Solar charging shield Updated 17 Nov

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bplummer
 
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Solar charging shield Updated 17 Nov

Post by bplummer »

I have been happily creating small projects with my Arduino Uno for a while and I finally decided to try something bigger. Well, bigger for me. More complex.

I had a project that would measure distance to an object using a MaxBotix range finder and then turn on one of three LED's based on the distance measured. The project only uses 5v but it draws more than the 20mA at the LED's. I can't provide the power directly from the Arduino so I needed a separate power source. I did some research and found that many projects are powered by a 3.7V Lithium Ion rechargeable battery boosted to 5V. So the power source is going to be a battery boosted to 5V.

I use a few outdoor lights for my house that use a Lithium Ion battery and a Solar panel to recharge it. After researching some more I decided that I should build a charging circuit into my project that can be powered by a Solar panel. So the battery will be recharged by Solar energy.

I also wanted to be able to monitor the battery and go into a low power mode if gets too low. So I wanted to incorporate some kind of fuel gauge as well.

I found many open source projects that were similar to my concept for the battery booster/charger/fuel gauge but none of them fit all the requirements. Ultimately I figured that I would see if I could design the whole thing myself. And this is what I came up with.

You can find the Eagle files here:
https://github.com/JetJaguarXP/shield
Released under the Creative Commons Attribution-ShareAlike 4.0 International License.

It's mainly based on the following open source projects by Adafruit and Sparkfun
https://www.adafruit.com/products/390
https://www.adafruit.com/products/2190
https://www.sparkfun.com/products/13158

I am interested in any feedback that anyone wants to provide. Let me know what you think and if it has a possibility of working. =D

Thank you.
Last edited by bplummer on Thu Nov 19, 2015 2:24 pm, edited 6 times in total.

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adafruit_support_bill
 
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Re: Solar charging shield

Post by adafruit_support_bill »

Nicely done. Thank you for posting.

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poldark
 
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Re: Solar charging shield

Post by poldark »

Interesting, do you know any similar solar charger but with higher input voltage range and still 2-3W?

I want to use these PV modules (http://infinitypv.com/standalone/panels/demopanels) where the voltage can be up to 50V.

Thank you

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bplummer
 
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Re: Solar charging shield

Post by bplummer »

poldark wrote:Interesting, do you know any similar solar charger but with higher input voltage range and still 2-3W?

I want to use these PV modules (http://infinitypv.com/standalone/panels/demopanels) where the voltage can be up to 50V.

Thank you
Sorry Poldark,

Don't know any chargers like that. You may want to check out the Instructable here:
http://www.instructables.com/id/ARDUINO ... ersion-30/
The user deba168 has created some very interesting Solar charge controllers using Arduino to control them. I believe that may be closer to what you are looking for.

Jet

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poldark
 
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Re: Solar charging shield

Post by poldark »

Thanks Bplummer,

I going to try with the Sunny Buddy charger from SparkFun, and place a TVS of 33V at the input.
It makes no sense make a big converter for 2W PV panel.

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bplummer
 
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Re: Solar charging shield

Post by bplummer »

So I have completed the design in Eagle CAD.

Here is the latest schematic. You can find the Eagle files here:
https://github.com/JetJaguarXP/shield

Released under the Creative Commons Attribution-ShareAlike 4.0 International License.

Now I have to figure out how to solder REALLY tiny chips...
Attachments
Newest schematic
Newest schematic
Shield.png (102.86 KiB) Viewed 668 times

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bplummer
 
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Re: Solar charging shield *Updated*

Post by bplummer »

Issues with my design.

1. I completely missed the 3.3V voltage regulator needed for the Fuel gauge chip. I need to add that.
2. I have to look at the configuration of the TPS63060 to identify how it is configured to disconnect the battery. At what voltage will it stop drawing power from the battery. Don't want to kill the battery by drawing too much power from it.
3. Need to connect EN pin on TPS63060 to V+ net. EN pin needs power to turn on the chip.

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Re: Solar charging shield *Updated*

Post by bplummer »

1. Added the voltage regulator.
2. Connected the pin on TPS63060.
3. Looks like I don't have to worry about the configuration for the Buck/Boost chip. The Lipo charger has the battery LBO protection built in so the TPS63060 should never have to deal with it.

Updated the Eagle files on Github. And here's the latest schematic...

Enjoy.
Attachments
shield.png
shield.png (106.84 KiB) Viewed 625 times

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Re: Solar charging shield Updated 11 Nov

Post by bplummer »

Made some changes to the schematic. Moved C1 after the power switch. Moved all components to bottom of board. Updated Eagle files on Github.

Check it out.

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