Tire Patrol batteries can last 1.5 years if the sensors are threaded on and never taken off. However, if you take the sensors off anytime you're going to be somewhere for a week or longer then the batteries can last over 3 years.
When the batteries need to be replaced, you simply e-mail a copy of your original receipt for your original sensors to contact@rvibrake.com and once we receive the e-mail we ship you new sensors for $15/sensor.
After you complete the purchase of the replacements, email the receipt to contact@rvibrake.com.