Battery life issue

Question

My device eats its battery in 12 hours or so - not weeks as intended. I verified with Arduino Serial Monitor that it goes to sleep correctly. Is there anything else I can check? I don't have a voltage monitor at hand, so something software-based would be great.

I found hints of a testing mode that might cause the device to never go to sleep - is there more documentation on this? It's mentioned in this similar, incomplete question: https://support.thingpulse.com/494/battery-defect-on-espaper-plus-kit?show=494

Answer 1

You could shorten the update time (or wait) and monitor the Serial port to see if it wakes from sleep after reporting it entered sleep. this will help to determine if the code is running correctly. If it does not wake, then the problem can be taken further.

Do you see a gradually reducing battery voltage across the duration of 12-hour battery life? e.g. 4.2 then 4.0 then 3.8 then 3.6 or a sudden change in voltage?

Comments

I believe something is indeed wrong with the times wake up. I only refreshed the decice manually so far because I only need updates once every 24h, so it never triggered itself. Now that I set it to update every 5 minutes, it does not change at all.

How can I investigate further? The voltage is dropping gradually and linearly.

Answer 2

Hi Johannes

Have you read Marcel's post about max deep sleep? https://thingpulse.com/max-deep-sleep-for-esp8266/

It's a good introduction to the topic of sleep. In theory it could be many things:

• Bad WiFi reception, which causes a long time to connect and thus drains the battery
• A bad battery. You have two modules. Do both modules have the same issue? It's highly unlikely that it is the battery if both react exactly the same
• Too long/ too short sleep cylce
• Problem with the code: did you change the "stock" code from our Github repo?
• Some flaw in your setup: do you actually disconnect the USB-To-Serial programmer after programming? If you would disconnect the USB cable but leave the programmer in the slot this would drain the batteries much faster

These are just a few ideas. Sadly it's really hard to give a remote analysis of the problem...