12V to AAA Mp3 Player

I'm completely new to electronics. Hope that someone with good knowledge will help and guide me through the solution, step-by-step.

I have a common cheap mp3 player which can be connected to a USB port for battery charging and transfering of files. The mp3 player uses an AAA battery with 1.2V and 850mAh.

I need to connect this mp3 player to a Lead Acid 12V battery.
The current (mA) that the mp3 player consumes is unknown.

How do I do this? What do I need?
I would like to solve this problem in a cheap and easy way.

Thanks

You can use an Ipod/Iphone usb car charger. They are very cheap. Here is one from EBay:

**broken link removed**

Sounds like a ~90% waste of power to me. Why do you need to change AAA batteries are cheap?

Re:

@AlainB
Thanks for sharing your idea. Good to be considered very efficient and simple.

@birdman
I would like to eliminate the use of AAA batteries becasue since that I will be using this mp3 for long hrs, the battery duration won't last that much. And don't want to carry batteries with me! I only want 1 battery that connects everything (speaker, amplifier and mp3).

I would like to examine more ideas of what can I do...!?

birdman0_o said:

AAA batteries are cheap?

Click to expand...

That's not the case everywhere birdman0_o.

Arpa, what kind of tools do you have? Do you know how to solder?

In that case, you can use a LM317 voltage regulator

LM317 - Wikipedia, the free encyclopedia

This is how to use it
**broken link removed**

Why would you want to carry a heavy lead acid battery around with you, I'm sure 4 triple a batteries are cheaper than a big lead acid one.