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Mini LiPo Charger with Arduino
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Mini LiPo Charger with Arduino

by FloriR on Sat Feb 27, 2021 4:36 am

Hello,

I have two questions regarding the "Adafruit MicroLipo and MiniLipo Battery Chargers":

1. The +5V pin is an input pin right?? If a voltage of +5V can be applied there, I would like to use this as a possibility to charge my battery (LiPi 2000 mAh) via a solar panel. Is this possible, or is there anything to consider here?

Is it possible to show feedback about the battery's state of charge on a display (scale 0 to 100 %) via the Adafruit component?How could I do this, preferably only on the code side? I would be very grateful for any tips!


Many greetings
FloriR

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Re: Mini LiPo Charger with Arduino

by adafruit_support_bill on Sat Feb 27, 2021 9:23 am

Yes. The 5v pin can be used as an input on the mini and micro lipo chargers. However, for solar panel use, you would be better off with one of these: https://www.adafruit.com/product/4755

For monitoring the state of charge, we have a 'fuel gauge' board here: https://www.adafruit.com/product/4712
https://learn.adafruit.com/adafruit-lc7 ... r/overview

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Re: Mini LiPo Charger with Arduino

by FloriR on Sat Feb 27, 2021 11:22 am

Hello,

thanks for the quick feedback. I'll describe my procedure again in more detail so that I'm sure before ordering:

I want to power my Arduino with a battery that I can charge once via solar, but also externally via a plug (USB or similar). I would like to have only the interface with the USB for external charging visible to the outside and offer it as an "intervention option", the rest is hidden in a housing.
The Arduino should always run, even if the battery is charged in parallel or the sun is shining and the solar cell is supplying power. When the sun is shining, the battery should also be charged in parallel with the surplus, so it mainly serves as a buffer for the night.

The connection of the solar panel should therefore be integrated into the charging circuit via a JST connector if possible; as mentioned, only the interface for external charging should be routed to the outside.
The way to the Arduino is via a step-up converter to +5V voltage, the battery runs on 3.7V logic.
Would you have a wiring suggestion for me on how to connect this cleverly with the components you suggested? The charging module impresses me because of the high charging power, my current charger only charges with 500 mA.
If it is possible with the BQ24074 module to place the battery in one slot and connect a suitable solar panel via the other JST connection, it would be a good option, but I still need to know where to integrate the battery monitor in my chain.

I would also like to know whether the library of the battery monitor also supports a 5000 mAh battery and not only up to 3000 mAh?



I would be very grateful for any feedback.

Many greetings
FloriR

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Re: Mini LiPo Charger with Arduino

by adafruit_support_bill on Sat Feb 27, 2021 11:43 am

The BQ24074 charger can accept input from USB as well as from a solar panel. The charge rate can be as high as 1.5A - assuming that power is available from one of the input sources. Do check you battery specs for the maximum safe charge rate.

The battery would connect to the JST BATT jack. Your load would connect the JST LOAD OUT jack. The charger is capable of powering the load while simultaneously charging the cell.

If using the fuel gauge, it would be wired between the charger and the LiPo cell. The cell size selection in the library helps the chip to more accurately estimate the charge level. It is based on the table on page 11 of the datasheet and is valid for the cell types that we carry in the store. If you are using a higher capacity pack composed of multiple cells, you should select the option closest to the capacity of the individual cells. For example, the 6600mAh pack is composed of 3x 2200mAh cells wired in parallel. So you should select the 2000mAh option. https://www.adafruit.com/product/353

https://cdn-learn.adafruit.com/assets/a ... 1599248750

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Re: Mini LiPo Charger with Arduino

by FloriR on Sat Feb 27, 2021 12:36 pm

Ok I use the JST BATT jack for the battery and connect the LC709203F in between. I use the JST jack for my load, that is clear.

Is it now possible to solder the two cables of the solar panel directly to the pins and thus supply the device with power and charge the battery in parallel, as you said
"The charger is capable of powering the load while simultaneously charging the cell."
?
Then it should also be possible to use the USB port or the socket for charging the battery in parallel if I want to charge it externally. Or does this cause complications when several devices are connected?Secondly, which charging method is preferred, USB/jack or soldered solar panel?

The picture is just an example of the major connections, some are missing (like the wiring of the monitor to the Arduino etc).



Thanks for the feedback!
Attachments
Project solar panel.png
Project solar panel.png (37.51 KiB) Viewed 488 times

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Re: Mini LiPo Charger with Arduino

by adafruit_support_bill on Sat Feb 27, 2021 2:15 pm

Is it now possible to solder the two cables of the solar panel directly to the pins

There are no breakout pins for the solar input. The solar panel should be connected via the barrel jack.

