ESP8266 Community Forum

- Sun Apr 03, 2016 8:42 am #44731

If I stick pull ups on there then that will increase the current draw surely?

Not really ! When those pins are still in input mode, the current drawn is "Iil" (Input Leakage Current) mentioned in the specs at 50nA.
Of course, if you switch for example GPIO2 as output and provide a LOW at this output, then the consumption will follow Ohm's Law : 3V/10K=0.3mA. But this is only worst case scenario, because why you would leave LOW state forever on this GPIO ...

- Mon Apr 04, 2016 12:00 pm #44810 Mu multimeter is not behaving very well. If I put it in the 200mA range and do a quick cycle, my circuit draws around 75mA for 8 or 9 seconds, then the meter says it drops to 0.0 (or 0.1 occasionally) when it is asleep. Unfortunately if I try and use a lower range, like 2000uA for example, it starts at "1" (obviously) but it never seems to recalibrate down to the sleep current

But anyway, if it's only drawing 75mA for 10 seconds and then something south of 100uA for 10 minutes I reckon a 2000mAh battery should last around a year:

75mA for 10 seconds into an hour = 75*10/3600 = 0.208
100uA for 660 seconds into an hour = 0.0183 (My sleep time is actually 11 minutes)

Total draw per hour = 0.226

From a 2000mAh battery = 2000/0.226 = 8824hours or 367 days.

Is my maths near enough right?

I'm thinking I might have got some rubbish batteries...

- Mon Apr 04, 2016 12:15 pm #44814 Gah - missed a bit sorry.

There are around 5.4 cycles per hour ((660+10)/3600) so factoring that in I end up with ~68 days.

- Mon Apr 04, 2016 12:38 pm #44818

Not really ! When those pins are still in input mode, the current drawn is "Iil" (Input Leakage Current) mentioned in the specs at 50nA.

Interesting - thanks! OK - I will add in the pull ups then. Bit I don't think it will make much difference to my power problem. As I said, the deep_sleep/wake cycle works just fine...