Asset Tracker V2 power consumption with Thingy:91

RE: Asset Tracker V2 power consumption with Thingy:91

Øyvind — Mon, 01 Nov 2021 11:07:34 GMT

Ilkka, very happy to hear about that result!

In the DNA network, did you try to change the default PSM parameters? Do you know if PSM is possible, and if so, what settings should possible?

-Øyvind

RE: Asset Tracker V2 power consumption with Thingy:91

Hidastelija — Wed, 27 Oct 2021 12:14:59 GMT

We did some more testing and got some info. Apparently DNA network didn't like the default PSM parameters in Asset_tracker_v2 example. The default parameters are too long sleep time and too short active time. As a result the network didn't accept PSM.

However, when using Telia sim card, current consumption was as low as 400uA avg with 8min data update interval. This is great!

Configuration:
- Thingy:91 (1.4.0 & MFW 1.3.0)
- Asset_tracker_v2 (low_power_conf + GPS disabled)

Using LTE Link Monitor I was able to test different network parameters with AT+CPSMS to find a configuration that works for DNA network.

Ilkka

RE: Asset Tracker V2 power consumption with Thingy:91

Øyvind — Fri, 01 Oct 2021 10:43:43 GMT

Hello Ilkka,

I've talked to our Thingy:91 designers, and they say that with v1.6 of the Thingy:91 you should be able to achieve up to 6 months of theoretical battery life. With the Asset Tracker v2 low power config it draws just under 40 µA at 3.7V in PSM, and removing the accelerometer part gets it down to 10-15µA in PSM.

Thingy:91 versions prior to v1.6 are not able to achieve lower than 200µA due to the RF switches. On v1.6 these are turned on only when needed, controlled by one of the COEX pins in the modem.

The battery life is, as mentioned, affected by GPS fix time, and bad reception depending on how much the device needs to search for the network..

Kind regards,
Øyvind

RE: Asset Tracker V2 power consumption with Thingy:91

Hidastelija — Wed, 29 Sep 2021 15:17:54 GMT

Hi Övind and thank you for the reply,

The thread on Thingy:91 Power consumption is interesting, but it is kind of at the other end than I am at the moment. Right now I'm not trying to get the absolutely lowest possible power consumption. I'd be happy with around 0,4mA avg current (about 4 months battery life) with SW that is as close as possible to the Asset Tracker V2 example.

The asset tracker V2 example is very nice and implements most of the requirements for the prototype that I need to create. One of the major and to me most difficult tasks is to get the power consumption low enough for the Thingy battery to last some months.

According to the modem specs, the difference in avg current between PSM and eDRX is 30uA or less. The actual figure naturally depends on the timer for each mode. To get the modem to reasonably low power mode, I changed the code in Asset Tracker V2 example to request eDRX instead of PSM.

I think the Asset Tracker V2 only tries to get PSM, not eDRX at all. I did this change, because lte_evt_handler / "case LTE_LC_EVT_PSM_UPDATE" in modem_module.c prints -1 for TAU. After changing to eDRX the debug print in "case LTE_LC_EVT_EDRX_UPDATE" looks ok to me. I just got a new SIM card to TELIA network. I will test this next with the original PSM config.

Can you tell me: Given favorable network conditions/parameters, can Thingy:91 with the Asset Tracker V2 SW be expected to run months on battery when built with low_power_conf?

Kind Regards,

Ilkka

RE: Asset Tracker V2 power consumption with Thingy:91

Øyvind — Wed, 29 Sep 2021 13:33:07 GMT

Hello,

[quote user=""]Is the nRF52 part on the Thingy:91 using any power? I have not updated/changed the SW on the nRF52.[/quote]

The Thingy:91 USB connector is connected to the USB interface of the nRF52840 SoC. This enables PC communication and battery charging.

[quote user=""]What are the most power hungry parts in the application --> where to start optimizing?[/quote]

Have a look at this forum thread on Thingy:91 Power consumption, there is also this forum thread on Current Measurement on the Thingy:91. And the blogpost on Getting started with current measurements on the nRF9160DK

[quote user=""]How long one should expect the Thingy can run on battery using default Asset Tracker V2 parameters?[/quote]

This is difficult to tell as this depends on the network coverage, PSM/eDRX and other factors on the network. Have a look at the nRF9160 PS chapter on Current Consumption

[quote user=""]The modem is configured to use eDRX, because in my earlier test the Thingy logs with default SW requesting PSM got a response -1 from network (DNA / Finland). I assumed the response says no PSM.[/quote]

Please note that you should choose either eDRX or PSM, these can not be used at the same time. Have a look at the Modem Sleep Notifications guidelines.

Kind regards,
Øyvind