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Charging LED on Feather HUZZAH blinking despite no bat
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Please be positive and constructive with your questions and comments.

Charging LED on Feather HUZZAH blinking despite no bat

by valenceelectron on Sat Aug 04, 2018 2:17 pm

Hi there! Newbie here.

I've developed a program for a "Feather HUZZAH with ESP8266". Testing/developing was done with it attached to my computer via USB.
Now that I'm finished I've attached the USB cable to a regular 5V power supply and the feather works well, however, the charging status LED is constantly blinking. At first I was worried this might indicate a problem but it seems to work so far. The constantly blinking LED is a little annoying though. Oh and of course there is no battery attached.
All my wiring is a connection to a BEM680 breakout (I2C) and GPIO16 to RST for deep sleep.

Is there a problem because the LED is blinking with no battery attached? Is there a meaning to it?
And ultimately: how to turn it off?

Thanks in advance!

valenceelectron
 
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Re: Charging LED on Feather HUZZAH blinking despite no bat

by adafruit_support_mike on Sat Aug 04, 2018 11:06 pm

It's normal for the charging LED to blink when no LiPo is connected. It just means the LiPo charger is reacting to random voltage fluctuations on the BAT pin due to things like parasitic current in the components and static charge accumulation.

Any time BAT goes below the threshold for starting a new charge cycle, the LiPo charger will try to send current to the pin, and that will bring the pin up to the correct shutoff voltage almost instantly. Then the charger shuts down and lets the pin voltage drift again.

It's harmless.

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Re: Charging LED on Feather HUZZAH blinking despite no bat

by eeriedescent on Fri Aug 02, 2019 8:18 am

Harmless or not, how can I turn this off? I find it pretty annoying as well.

Can I short this to a GPIO pin pulled high?

eeriedescent
 
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Re: Charging LED on Feather HUZZAH blinking despite no bat

by adafruit_support_mike on Sat Aug 03, 2019 12:36 pm

You can connect a 10uF capacitor between BAT and GND. The LiPo charger will charge that to 4.2V, and the capacitor will hold the voltage stable against random leakage currents.

A GPIO pin will only take the BAT voltage to 3.3V, which is about 0.9V too low. Connecting to 5V would damage the LiPo charger's output, and trying to make a 4.2V voltage divider would be iffy. LiPo chargers have to hit their target voltage within about 4mV to operate safely.

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Re: Charging LED on Feather HUZZAH blinking despite no bat

by eeriedescent on Mon Aug 05, 2019 9:41 am

That makes sense. Thank you!

eeriedescent
 
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Re: Charging LED on Feather HUZZAH blinking despite no bat

by tinkerdave on Tue Oct 15, 2019 10:41 am

Hi there,

This may be the wrong thread for dealing with the charge LED flicker issue for other controller boards but I'm currently having this issue using a Feather nRf52 Bluefruit LE without a battery.

I tried the cap solution above, but all it did was delay the flicker until the cap charged, then it starts to flicker again. Looking at the Feather nRF52 schematic, I see there is already a 10mF cap connected between VBAT and GND. I tried putting a 1 meg resistor between VBAT and GND, and the flicker stops. What I don't know is if this causes any harm to the LIPO charger chip long term. I assume the current through that resistor will be extremely small , so I'm not too worried, but I really don't know. Does anyone have any insight?

Thanks.

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Re: Charging LED on Feather HUZZAH blinking despite no bat

by adafruit_support_mike on Wed Oct 16, 2019 12:47 am

That will work, and won't hurt anything. The 1M resistor just gives the LiPo charger a few microamps worth of DC connection to GND.

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Please be positive and constructive with your questions and comments.