From PSPWiki

A Suitable JigKick Battery. It is a Sony "standard" Li-ion 1800 mAh

This is a battery with its serial changed to 0xFFFFFFFF. When a psp's battery serial number is changed to 0xFFFFFFFF the PSP boots the ipl from sector 16 on the physical drive (the Magic Memory Stick). This file can be installed by several programs like using msinst in team c + d's Pandora Battery Package. This unlocks the service mode of the PSP and launches the IPL from the Memory Stick (instead of from flash0). Sony have done lots to prevent this and the new PSP Slim motherboard (TA085v2)can not write to the battery EEPROM at all because Sony disabled it, therefore you must use the hardware mod. Also any new battery which is official (Including Phat and Slim) and all fake batteries cannot be converted in a Pandora's Battery. So the advice is to buy a new one and use the original one as a Pandora's Battery. This is ideal becuase a Pandora's battery can do lots of useful things like run the Time Machine and along with a Magic Memory Stick you can Unbrick/Downgrade any PSP. Or you can just use the orginal one and convert it back to a normal battery, if you don't want to spend any money. You can also buy a Datel Tool Battery. This is the same as a "Original" JigKick Battery. But, even if you have a Datel Tool, you still have to make a Magic Memory Stick.

Softmod

For this you will need a spare compatible battery. And a homebrew PSP 1.50 or a CFW PSP eg. 3.80 M33 with 1.50 Kernel addon. You wil first need a pandorable battery. You can check if yours is by this list.

There is now a method that will enable users of custom firmware above 3.71 M33 which does not automatically have the 1.50 firmware kernel to create a Pandora battery, by interfacing directly with the PSP's SYSCON chip. (Or for those who are on Slims) This method uses code by SilverSpring, and can be found here.

Requirements

• A Pandorable battery (spare if possible), check if it is pandorable in the list below
• Homebrew Capable PSP. Version 1.50 / or any CFW with the 1.50 Kernel Addon (Only for Fat PSPs) or 3.xx+ Kernel CFW on a PSP (For both Fat and Slim PSPs)
• Pandorafiying Software; Download:

OS Pandora Battery Tool for 3.xx V6 From Cory1492

Pandora's Battery Creator for 1.50 From N00bz

Software:

• The original Pandora's battery creator only for suitable fat batteries only. However, other alternatives such as the UPMS Installer, Hellcat's Pandora Installer for 3xx kernels, can convert a Slim battery to Service Mode successfully. Download pandora files; battery files included in it, only works on 1.50 or CFW with 1.50 kernel.
• Cory149's tool which can even convert some old slim batteries and fat suitable batteries.

Is Your Battery Pandorable, or not?

Working:

• Sony Slim "standard" Li-ion 1200 mAh
• Sony "standard" Li-ion 1800 mAh
• Sony PSP-280 2200mAh
• Datel, PSP Battery 3600 mAh (X2)
• Datel, PSP Battery 1800 Max Power
• Datel, PSP Battery GO MAX (Model # GM1000, uses AAA batteries) note: If u remove the batteries, it resets the serial back to all 0's

Not working:

• 3.6v 3600 mAh Battery Pack (Silver letters) (Model PSP-360) (Fake)
• 2600 mAh Mega Battery Pack (Fake)
• Atomic Battery Pack 3.6V 1800mAh
• Sony PSP-280 2200mAh (Fake)
• Sony PSP Bloc-Battery pack 3.6v 1800 mAh
• Battery 3600mAh, unknown brand, (china made model NK-RH008) (Fake)
• Battery Pack, unknown brand, (lithium) 3.6v 3600 mAH (Fake)
• Intec 1800 mAh Li-ion
• Intec 2200 mAh
• UltraLast e-Boost 3.7v 2200mAh Li-PO battery

Taken from Max Console

Installation

• First make sure you have the requirements, then download the software depending on what firmware you are on.
• If you are on 1.50/CFW with 1.50 kernel download the pandora files; which can convert only phat batteries, since it only works on Phat PSPs. However, the alternative options for Slims are available.
• If on CFW with no 1.50 kernel download Cory149's tool, which can convert all batteries, and works on both phat and slim PSP's, only on CFW.
• Whichever one downloaded put it in the GAME folder, but you will have to change your kernel depending on what you downloaded.
• If you downloaded the Cory149 tool, make sure it is set to 3xx kernel.
• If you downloaded the Pandora tools then make sure it is set to 1.50 kernel.
• Run it on the XMB with the battery and Press triangle if you plan to make use it for normal use again.
• Then go back on the program and press X to convert to Pandora's Battery.
• If successful, take it out and plug it back in with no MS, (or an MS that has an ipl that cannot boot with a Pandora Battery) the screen will stay blank.

Hardmod

For this, you will need to open up your battery, and maybe need some soldering skills, and guts. The best thing to use is a Datel tool battery if you aren't sure about what to do.

Datel Tool Battery

You can find a TUT about making a JigKick battery by the hardmod method here.