re: Dumb question about police and their parked cars

Don't they have supplemental batteries and UPSs and so forth for things like that? Are they really running a whole computer system off the single Diehard battery under the hood? The same battery that runs the vehicle? If that's the case then you can't convince me there isn't a better solution than leaving the vehicle running almost all day and night and doing all the engine damage that's being done and wasting of fuel.