Power Information on Sparkfun ESP8266 Thing board WRL-13231

Development Boards ESP32
1

Hi Guys,

I have one of you amazing Sparkfun ESP8266 Thing board WRL-13231 Microcontrollers.

I’ve been building a Wifi Switch for my LiFx Smart Light Bulbs.

I had all my code working great two months ago, so then modified the code slightly to do some power testing.

I.e. how long will my 2000 mAh battery last.

So what I did was my board wakes up takes a voltage reading, connects to my wifi, turns on the inbuilt led and an external led to indicate were alive, longs my voltage reading on my raspberry pi, then does a shout out to all my four light bulbs to get there state, after 10 seconds it turns off the leds, then another 10 seconds and then shuts down for an 1h. Ok not quite an hr 57 mins approx.

And repeat :slight_smile:

When I first let this run, my battery was at 3.46v, 69 days later and my battery is still on 3.46v WOW.

I want to try and put some kind of warning when it gets to say 10% of low power, I can give an indicator so I know I have to recharge the battery,

What I want to know is what is the lowest voltage the Sparkfun ESP8266 Thing board WRL-13231 will run on ?

I cannot seem to find this information so I thought I would ask yourselves as your’re bound to know this answer.

Thanks for any information you can provide.

Keep up the great products.

Look forward to hearing from you.

Best Regards

Sean Graves

2

Hi Sean.

The [guide says 1.7 volts for a minimum voltage but that’s a lot lower than you’re going to want to run a lipo down too. You might consider switching to a pair of AA batteries as a power source if you want to go that low on voltage. (You might even get a year or more life out of them!) You could make a voltage divider with some high value resistors to monitor battery voltage and connect the output from that to the ADC on the Thing and then do a little math to determine what your battery voltage is from that.

If you’re going to stick with a Lipo, a board like the [LiPo Fuel Gauge might work for you. That can monitor the voltage level of the battery and give you an idea what the state of charge is.](SparkFun LiPo Fuel Gauge - TOL-20680 - SparkFun Electronics)](ESP8266 Thing Hookup Guide - SparkFun Learn)

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Thanks Chris for the information. Most grateful :slight_smile:

Oh god, my eyesight is bad, I didn’t see that minimum voltage in the guide :expressionless:

I had been reading about not letting a Lipo go below 3v. How true, that is another matter.

At present I am taking the voltage reading from the ADC_MODE(ADC_VCC); then reading ESP.getVcc(); three times and taking the average.

It’s more or less been working.

With my current testing its lasted over 70 days with a reading of 3.46v.

So to test the getVcc() , last Friday I added 16 leds via a shift register to drain it a little.

Although my code didn’t want to control the registers (which was working on my nano), it did have the effect of draining the battery a bit and the reading is now at 3.21v

At least the getVcc is working (I know its not accurate but should give an indication)

If I had left as before then I reckon it would have taken 4/6 months to get down to 3.21v.

So I think I’m just going to just set the reading to say when it reaches 3.1 then do a shout out and say “oi give me some power” :slight_smile:

Think that should work.

I’m trying to keep the device as small as possible as I want to make it like a small remote controller.

I will look into the LiPo Fuel Gauge though as that does look interesting.

Thanks again for the advice.

Best Regards

Sean