# How to convert 6V 4Ah Battery supply to usable current of range "mA"?

Discussion in 'General Electronics Chat' started by vivekanantha7, Dec 1, 2008.

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1. ### vivekanantha7 Thread Starter Member

Dec 1, 2008
27
0
Hi friends,
I wish to know how to convert a 6V 4Ah battery supply to usable current of range "mA". I have looked into lot of forums and found that using of LM7805 will have good result but the output current will be around 1A. But i wish to have the current in the range of 500mA for using this a backup battery for Microcontroller projects which requiers 5V and mA of current. Also i feel that the battery provide a long time supply in mobile time ie, while using circuit outside without any domestic current supply. Please help me out in this situation.

2. ### mik3 Senior Member

Feb 4, 2008
4,846
63
Just to clear things up, a device draws the current it needs if you apply the correct voltage across its terminals. You don't need to provide the correct amount of current but the correct amount of voltage.
In your case you need a 5V voltage regulator to regulate the battery's voltage and keep it constant to 5V. An LM7805 is a 5V voltage regulator but you cant use it with a 6V battery because it needs at least 7V input voltage to work properly (it has a drop-out voltage of 2V). You need to use a low drop-out voltage regulator.

3. ### vivekanantha7 Thread Starter Member

Dec 1, 2008
27
0
Thank you sir. I agree with you. In that case shall i use 12V 4Ah battery instead on 6V battery..?

4. ### Bernard AAC Fanatic!

Aug 7, 2008
4,244
423
A simple solution is to add a diode or two between 6V battery and your load, anode to + battery,-[band] to load. 1N4002 or equivlent will do. I used this when working with TTL chips.