Thank you. I tried setting SW3 jumper to BATT and it helped alot, it didn't solve all power issues but now Nybble doesn't spasm at all and can make several postures before running out of power: I unput the next command, I hear servos working, but the cat can't move. Also there is a faint smell from around battery's minus contact where the pressure release valve is probably located. Definetely a battery problem, waiting for unprotected ones. With SW3 jumper in V+ position I get 6.3V on the board's servo contacts, in position BATT 7.55V. As a side note, I saw the recomendation in 4.1.4 before, but misunderstood it. TowerPro specifies operating voltage 4.8V~ 6.6V and 5.0~6.6V for Nybble's servo motors. I thought that BATT setting was for custom projects with more powerfull servos, and decided not to use it.

"Robiton 900mAh protected 14500 3.7V li-ion ICR" don't work with Nibble as already stated above by Pavel Yakovlev. I was not even able to calibrate the servos with those batteries. When Nybble starts up several servos are moving at the same time and trigger battery protection, the voltage on one of two batteries becomes close to zero. This battery has maximum discharge current of 1000mA, it seems it's not enough for Nybble. https://www.robiton.ru/sites/default/files/P00097835N11321.pdf "Robiton 3000mAh protected 18650 3.7V li-ion ICR" don't work - I had those batteries at hand and tried them after the first pair failed me. With these i don't get low voltage problems, Nybble can get into starting position without problems most of the time, but any command from the remote makes him spasm (all servos move in seemingly random way). This battery has maximum continious discharge current of 3500mA, probably not enough for Nybble. https://www.robiton.ru/sites/default/files/P00137463N13489.pdf Now i'm waiting for the "Rexant Li-ion 14500 unprotected 750mAh 3.7V" batteries and hope they solve the problem. I wasn't able to find Nybble's servos electical specs other than voltage to calculate consumption: https://www.towerpro.com.tw/product/mg90d-2/ https://www.towerpro.com.tw/product/mg92b/ Does anybody know how much power Nybble actualy needs?