Battery saver, what does it do?

The battery saver function has been around in Motorola two-way radios for a very long time. As the name suggests, it helps to reduce the current consumption of the radio during receive thereby improving discharge time (i.e. battery takes longer to get flat).

In order to reduce current consumption during receive, the microprocessor will turn the receiver backend on and off when there is no traffic on the channel. The net result is that the current drain from this circuit is reduced by anywhere between 50 and 90% depending on how busy the channel is.

The downside of this feature is, since the receiver gets turned off every few milliseconds, there is a chance that the radio will miss the first part of a call. To overcome this, the receiver can also be woken up by listening for the preamble bits that normally get appended to the start of a transmission. This is enabled in MOTOTRBO radios by ticking Preamble.

If you want to disable battery save altogether, you can do so by un-ticking Receive. This will switch off the receive battery save feature I've described above but will increase current drain. This maybe useful in Control Station radios which are connected to an external power source (i.e. battery drain is not a problem).