Power consumption problem when the AP is not avaliable

Harold L.
Posts: 26
Joined: Thu Dec 18, 2014 3:24 pm

Power consumption problem when the AP is not avaliable

Postby Harold L. » Mon Aug 10, 2015 4:27 pm

Hi! We are designing a battery powered device on the top of ESP8266, and found there is abnormal high current during some situation.

Firstly set ESP8266 to station mode. The total current was 70mA. Once in a while went up to 100mA, it's OK!

But in both situations below, the total current went up to an abnormal high value: 130mA

1. When AP is not available. e.g. power off your router, or take ESP8266 out to the streets;
2. call 'wifi_station_disconnect'


We'd like to save power when WIFI is not available since our device is powered by battery. Wish you can give me some help, it really matters to us, thanks!

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kolban
Posts: 131
Joined: Tue Jun 16, 2015 1:09 pm
Location: Fort Worth, Texas, USA

Re: Power consumption problem when the AP is not avaliable

Postby kolban » Mon Aug 10, 2015 9:31 pm

Howdy,
If I read the datasheet available here:

download/file.php?id=520

It seems to say (see Table 4) that the current draws you mention are normal....

I could be reading the table incorrectly ....

Neil

Harold L.
Posts: 26
Joined: Thu Dec 18, 2014 3:24 pm

Re: Power consumption problem when the AP is not avaliable

Postby Harold L. » Tue Aug 11, 2015 12:02 pm

kolban wrote:Howdy,
If I read the datasheet available here:

download/file.php?id=520

It seems to say (see Table 4) that the current draws you mention are normal....

I could be reading the table incorrectly ....

Neil


Thanks for your reply, but I think the table 4 only mentions the situation of Txing and Rxing packets. In my first situation, the AP is NOT exist at all, and no packets are sending or receiving.
In that scene, we hope only CPU are working -- recording data silently -- as long as possible.
Attachments
t4.png

ESP_Alfred
Posts: 56
Joined: Mon Nov 10, 2014 7:31 pm

Re: Power consumption problem when the AP is not avaliable

Postby ESP_Alfred » Fri Aug 14, 2015 9:53 pm

Harold L. wrote:Hi! We are designing a battery powered device on the top of ESP8266, and found there is abnormal high current during some situation.

Firstly set ESP8266 to station mode. The total current was 70mA. Once in a while went up to 100mA, it's OK!

But in both situations below, the total current went up to an abnormal high value: 130mA

1. When AP is not available. e.g. power off your router, or take ESP8266 out to the streets;
2. call 'wifi_station_disconnect'


We'd like to save power when WIFI is not available since our device is powered by battery. Wish you can give me some help, it really matters to us, thanks!


Dear Harold L,
Could you tell me how get the value "130mA" , and how long this current exist.
Ths

Harold L.
Posts: 26
Joined: Thu Dec 18, 2014 3:24 pm

Re: Power consumption problem when the AP is not avaliable

Postby Harold L. » Mon Aug 17, 2015 11:26 am

ESP_Alfred wrote:
Dear Harold L,
Could you tell me how get the value "130mA" , and how long this current exist.
Ths


Hi! Any of the cases below would lead you to the abnormal high current:
1. Power off your router after ESP8266 connected as a station, you will see the abnormal high current. In my situation, it continues as long as the disappearance of your router's signal.
2. Power off your router, then power on a ESP8266(configed as a station), you will also see it happens.
3. call 'wifi_station_disconnect' after ESP8266 connected as a station. the abnormal high current continues until you call 'wifi_station_connect'

Thank you!

Harold L.
Posts: 26
Joined: Thu Dec 18, 2014 3:24 pm

Re: Power consumption problem when the AP is not avaliable

Postby Harold L. » Mon Aug 17, 2015 11:36 am

Btw, you should focus on the relative value, the rising-edge of the current when power off your router(130mA - 70mA = 60mA) instead of the absolute values, because there exists some bias-current caused by things like LCD screen, external ADCs in my measurement.

