No red light on key fob also works strangely

I was wondering if anyone can shed some light on why this is occurring?

Recently bought 2013 Prius V got 2 keys. Both red light does not turn on when you lock or unlock car? I have a Prius C with identical key and red light turns on. Why no red light?

Also one of the keys does not work but if I go close to the car and open with key in hand and pull door or swipe the sensor on door handle, the key will start working and does so probably for 15 minutes then wont work after unless I repeat procedure.

Could it be a case of just replacing battery? I did measure with multimeter problem key 3v battery was getting around 2.6v.

Both keys inside car starts the car fine. Although one time I did notice the key light on dash but I moved the key from the 12v/ usb port area to the cup holder area the key light went away.

 

That may have been the issue, both key batteries replaced and working OK so far.

 

Now my 2012 Prius C is having similar issue in aspect of 'key not detected' but the key is in the car and the key fob battery seems good. It seems to happen if I'm stopped or parked and someone opens the door to get in or out, I will have to move the key around to eventually get the warning light and buzzer to go away. I will try change the fob battery but I thought it was independent of this.

I just searched another thread on this issue and guy said it was interference from Qi charger on the vent left of steering wheel which is same setup in both my cars it will be something to look at.