I got a couple of Logitech cordless, optical mice for cheap from an eBay auction. They work great, but they are battery hogs. A pair of AA alkalines only lasted a week or two, and when I used rechargeables, they only lasted a couple of days before needing a recharge.

At one point I mused that it would be nice to be able to power the mice with the BL-5C Lithium Ion batteries that power my cell phone. They recharge quickly and hold a lot of current. Only problem is they are 3.7 volt batteries and the mice are designed to run on a couple of AA's in series... 3 volts. I wondered if the extra .7 volt would be a problem. One way to find out. A couple of jumpers later, I had my answer... the mouse seemed quite happy with 3.7 volts.

The hard part was finding a way to stuff the battery inside the mouse. You have to chop a lot of the battery compartment plastic out, remove the springs, and install a connector assembly that will match up with the BL-5C terminals (if you want it to be removable, more on that later).

Step 1: Not a Step, Just a Pic

These two mice are the same model, just different color. The one on the left has been modified to run on a Nokia BL-5C 3.7 volt lithium ion cell phone battery.

I also installed a small slide switch with which I can turn the mouse off to conserve battery power.

Step 2: Clearing the Way

I used a Dremel tool to carefully destroy the battery compartment.

You must take great care not to remove plastic which supports the right and left mouse buttons... nor any that affects operation of the mouse wheel.

Look it over real good before you start chopping!

It might even turn out that the mouse you want to modify cannot accomodate this size and shape of battery and remain functional.

Step 3: The Connector

I butchered a flash card connector out of some other piece of equipment to get this improvised connector which I hot-glued in.

Only two of the finger spring contacts are actually used, the others I bent slightly so they are flatter and don't protrude.

Step 4: Making Contact

The terminals of the battery are somewhat recessed and my spring contacts had a hard time making contact so I built the terminals up with a little solder. My phone didn't care.

This requires hit-and-run soldering. You have to have the iron just the right temperature so you can get the solder on quickly and remove the iron before you melt the battery case.

SAFETY NOTE:  Lithium ion batteries are dangerous critters.  They don't take kindly to abuse. These batteries have a safety device built into them to prevent overcharging or over-current (short circuited) which ends up disabling the battery, but that's better than the alternative which the industry euphamistically calls "venting with flame".  When even the euphamism sounds scarey, you're dealing with some serious doo-doo.  Don't do anything to one of these batteries that can pierce it, overheat it, or otherwise tick it off.

Step 5:

I put some foam rubber in the front end of the battery compartment to keep the battery in snug contact with the connector.

In retrospect, perhaps I could have left that spring in there.

Step 6:

I made this modification about a year ago, before I had a simple way to recharge a Lithium Ion battery ... if it were not removable from the mouse. I have just been using my cell phone to recharge the battery when it needed it, which is about every two weeks or so. (I never remember to turn the mouse off at night with the switch.) I have several of the phone batteries, so I can just slip a charged battery in and put the depleted battery in the phone for charging in just a few seconds.

Step 7:

I just received this gizmo from Hong Kong. It is a nifty intelligent Lithium Ion battery charger designed to charge cell phone batteries by slipping them under the spring-loaded clear plastic part, bringing the battery contacts against the two adjustable arms.

It is a simple matter to clip on a couple of jumper cables to charge a battery, even if it were still in a mouse.

Making and mounting the battery contact assembly in the mouse was probably the hardest part of the project and required a lot of fiddling and adjustment. The whole mess could be avoided by hard wiring the battery and just using one of these chargers, but you couldn't use the mouse while you wait for it to charge.

This charger cost me $1.50 US with free shipping! from an eBay auction and it works like a champ.

I've been powering this mouse with BL-5C's for over a year now and the over-voltage has produced no adverse effects, so I decided to share it with the world.




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    47 Discussions


    2 years ago

    I would like to do this to my Turtle Beach x41 headset. Would the process be basically the same? This headset eats batteries like crazy.

    Hi Dave,
    your posting inspired me to do exactly what you did on a wireless keyboard.
    Except I left the battery on the cellphone. May be in the long term I will try to move the battery into the keyboard and make DIY battery compartment. Sounds very challenging though. May I'll just hot glue the whole cell phone on the keyboard. :)

    So, on a battery such as that, only two of the contacts are actually used to power something? I have a few HTC G2 batteries laying around that I wanted to repurpose. I see where they note negative and positive. I just have to make contact with these for it to work?

    1 reply

    Usually, the extra pins are for battery temperature monitoring.

    As long as you are using a charger that plays nice with only the + and - pins then
    YES, you only really need the two pins.

    I will do this with conductive wire glue

    That mouse must be huge... I'm currently doing this with a logitech mx600 laser mouse, and I'm having a hard time figuring out where I can mouth the USB piece I have to take the power from the battery. I completely removed the battery compartment haha.

    Hs anyone tried using a cellphone battery on a digital camera? This is my battery hog. 2 new double a battries will last for onlt about 10-12 pics and then they are to weak. I definetly have to use rechargables fot this dood. They last just as long and saves lots of money. 2005 model HP. It will also run them down lust being in the camera.

    I hyave a 2005 Logiech cordless mouse that uses 2 AAAbatteries. I use rechargables and they last at least a month on a charge with my wife playing pc games 4-5 hours a day. Model #M/N:m. RN67 Just have to clean lent out of it monthley or it gets crankey. You have a good instructable.

    Great Mod!!! I want to put a lithium polymer battery in a controller I have, but I do not know if it can handle the voltage difference. It uses two AA batteries and I want to put a 3.7 lipo battery. Is there any way to test if my device will be ok with it or will I just need to wire it and hope for the best? Thanks.

    Do you think maybe this would also work with this keyboard?
    The keyboard can take up to 4x AA batteries. I don't think its completely necessary to have 4 batteries to power it tho, provided the batteries in it have enough juice. But if you think just one 3.7v wouldn't be enough, how about 2? 7.4v seems like a much greater amount then 6v though, has a universal charger that can be used on any flat phone battery with end connectors, it is under $10

    3 replies

    Would you be able to find a link to this device, please? I'm having trouble finding it.

    Here is the eBay auction where I purchased mine:

    It is still active as of today.

    He has revised the auction and raised the price to $2.50. I don't blame him. LOL

    Crazy idea... but so that you don't have to worry about charging it when its dead and not being able to use the mouse... Why not use one of those charging mats as a mouse pad when it dies? I mean only use it while its dead otherwise your effectively making it a corded mouse.

    Then again having no personal experience with those charging mats I don't know if this is a benifical idea.

    I have the exact same mouse at home a pair of rechargeable batteries last up to six months on mine, so i find weird if your batteries only last a couple of days , maybe they are deffective , i don't know.

    2 replies

    My mouse only uses one AA I use rechargeable Duracell's for it and a few other things I am actually charging my battery before it goes right dead.
    I use the control panels mouse battery meter as a guide and only once have found my self swearing at it because it ran out of power. lol I won't be trying it on this mouse but I was given an idea about remote maybe I will try to customize a remote to use a dead cell phone battery since the battery are excellent just the phone is dead.Great Idea anyhow later

    great mod. i keep this idea as mandatory at my house. nothing uses disposable batteries anymore. we take batteries from cellphones that won't hold a full charge anymore and mount them in universal remotes. i have gotten 3 years off one charge from a "dead" battery.

    take it a step further and try upping your current capabilities in your ups. i managed to double mine. led flashlights using laptop cells. glad someone is writing this stuff up