Opening Up and Modding a Li-ion Battery and Connecting Into a Gadget to Recharge As Needed


Introduction: Opening Up and Modding a Li-ion Battery and Connecting Into a Gadget to Recharge As Needed

About: Video game console modder.

Why is this useful? When you're making an electronics project, like a portable handheld video game console system, it isn't easy to house a large battery pack inside the enclosure; however if the battery is able to be split into two parts, it means it is far easier to locate the batteries into your project. My hobby is making handheld portable video game consoles from consoles not designed to be used as such; so using good quality batteries are important to my work, and locating them in a case so they fit ok is important.

The batteries I am using here are Canon BP-915 or Canon BP-911 camcorder batteries as I use them in my projects for making handheld portable video game console systems. The principles and methods are however similar for other makes, brands and sizes of cells.

Li-ion batteries, like ones from camcorders, are made up in multiples of 3.7v cells, so for a 7.2v or 7.4v battery pack, you actually have two cells inside, for 11.2v you get three cells inside.

As long as you are careful, it is quite easy to segregate the cells and rewire the batteries, keeping the battery protection circuit in place, to stop over and under charging. Also in this guide, I cover how to connect the battery terminals to a charging jack.

Here's how... 

Step 1: Release Tabs

There are two metal tabs on the sides of the battery, one is for the positive battery terminal and one for the negative battery terminal. Get a pair of pliers to snap off the plastic surrounding the tabs, and then with a small screwdriver, pry the metal tabs free. 

Step 2: Pry the Casing Off!

 Insert a fairly large screwdriver with a narrow edge into the groove between the two case halves to pry them apart. Don't force the screwdriver inside or you may damage the cells if being too harsh. Also, don't use the screwdriver anywhere near where the voltage tabs are, as between them is a small circuit board you must not damage (the battery protection circuit).

If the case refuses to come off without a fight, use pliers to hold the metal tabs and lift up the plastic casing, to separate the two case halves. Holding the metal tab in place takes the pressure off the circuit board.

Step 3: The Protection Circuit and Wiring the Battery Pack

The protection circuit (the green board in the picture) is vital - it stops the batteries from draining too much (which would cause the batteries to swell, and get damaged, maybe explode if subsequently recharged), or over charging (batteries would literally explode like a small granade). It is therefore important not to damage the circuits.

They come designed to work for a given amount of cells and also voltages, so don't replace them with other similar circuits as if they are wrong, you could have an explosion ready to happen. This is a great advantage in using Li-ion cells, they have the protection circuit built in.

Also, it is important to use a battery charger designed for the brand and type of batteries you are using.

Regards wiring the batteries - simply extend the wires and contacts in the battery with wires, designed for 3 amps is fine, to the same terminations as were on the battery originally. That will then allow you to separate the cells from each other, and making them easier to mount into your project. 

You can't just solder a connection to a battery terminal, solder doesn't stick. Dab on some flux first, then solder from a hot soldering iron, and you should end up with a strong solder blob on the battery you can solder onto. Don't be long with the soldering iron, it isn't good to keep a hot soldering iron against a battery for more than a couple of seconds at a time.

Step 4: Result

This is an example of where it is useful to separate batteries. 

The colour of the cells are not important, I have seen orange and red ones, I am sure there are others about too!

Step 5: Add Charging Jacks

If the batteries are dismantled, you can't plug them into the charger anymore, so it makes sense to add a female port charger to your gadget, and a male one to the charger unit. The charging jacks are taken from a PSone console / screen, although of course you can use a male and female port from whatever suitable you have.

In regards to the PSone charging jacks, the middle connection is positive, the two outer are negative.

It doesn't matter what colour wires you use, but ensure positive goes to positive and negative to negative.

On the female port (yellow in picture), wire the "+" to the positive battery terminal, and "-" to negative. Wire the male port (green in picture) the same way, and to the battery charger unit.

In this way, you can recharge the batteries as you need to.

Step 6: PDF and Video for Project

Here is a PDF file from my Wordpress site on this subject, along with a video too, showing the steps in more detail.

Please visit my Wordpress site for details of more projects!



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    11 Discussions

    hello!! you can give me the diagram to conect this bateries in a sega dreamcast? i want to make a dreamcast portable

    Hey, could you please point me in the right direction for gamecube batteries?

    I know it has been like 2 years but do you still have some of those psone screens?

    Also, the tact switches online are onlt solid round tops, unlike the ones in the video. are those okay to use and if so what dimentions? Sorry for asking so many questions, but it seems like i'm running into problem after problem.

    1 reply

    There are various types of tact switches, all fine. Fancy joining and posting your queries in my forum, we can help you out more then?

    Thanks! This has nothing to do with batteries, but I can't find a reasonably priced PS1 LCD screen. Where do you get yours from, or is there a knock off brand that would cost less, but still get the job done?

    1 reply

    Best screen is the Sony PSone screen, for the size. They cost about £30 on ebay, which is a fair price. I have some spare, similar price. (UK).

    Great guide! I have two questions though, (my first portable system). Do I HAVE to separate the batteries or can I just remove the casing and leave the board attatched to the batteries? Also, how many li-ion battery packs do I have to use for a portable gamecube or N64? Does it depend on the screen I use?

    1 reply

    You can keep the batteries in their shells if you have space, if you open the batteries up they can be separated if you like - optional. Battery separation is useful if your system can't fit a battery pack in its original size. Ideally two or three packs for N64 (eg the Canon BP-915 batteries), the GameCube needs 11.1v - 12v for the regulator board to work as getting 3 amps out of 1.9v by other means isn't easy. The Canon BP-915 cells aren't ideal for the GameCube therefore.


    BTW, if you want a free guide for the PSone, etc, please have a look on my Wordpress website: