Not to worry about a gy401 used with a stock Axe 3 in 1.

The GY401's operating voltage spec. is: +4.0 - +6.0 vdc.

My Axe's 3 in 1 BEC output is 4.95 vdc.

Note- my Axe was shipped with the LiPo.. I doubt the NiMh version would be any different since the Rx is the same regardless of batt. type.

RWW