Do not keep batteries in the cm15 unless you plan on moving it from room to room. It does not like to be powered by batteries when it's plugged into ac power.
A diode in the batteries path turns off the battery's circuit when the
CM15A is plugged in. So when the
CM15A is plugged in, there is no electrical difference with or without batteries.
That being said, when the batteries are good, they will always hold an input to the micro-controller at ground. If they are weak or not there, this input will be pulled up to +5Volts. If you are having problems when the battery is present, then you could have a bad micro-controller.
Now, if I were to unplug my AHP unit from the wall, remove the batteries and wait a few seconds, then plug it back in, then the RF remote will turn units on and off without problem. Seems the AHP is generating a code that interferes with proper operation.
One PossibilityBecause of the design of the
CM15A's RF receiver, a high level of ambient noise in the correct frequency range can flood the receiver and cause it to have difficulty recognizing the correct signals (
from remotes, etc.). When you unplug & remove the batteries, you are resetting the
CM15A's accumulated ambient RF noise level to zero and that allows the the remotes to be recognized clearly & immediately.
Everytime the
CM15A receives an RF signal from a remote or motion sensor, it increases it's ambient noise level. During quiet times (
no signals) this accumulated ambient level starts to lower. If there is a lot of heavy X10 RF signal traffic or some external signal beyond your control, this ambient noise level will not lower and could increase to the point of saturation... where it can no long see the stronger wanted signal (
the X10 signal).
Trying different locations of the
CM15A and/or
the orientation of it's antenna may help to reduce the level of unwanted RF noise that it picks up.
[Side Note: This is why, when modifying the
CM15A's antenna, the correct length is important. The correct length will prevent a lot of external uncontrollable RF noise from entering the
CM15A's receiver. And of course, it's maximum efficency will be at the X10 signal's frequency.
]