diff --git a/docs/emonth2_batterylife_estimate.png b/docs/emonth2_batterylife_estimate.png new file mode 100644 index 0000000..cad774c Binary files /dev/null and b/docs/emonth2_batterylife_estimate.png differ diff --git a/docs/emonth2_power.jpg b/docs/emonth2_power.jpg deleted file mode 100644 index dc5623f..0000000 Binary files a/docs/emonth2_power.jpg and /dev/null differ diff --git a/docs/emonth2_power.png b/docs/emonth2_power.png new file mode 100644 index 0000000..70c61fb Binary files /dev/null and b/docs/emonth2_power.png differ diff --git a/docs/emonth_V1_estimated_batterylife.png b/docs/emonth_V1_estimated_batterylife.png new file mode 100644 index 0000000..bbfdfa0 Binary files /dev/null and b/docs/emonth_V1_estimated_batterylife.png differ diff --git a/docs/power_consumption.md b/docs/power_consumption.md new file mode 100644 index 0000000..8eae7b2 --- /dev/null +++ b/docs/power_consumption.md @@ -0,0 +1,55 @@ +# Power Consumption + +The motivation behind replacing the DHT22 Temperature & Humidity sensor used on the emonTH V1 with the Si7021 Temperature & Humidity sensor on the emonTH V2 was the power saving benefits. + +See the `sensor` folder in the emonth2 repo for a power consumption comparision between the DHT22 and Si7021. + +This document contains real-world emonTH2 power consumption as measured using a multi-meter & scope resistor voltage drop method [explained in previous blog post](http://blog.openenergymonitor.org/2013/07/new-oscilloscope/). + +Here is a scope trace illustrating the emonTH power consumption during a sensor sample: + +![emonth2 power consumption](emonth2_power.png) + +1. Atmega328 wakes up, starts sensors and takes readings: 17.5ms @ 8.4mA + +2. Atmega328 goes back to watchdog sleep but leaves SPI initialised waiting for wait for RFM to initialise: 100ms @ 2mA + +3. RFM69CW transmission: 4ms @ 44mA + +4. Wait for RF transmission to finish: 100ms @ 0.06mA + +5. ATmega328 wakes up to Print data to serial UART: 5ms @ 7.2mA + +Time taken for sample = 17.5 + 100 + 4 + 100 + 5 = **226.5ms** + +Average current per sample = (17.5*8.4) + (100*2) + (4*44) + (100*0.06) + (5*7.2) / 225.5 = 565 / 225.5 = 2.5mA + +After sensor sample is complete the ATmega328 goes back to full watchdog sleep for consuming 0.06mA. This base quiescent consumption includes the quiescent power consumption of the LTC3525 DC-DC converter. See original emonTH hardware blog post for [emonTH DC-DC converter design](https://blog.openenergymonitor.org/2013/10/emonth-update-hardware/). + +Assuming one reading per min (current default) the emonTH is off (sleeping for): number of ms in one min - on time = 60000ms - 225.5ms = 59774.5 + +*** + +To summarise: + +- On current = 2.5mA (average) +- On time = 226ms +- Off current = 0.06mA +- Off time = 59774.5 ms + +[Oregon Embedded online battery life calculator tool](http://oregonembedded.com/batterycalc.htm) can now be used to calculate battery live. Assuming using 2 x AA alkaline batteries @ 2700 mAhr each = 5400 + +![emonth V2 estimated battery life](emonth2_batterylife_estimate.png) + +Given the measured power consumption the emonTh2 is estimated to have a battery life of 7.6 years! + +Plugging in the [power consumption figures from the emonTh V1](http://blog.openenergymonitor.org/2013/10/emonth-update-software-power/) (with DHT22) into the calculator a 1.4 year battery life is estimated. + +![emonth V1 estimated battery life](emonth_V1_estimated_batterylife.png) + +From [real world testing](http://blog.openenergymonitor.org/2015/02/real-world-emonth-battery-life) is been established that the emonTh V1 actually achieves a 8 month battery life. This is 57% less than the estimated figure. + +Assuming the battery life calculator is overestimating by the same amount for the emonTH V2 we can **expect a real world battery life of just over 5 years**, which is not too bad :-p + + +I have setup a battery life test with the emonTh V2 with Si7021 sensor, I will report back in a couple of years :-) diff --git a/hardware/emonTH_V2_0_2_gerbers.zip b/hardware/emonTH_V2_0_2_gerbers.zip index 4c5e212..2b5afee 100644 Binary files a/hardware/emonTH_V2_0_2_gerbers.zip and b/hardware/emonTH_V2_0_2_gerbers.zip differ diff --git a/hardware/emonTH_V2_0_2_gerbers/README.txt b/hardware/emonTH_V2_0_2_gerbers/README.txt new file mode 100644 index 0000000..e829163 --- /dev/null +++ b/hardware/emonTH_V2_0_2_gerbers/README.txt @@ -0,0 +1,12 @@ +# emonTx TH V2.0.2 - Sep 2016 + +- PCB to be 1.6mm thickness +- Solder Resist: Blue +- Finish: HASL + +* No silkscreen should overlap pads +* Check Welsh Daragon logo on the rear is re-produced OK :-) + +glyn.hudson@openenergymonitor.org +Tel: +441248672607 +Mob: +447769871550 \ No newline at end of file