A battery on float charge should be ok as the power source; but good filtering of the supply to the 4060 will still be necessary to reduce voltage spikes. Consider using a transient voltage suppressor plus capacitors across the supply, and chokes in line with the supply rails. Build the timer circuit on a pcb; not a breadboard. Use compact wiring and screened connections to the pcb. House the circuit in a screened enclosure.
A battery on float charge should be ok as the power source; but good filtering of the supply to the 4060 will still be necessary to reduce voltage spikes. Consider using a transient voltage suppressor plus capacitors across the supply, and chokes in line with the supply rails. Build the timer circuit on a pcb; not a breadboard. Use compact wiring and screened connections to the pcb. House the circuit in a screened enclosure.
If all you are running is CMOS logic you can use something like this:
A 12 volt zener diode will keep the voltage from going above 12 volts.
If you have higher current loads like relays and "stuff" they still need to go directly to the battery.