Surely, those things would not be the reason of this problem since they just have not way to be informed when the router is powering on/off.

ESP_Alfred
Posts: 56
Joined: Mon Nov 10, 2014 7:31 pm

Re: Power consumption problem when the AP is not avaliable

Postby ESP_Alfred » Tue Aug 18, 2015 11:18 am

current.jpg
Harold L. wrote:Btw, you should focus on the relative value, the rising-edge of the current when power off your router(130mA - 70mA = 60mA) instead of the absolute values, because there exists some bias-current caused by things like LCD screen, external ADCs in my measurement.

Surely, those things would not be the reason of this problem since they just have not way to be informed when the router is powering on/off.


Dear Harold L.
The table 4 is right.
When we disconnect from AP, we will send packets. So "Tx" been opened.

ESP_Alfred
Posts: 56
Joined: Mon Nov 10, 2014 7:31 pm

Re: Power consumption problem when the AP is not avaliable

Postby ESP_Alfred » Tue Aug 18, 2015 11:48 am

Harold L. wrote:Btw, you should focus on the relative value, the rising-edge of the current when power off your router(130mA - 70mA = 60mA) instead of the absolute values, because there exists some bias-current caused by things like LCD screen, external ADCs in my measurement.

Surely, those things would not be the reason of this problem since they just have not way to be informed when the router is powering on/off.


there are two reasons for this current:
1. when the AP power off, 8266 will send package for disconnect.
2. 8266 will change data rate to try to connect AP, because 8266 don't know how about AP. May be because the router signal is weak.
High data rate means high current, although a short duration.

Do you have a strong demand on this ? Please tell us your usage occasion.

Harold L.
Posts: 26
Joined: Thu Dec 18, 2014 3:24 pm

Re: Power consumption problem when the AP is not avaliable

Postby Harold L. » Wed Aug 19, 2015 11:25 am

ESP_Alfred wrote:there are two reasons for this current:
1. when the AP power off, 8266 will send package for disconnect.
2. 8266 will change data rate to try to connect AP, because 8266 don't know how about AP. May be because the router signal is weak.
High data rate means high current, although a short duration.

Do you have a strong demand on this ? Please tell us your usage occasion.


Thanks for your reply! Yes, we have very strong demand, because we're designing a hand-held device powered by battery, and customers need to have a longer battery life outside(e.g. on the streets, parks, restaurants...). Our device will upload datas through WIFI only after they coming back to home.

Could we come up with a compromise like introducing some 'gaps' between each Tx retrying? It seems that now the strategy is little bit like a 'flood'. Can we take a strategy like TCP's retransmission algorithm(Exponential Back off) ?

Thanks again, saving power is really matters to us, hope we can find a way together!

ESP_Alfred
Posts: 56
Joined: Mon Nov 10, 2014 7:31 pm

Re: Power consumption problem when the AP is not avaliable

Postby ESP_Alfred » Wed Aug 19, 2015 5:43 pm

Harold L. wrote:Thanks for your reply! Yes, we have very strong demand, because we're designing a hand-held device powered by battery, and customers need to have a longer battery life outside(e.g. on the streets, parks, restaurants...). Our device will upload datas through WIFI only after they coming back to home.

Could we come up with a compromise like introducing some 'gaps' between each Tx retrying? It seems that now the strategy is little bit like a 'flood'. Can we take a strategy like TCP's retransmission algorithm(Exponential Back off) ?

Thanks again, saving power is really matters to us, hope we can find a way together!


1、As you see form table 4, the current rising is inevitable when 8266 send packet.If you want to reduce this part of the current, You could modify the parameters in the "esp_init_data_default.bin" via "flash download tool" to reduce the power of Tx.

2、8266 have some sleep mode, may be you adopt this mode in your occasion.

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