but don't quite understand what value to put in. This would complete my project, and I am really wanting to show this thing of a bit.

Thanks.

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Re: Increasing Charge rate of solar lipo charger with minty

by adafruit_support_bill on Wed Feb 19, 2014 8:25 am

If you want to increase the current, you need to decrease the resistance, so you can just solder over the existing 2K.
Soldering another 2K resistor into RPROG will give you 1K total resistance and 1000 mA current draw.

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Re: Increasing Charge rate of solar lipo charger with minty

by scottp3 on Wed Feb 19, 2014 5:12 pm

Thank you. That was the answer I was looking for and I will get to that shortly. You guys are great.

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Re: Increasing Charge rate of solar lipo charger with minty

by juice_dup on Thu Feb 20, 2014 12:38 pm

I am actually working on the same thing here.

Say I got a solar panel to power Minty up, is there any proportion of the Solar wattage to the Minty plus battery output? What would that be and what equations should I be using? If I overlooked any reading material, please point me to a link otherwise I don't mind if you give me all the answers on here :D

- 1A output is great but is it possible to pull 1.5-2A from this guy? Is there any other hacking involved?
“Google can bring you back 100,000 answers. A librarian can bring you back the right one.”
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Re: Increasing Charge rate of solar lipo charger with minty

by adafruit_support_bill on Thu Feb 20, 2014 12:54 pm

The design notes for the solar charger describe how it matches the load to the panel. The load balancing circuit automatically switch current from the charge circuit to the load based on availability and demand.

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Re: Increasing Charge rate of solar lipo charger with minty

by kevinrs on Fri Feb 21, 2014 1:47 am

One limit is going to be that the mintyboost only outputs 5v 500 mA.
Another limit I'm finding is that when charging the LiIon from solar or a DC input, the solar charger, though the chip is rated for up to one amp, heat seems to be a problem. The spec sheet, at section 6.1.1.2 gives an example at 500 mA and tells that thermal regulation will be entered. Adding one of the heatsinks from adafruit might be helping some, but the heatsink and chip are still getting quite hot. I'm waiting on some sheet aluminum I've ordered that I'm going to apply to the back of the circuit board, and apply that to the tin I'm mounting in, so it's a combination heatsink and heat conductor to the tin, rather than use an insulator like double sided tape or an air gap in mounting.
I'm hopeful that the combination of heatsink and aluminum plate will be enough to keep the chip from overheating and turning off.

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