battery lifetime

[realhik]

I am trying to increase battery lifetime for an animal tracker and startet with the T-Impulse Demo application. The device should determine its position approx. every 10 minutes and send it via LoRaWAN. Currently the device battery lasts only a few hours (with display switched off) before it has to be recharged.

Apparently there are many possibilities to save energy but I am not sure if these will be promising.

E.g. GPS has a low power mode but it might be better to disable the GPS chip at all during pause because a cold start after some minutes can be more energy-saving than keeping the chip in a "sleeping" state. There are sleep and deepSleep modes of the MCU but for me it's not clear if the GPS is disabled during sleep modes.

So my questions are:

1. Is GPS active while MCU is in LowPower.sleep() or LowPower.deepSleep() ?
2. Should I disable GPS or send it to sleep?
3. Should I try to initialise the GPS with RTC date/time to do hot positioning?
4. Is GPS UART and interrupt wakeup a problem during deepSleep?
5. Are there are concrete tipps to increase battery lifetime for such an application?

Thx,
Thorsten