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How to connect "Adafruit Li-Po v.1.2 Charger" to "Arduino Na
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How to connect "Adafruit Li-Po v.1.2 Charger" to "Arduino Na

by NKO5 on Sat Sep 04, 2021 2:39 pm

Hi all.

I need some help from you professionals! The items in question are Adafruit Li-Po Charger 1.2 (link) and Arduino Nano 33 (link). Two questions:

1. I figured I need to use JST-plug (which has two cables (as pictured in Adafruit link I provided); ground and positive) and plug that in to "LOAD" slot of the charger, and then solder the two wires to Arduino. The question is: to which pin holes do I need to solder them to? Black/negative wire goes to GND and red/positive wire to Vin? Or 3.3V?

2. The Charger also has pin holes marked as "STAT 2 1" and my assumption is that I can wire these to to Arduino's digital pins and somehow get charge readings from the li-po battery? Are there any documentation or code examples how to utilize this?

I would really appreciate if somebody could find the time to help a newb like me. Thanks so much!

NKO5
 
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Re: How to connect "Adafruit Li-Po v.1.2 Charger" to "Arduin

by adafruit_support_mike on Thu Sep 09, 2021 8:39 pm

NKO5 wrote:The question is: to which pin holes do I need to solder them to? Black/negative wire goes to GND and red/positive wire to Vin? Or 3.3V?

That board won’t work well with from direct LiPo power.

Vin connects power to the onboard voltage regulator, which needs about 4V to work properly. A LiPo’s voltage will be too low for most of the discharge curve.

The 3.3V pin connects to the microcontroller, whose maximum voltage is about 3.6V. A fully charged LiPo at 4.2V could kill it.

You can connect the LiPo to a TPS62827 3.3V switching regulator:

https://www.adafruit.com/product/4920

Then connect that output to the Arduino’s 3.3V and GND pins.

adafruit_support_mike
 
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Re: How to connect "Adafruit Li-Po v.1.2 Charger" to "Arduin

by NKO5 on Sun Sep 12, 2021 6:40 am

adafruit_support_mike wrote:
NKO5 wrote:The question is: to which pin holes do I need to solder them to? Black/negative wire goes to GND and red/positive wire to Vin? Or 3.3V?

That board won’t work well with from direct LiPo power.

Vin connects power to the onboard voltage regulator, which needs about 4V to work properly. A LiPo’s voltage will be too low for most of the discharge curve.

The 3.3V pin connects to the microcontroller, whose maximum voltage is about 3.6V. A fully charged LiPo at 4.2V could kill it.

You can connect the LiPo to a TPS62827 3.3V switching regulator:

https://www.adafruit.com/product/4920

Then connect that output to the Arduino’s 3.3V and GND pins.


Thanks for taking the time to answer!

I found a different type of charger, the PowerBooster 500 (link), do you think this would work with my project? If I attach my battery to this charger, it will up the volts to 5,2V which would be stable enough for the Vin pin, am I right? And just to make sure I understoond the pins correctly: I should wire the "GND" pin from the charger to Arduino's "GND" pin, and the "5V" pin from the charger to Arduino's "Vin"? Also: there appears to be 3 different GND-pins on the charger circuit, does it matter which one I use? 2 of them look like they are paired together?

NKO5
 
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Re: How to connect "Adafruit Li-Po v.1.2 Charger" to "Arduin

by adafruit_support_mike on Sun Sep 12, 2021 4:09 pm

The PowerBoost 500 will also work, yes.

NKO5 wrote:If I attach my battery to this charger, it will up the volts to 5,2V which would be stable enough for the Vin pin, am I right?

The Vin pin connects to an Arduino's LM1117 voltage regulator, which wants about 1V of wiggle room. You want to use 6V to 9V there.

You can connect a PowerBoost's 5.2V output directly to an Arduino's 5V pin though. The extra 200mV won't cause any problems.

NKO5 wrote:I should wire the "GND" pin from the charger to Arduino's "GND" pin

Yes.

NKO5 wrote:and the "5V" pin from the charger to Arduino's "Vin"?

Use the Arduino's 5V pin instead of Vin, but yes in general.

NKO5 wrote:Also: there appears to be 3 different GND-pins on the charger circuit, does it matter which one I use? 2 of them look like they are paired together?

They're all connected to each other, so you can use any one you prefer.

We put in multiple GND connections so people could have sensible power-and-GND connections for USB input, the LiPo, and the 5V output.

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Re: How to connect "Adafruit Li-Po v.1.2 Charger" to "Arduin

by NKO5 on Mon Sep 13, 2021 6:05 am

adafruit_support_mike wrote:You can connect a PowerBoost's 5.2V output directly to an Arduino's 5V pin though. The extra 200mV won't cause any problems.


By looking at the Arduino Nano 33 schematics it looks to me as if the 5V pin is output only? This site tells me that the 5V pin is disabled by default and I could enable it by soldering these two pads (link), but it would still be output only?

NKO5
 
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Re: How to connect "Adafruit Li-Po v.1.2 Charger" to "Arduin

by adafruit_support_mike on Tue Sep 14, 2021 5:56 pm

I wasn't aware of that, thank you for sharing the link.

In that case, my previous suggestion to use a 3.3V switching regulator would be a better choice.

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Re: How to connect "Adafruit Li-Po v.1.2 Charger" to "Arduin

by NKO5 on Wed Sep 15, 2021 5:49 am

adafruit_support_mike wrote:In that case, my previous suggestion to use a 3.3V switching regulator would be a better choice.


I will try that instead. I assume I can use it in conjuction with the USB LiIon/LiPoly charger - v1.2? As I understand it, the Charger provides 3.7 V (or 4.2 V, which ever is the max for a 3.7 V li-po battery). So the setup would go like this

1. Connect "Load +" from the Charger to "Vin" of the regulator

2. Connect "3V" from the regulator to Arduino 3.3V

3. Connect "GND" from the regulator to Arduino GND

Since there is only one GND pin in the regulator, how do I connect the "Load -" from the Charger? Should I just connect it directly to Arduino's GND instead?


Thanks again for your time!

NKO5
 
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Re: How to connect "Adafruit Li-Po v.1.2 Charger" to "Arduin

by adafruit_support_mike on Fri Sep 17, 2021 10:33 pm

For a step-down converter, the charger's LOAD output will probably work.. the converter turns excess voltage into more current at a lower voltage, so the math works in the charger's favor.

It doesn't favor step-up converters because they draw extra current to generate higher voltage, and need to be connected directly to the LiPo.

NKO5 wrote:Since there is only one GND pin in the regulator, how do I connect the "Load -" from the Charger? Should I just connect it directly to Arduino's GND instead?

Yes. Connect LOAD- to GND.

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