Then it should also be possible to use the USB port or the socket for charging the battery in parallel if I want to charge it externally. Or does this cause complications when several devices are connected?

Both the USB and the Barrel jack inputs are diode protected. If two power sources are connected, the one with the highest voltage will be used. In either case, there is no problem powering the load while charging.

Secondly, which charging method is preferred, USB/jack or soldered solar panel?

USB will provide a steady 5v input. The output of the solar panel will vary widely.

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Re: Mini LiPo Charger with Arduino

by FloriR on Sat Feb 27, 2021 3:27 pm

There are no breakout pins for the solar input. The solar panel should be connected via the barrel jack.


I don´t understand this, I mean the soldering pins in my photo. Or what is the purpose of these soldering pins? Sorry if I have expressed myself unclearly... I want to use those for the solar panel input wires as connection instead of the barrel jack!

USB will provide a steady 5v input. The output of the solar panel will vary widely.


Ok, is it also compatible with a 5,5 V solar panel or just between 6 to 10 V?
Attachments
soldering pins.png
soldering pins.png (163.83 KiB) Viewed 479 times

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Re: Mini LiPo Charger with Arduino

by adafruit_support_bill on Sat Feb 27, 2021 4:05 pm

I don´t understand this, I mean the soldering pins in my photo. Or what is the purpose of these soldering pins?

"OUT" is an output pin. Not an input pin. See the documentation here: https://learn.adafruit.com/adafruit-bq2 ... -3071583-2

Ok, is it also compatible with a 5,5 V solar panel or just between 6 to 10 V?

A 5.5v panel will work - but not quite as well as a 6v panel of similar wattage rating. Panel voltages are 'nominal' and usually based on exposure to direct full sun. The charger needs a minimum voltage input of around 4.5v to charge the cell. A 5.5v panel will drop below that in marginal conditions faster than a 6v panel will.

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Re: Mini LiPo Charger with Arduino

by FloriR on Sat Feb 27, 2021 4:19 pm

Ah I messed up with the Load Out in my wiring, sorry for that.

So solar input is only via the barrel jack possible with the BQ24074. As I said, I only want to lead the connection for the USB plug out of the housing. From my point of view there are two possibilities:
1. A USB plug/cable/connector as a bridge to my enclosure.
2. Solder the USB socket away and move it to the enclosure and connect it by cable. Is this possible?

Which of the possibilities would you recommend or do you see another chance? Or do you have a suitable component for me at Adafruit?

Thank you for your super quick answers, this helps me a lot and I am very grateful for it!

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Re: Mini LiPo Charger with Arduino

by adafruit_support_bill on Sat Feb 27, 2021 4:46 pm

We have a number of USB panel-mount extensions: https://www.adafruit.com/?q=usb+panel&sort=BestMatch
You could also de-solder the barrel jack and solder your panel leads to the pin holes for that.

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Re: Mini LiPo Charger with Arduino

by FloriR on Mon Mar 01, 2021 5:37 am

Thanks a lot for your feedback!

One more question:

What does the BQ24074 do when the battery is full and the solar panel is still "supplying power", where does this power go? Is there then a cut-off integrated here or does this simply lead to heating through a resistor or similar?

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Re: Mini LiPo Charger with Arduino

by adafruit_support_bill on Mon Mar 01, 2021 6:41 am

If there is a load, it will be directed to the load. If there is no load, then the only current flow is a few milliamps for the indicator LEDs and standby current for the BQ24074 chip.

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Re: Mini LiPo Charger with Arduino

by FloriR on Wed Mar 17, 2021 10:32 am

Thank you Bill.

Another question about the LC709203F Fuel Gauge: I have ordered it and it's now running with the BQ24074 and everything works so far. My connected LiPo battery also charges cleanly between 3.6V and 4.2V, so everything fits. The question refers to the output of the battery charge in %, this seems to me relatively inaccurate and also fluctuating (when switching the project on and off, the value varies), despite constant voltage. I display this value in the serial monitor.Is there another way to make this value more stable instead of just outputting it through "lc.cellPercent(), 1"?
The capacity of the battery is edited correctly.

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Re: Mini LiPo Charger with Arduino

by adafruit_support_bill on Wed Mar 17, 2021 10:54 am

Let's start with some photos of your setup so we can everything is right there.

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Re: Mini LiPo Charger with Arduino

by FloriR on Wed Mar 17, 2021 11:21 am

The setup works perfectly, it's just a question of how I can get the library to provide a reliable indication of the corresponding battery charge in percent for each voltage level. It Displays the percentage, but when the battery is charged the Level is inaccurate.
Or is it "normal" that the fiel gauge is not 100% corresponding to the SOC and is slightly variable?

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Please be positive and constructive with your questions and comments.