Havis' ChargeGuard is an easy-to-install auto shut-off timer designed to safeguard expensive communications devices and computers with intelligent circuitry protection. ChargeGuard works by automatically turning mobile equipment on when you start the engine. When you turn the engine off, the equipment stays on for an adjustable period of time, then is automatically disabled. When properly deployed, you can ensure that you'll never have another dead battery, at a very affordable price -- cheaper than a single tow.