Simple 5v Battery Backup Circuit

Introduction: Simple 5v Battery Backup Circuit

About: m mad about electronics, technology........who m i ??? son just don ask that .......

It’s a simple 5v battery backup circuit with constant slow charging facility. Its mostly suitable for microcontroller projects where we need constant current source without any cut-out. Whenever mains fails the battery takes the load without any delay again when mains restores batter goes to charging mode again. Its not just a idea or diagram I developed this circuit for my own (my digital clock need’s constant 5v power supply) and still using this, till now without any problem. Make the circuit and if you face any difficulties just give me a call



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    14 Discussions

    Looks like you need 6v battery to accommodate the 1V drop across the 1N4007 diode.

    what is the use of 680 ohm and IN4007 doide in series with the voltage regulator?

    What type and size cells are you using with this circuit?

    3 replies

    You can use almost any kind of battery under the voltage rating. It may AA battery x 3 = 4.5 or lead acid 5v battery. almost any kind

    How do you get 5 volts out of a lead acid battery?

    They are 2.2 volts PER CELL!

    Also to get 5 Volts out you need to ADD 0,7 VOLTS to the 5 VOLT battery for the drop over the diode!

    So that would call for a 5.7 VOLT battery, NO SUCH THING!

    Don know about you sir but my design and "also" my circuits just works
    fine with me and also still working ,if you can make it better than plz
    do your best.And One more thing i like to remind you these designs are ONLY
    basic idea Circuits (DIY) ""NOT FOR COMMERCIAL USE"". So in that case
    little much miscalculation is acceptable. Have a Good Day

    Thank you for your circuit. What must I change so that the battery is not charged at all when mains is restored?


    3 years ago

    Did you use the resistor 680 kohms or 680ohms and what if use 6v battery instead of 5 v wht u used in your diagram..should i change any components or it will work in this diagram and whats the purpose of the led? ? Is it for showing the battery is on while ac power fails?? And when ac power is on and this led will stop?? And also is there any chances to get the battery over charging or it will break the charging when it will be full charged and separetly my load can get from the constant power from ac until it it gone by loadsheding?? Plzzz reply...thanks for your tutorial it helps me much....

    1 reply

    It says 680r "r" thats mean "680 ohms" NOT K its R.......if want to use 6v than u have to change all the setup. its designed for 5v NOT 6V. the LED its just a indicator nothing else. and its a simple nd easy circuit just a basic battery backup circuit it will NOT control the battery charge or OVER charge.


    Couple of more questions, what is the maximum current the circuit can provide.

    Also, can the circuit be upgraded to check when battery is fully charged, so that it does not damage it.

    I am looking to use it to power my Raspberry Pi.


    Actually its NOT ment for that kind of job its a Battery-Backup Circuit
    its Not a charging circuit. you can search the Net you will surely get
    something for I-phone @ turbiny