Hello MorganS,
thanks a lot for your post. Based on your info I would go the way with regular relay or some of the high-side switching chip. I already search for some suitable relay but as the Arduino pin can only give max of 25mA per pin I need to find some suitable one to be able to switch the load at this small current (ideally running on 1,8 V :o) which I thing is not possible at all). I saw some board with optocoupler to be able to give more current for the relay to be switched on. But I am not sure if there is some small power consumption of such things when the load is off. As the aim is to have the device running for a long time only on batteries. Next thing is that I am running the arduino (or better ATMEG328P-PU chip) at the smallest configuration possible and with 4 MHz external oscilator on 2AA batteries. It communicate via NRF24L01+ device then. Currently I am able to run such device without problems but now I need to add this power switch for the servo which will have its own power supply again from batteries. I see that the BTS and BTT chips which you recomend run on 5V if I am correct right?