search

PaulRB / WemosSensor

Indoor Temp, Humidity and/or Barometric pressure sensor using Wemos D1 Mini
43 stars 6 forks source link

Battery directly to sensor? #2

Closed Albin76 closed 7 years ago

Albin76 commented 7 years ago

Hi. I absolutely love your setup and I have learned loads from studying your code (and your insights on the Wemos forum) and have made a sensor by your instructions that work fine.

One thing I do not follow and would like to understand is the connection of the sensor directly to battery. Most sensors for example BMP280 have a max VCC that is lower than the max battery voltage (BMP280 is 3.6V according to datasheets) and a fully charged 10440 is approx 4.15V. Connecting them directly to battery and not through the Wemos 3.3 should be more efficient since no conversion losses but is it safe/functional?

Can you explain please how you have reasoned?

PaulRB commented 7 years ago

I should have explained in more detail. The sensor breakout boards I use all have their own 3.3V regulator on board, such as this one: http://www.ebay.co.uk/itm/BME280-Digital-Temperature-Humidity-Barometric-Pressure and this one: http://www.ebay.co.uk/itm/1pcs-HTU21D-Temperature-Humidity-Sensor-Breakout

PaulRB commented 7 years ago

If using a sensor board without its own regulator, you could use the 3.3V pin from the Wemos as you suggested.

Thanks for your feedback and appreciation!

Albin76 commented 7 years ago

Thanks. That explains a lot. I Will see if I have a regulator on mine and connect thouse directly and by the 3.3V on the others then.

Curious about one thing. May i ask how many days you manage between charges on a 10440 (and at what sample rate of course)?

I myself have at best 15 days between charges (4.15 to 3.45V) and have a reading every 15 minutes and use wifi manager.

sön 9 juli 2017 kl. 12:13 skrev Paul notifications@github.com:

I should have explained in more detail. The sensor breakout boards I use all have their own 3.3V regulator on board, such as this one:

http://www.ebay.co.uk/itm/BME280-Digital-Temperature-Humidity-Barometric-Pressure and this one: http://www.ebay.co.uk/itm/1pcs-HTU21D-Temperature-Humidity-Sensor-Breakout

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub https://github.com/PaulRB/WemosSensor/issues/2#issuecomment-313911063, or mute the thread https://github.com/notifications/unsubscribe-auth/AZdN4XWPjDD7cEIVl1z6gxeKqxzn-b_Iks5sMKfkgaJpZM4NmDVp .

PaulRB commented 7 years ago

I get around 21 days between charges. Sample rate is 15 mins. The Wemos wakes for around 5 or 6 seconds. It has a fixed ip address on my home network, so does not need to wait for DHCP to allocate an address. The battery voltage drops to around 2.6~2.8V before it stops working.