Video How To: Battery Powered Chair Occupancy (Contact) Sensor

[petewill]

@Nca78 Wow, cool. I never got readings down to 2uA. Maybe my multimeter isn't very good or something else...? The main reason I regularly report the battery is to provide a heartbeat as well as reset the sensor if for some reason it could not communicate with the gateway the first time.

Edit: I just re-read your post. I now see that you were saying I could save those additional uA by not using the sleep. That is a good idea. I'm still a little torn on the idea because I like the assurance of the heartbeat. I'll have to think about it. Thanks for sharing though!

[Jic]

That doesn't work to me! :( I am using an arduino clone. I don't Know if that is the problem.

When I use your sketch (an others from Mysensors) my Arduino usage is 30mA, seems like the sleep method doesn't work rigth.

I test with a liltle example from rocketscream/Low-Power and then my Arduino usage is 16uA. Anyone know where the problem may be?

Thanks

[sundberg84]

@Jic did you remove the led and voltage regulator?

[Jic]

@sundberg84

Yes, I have removed both

[mfalkvidd]

@Jic 30mA is way too high even for an unmodified Arduino that is fully awake. There must be something wrong with the Arduino or the measurement.

[sundberg84]

@Jic - you should see in the serial debug if the node is sleeping or not. I have heard there might be a problem with sleep in som recent version. Maybe you investigate this and if nessecaru upgrade to development branch.

[petewill]

@Jic In addition to the great suggestions above also try to disconnect all the sensors and measure again. I had two bad radios that were using way too much power. Bad clones I guess.

[OliverDog]

Thanks for sharing this awesome project...

I want to install all my windows with reed sensors powered by 2AA alcaline batteries and would like they last more than 5 years... and I think your project fits perfectly
How long do those used batteries last?

Did you implement what @Nca78 suggested?

I have already cut LED and Power Regulator from Arduino Pro Mini 3.3v and will change bootloader.
Have you choosen the best (lowest power consumption) bootloader to use?

I would try the MYSBootloader_1MHz.hex from MySensors GitHub.
Would the optiboot_atmega328_01M_009600_NOLED from GertSanders better for low power?

Thanks for the help...

[Nca78]

@OliverDog if you are using 2xAA then 6uA in sleep mode is fine for a few decades.
You can estimate battery life there, if you don't spend your time jumping on your chair it should last the 5 years easily ;)
http://oregonembedded.com/batterycalc.htm

For the bootloaders battery life won't be different, any bootloader using internal oscillator at 1MHz is fine.

[OliverDog]

Great!!! Got it working, but can't measure the consumption...
My multimeter shows always 000.
The sensors is working fine and reporting properly while connected to multimeter, but always 0 current...
Tried 200u, 2000u, 20m and 200m, always reporting zero... Is is that low?

Did I connect something wrong??? (multimeter in series with positive battery pole and circuit line in (Radio+APM+1M ResistorPin3)
Or is my aliexpress multimeter that bad???

[Nca78]

Clean desk you have here @OliverDog this would make my wife dream :D

For the multimeter, no idea. At 200u it should see something, maybe your red wire is in the wrong plug of the multimeter ? Usually it's a different plug for voltage and for current but you can have a different plug for high current (A) and low current (mA) too...

[OliverDog]

I had just cleaned it!!! My wife gave up caring about this desk...:smirk:

I found my multimeter fuse was burned... so I wired its base poles and now I can measure:

Sleeping + Reed Disconnected - most time 6 uA
Sleeping + Reed Connected - most time 9 uA
When sending new status to gateway - 25 - 230 uA (around 140 uA most times)
Sending time was less than 1 second.

2 AA will give me 29 years (battery certainly will die first)
2 AAA - 12 years.
1 CR2032 - 2,5 years.

Thanks for the help...

[Nca78]

@OliverDog when sending to gateway you cannot trust your multimeter. It's probably around 15mA but only during a fraction of a second, and what you read is some kind of average between that and the very low power consumption in sleep mode.