You can use this simple Mobile charger using 6 volt Emergency lamp battery. Take an out from the Emergency lamp battery using a Mono jack socket and plug in this charger into it using a Jack. On the other end, connect it to the mobile phone using a suitable jack. Full safe, no damage due to power line spikes, lightning etc. It also drains the emergency lamp battery which is good for its life because it is sleeping most days without use. You can also use the same circuit for 12 volt car battery .
1. Regulator IC 7805 Provides 5 volt for charging. Mobile battery is rated 3.6 volts but is requires 5-6 volts for charging.
2. Resistor R1 limits the charging current to a safer limit.
3. LED indicates the connection to mobile battery and charging status.
4. Diode D1 protects polarity