USB/DC Lithium Polymer Charger Question

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dbens293
 
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USB/DC Lithium Polymer Charger Question

Post by dbens293 »

I recently purchased this product USB/DC Lithium Polymer battery charger 5-12V - 3.7/4.2v cells and i noticed that it says on the bottom of the board that it can be used to charge up to 4.2V or 8.4 for a 2 cell Lipo. I also saw this on the EagleCad schematic (https://www.adafruit.com/datasheets/mcp73861.png), but i am unable to find any other information on how to make this happen. Could someone please explain the different charging "modes" and how to change them?
Thanks

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adafruit_support_bill
 
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Re: USB/DC Lithium Polymer Charger Question

Post by adafruit_support_bill »

2-cell charging requires a different chip than what is on the board now. There are issues with doing this safely - depending on the battery pack. We recommend 'balance charging' and should have a tutorial for that up soon.

dbens293
 
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Joined: Tue Feb 05, 2013 4:09 pm

Re: USB/DC Lithium Polymer Charger Question

Post by dbens293 »

I also have a 9 Volt, 1.5 Watt solar panel that i purchased from RadioShack and I have connected this to the input of the charger after running it through a Schottky diode. The light comes on saying that it is charging, but the batteries are charging very slowly if even charging at all. The open circuit voltage of the panel is around 10 volts and the short circuit current is a little under 150 mA. I also have a 3300 uF cap on the output of the panel as to steady the input voltage into the charger. Do you see any problems here?

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adafruit_support_bill
 
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Re: USB/DC Lithium Polymer Charger Question

Post by adafruit_support_bill »

As long as the panel can keep the voltage up, the charger should work. In practice, this is hard to do for a complete charge cycle. A passing cloud can cause the voltage to collapse and start the charge cycle all over again. The design notes for the solar charger discuss some of the special considerations for charging from a solar panel: http://learn.adafruit.com/usb-dc-and-so ... sign-notes

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