Introduction: Upgrade Your Dead Cordless Phone

About: Professional work in various electrical and mechanical fields, obscure sense of humour and typically willing to help... Currently under contract designing environmental monitoring equipment.

So my cordless phone died and at the end of troubleshooting I found that it was the battery that was no longer working.

Several phone calls (I used the old phone) later I found that the cheapest battery pack was $19 plus tax.

Some observations of the original pack revealed that the pack was the size and voltage of 3 Ni-MH AAA batteries.

I could buy 3 of these locally for less than $1.75 each.

NOTE do not use regular AAA batteries for this as you will produce battery waste and possibly electrically destroy your phone from the higher voltage that a regular battery has or start a fire if you forget and plug it into the recharger...

This procedure should work with most cordless phoned that have a molded battery compartment.

Step 1: Remove and Disassemble

First you will need to remove the old pack and disassemble it for the parts..

You will need to cut the shrink wrap off and harvest the wires.

The wires will need to be either cut off or de-soldered.

I chose the later route and desoldered the wires from the pack, possibly from remembering all the movies telling you not to cut the red wire...

Step 2: Assemble the Battery Carrier.

In a previous instructable I found several inexpensive LED flashlights at a local liquidation supermarket. These flashlights were powered by 3 AAA batteries and I chose to use the battery carrier parts from one of these. The metal parts of the carrier showed to be the exact parts that were needed to complet this project.

These metal parts can be found in a large number of battery holders including old remote controls and toys. Just be sure to get the right size, You will nee AAA battery size.

NOTE: I have recently found out that Home Depot carries a Husky branded 3 AAA LED flashlight that costs around $7. This is the exact model that I bought from the liquidation mart for $3.

You will need to disassemble one of these carriers of you can use parts from any electronic gadget that uses AAA batteries. In this case, the metal is held onto the carrier by melted small bits of plastic. This can be cut witha sharp knife to remove the plastic. The metal parts will slide right off of the plastic holder. Specifically you will need the springs and metal bits.

Two of these metal bits are soldered to the negative (Black wire) and positive (Red wire) leads of the electrical connector.

The spring is negative and the plate is positive.

Step 3: Hot Glue Heaven

Using hot glue you will need to create a series electrical connection between the batteries. Remember that the spring is negative and the plate is positive. You are creating a single battery that is 3.6V out of 3 individual batteries that are 1.2V each. You will need to connect the positive to the the negative terminals.

The plates from the flashlight battery carrier are hot glued directly to the chassis of the phone to accomplish this.

Remember that when the batteries are installed there should be only one continuous series connection. Any touching of the plates by the adjacent battery will create a short which can result in a fire.

Step 4: Populate Your Phone

Now you can install the batteries. The spring will be for the flat end of the battery and the plate is for the knob end. If you followed teh directiond the phone should light up and work. Black is negative and red is positive for reference.

If the batteries get hot then you have short and you should immediate remove the batteries and separate the connection plates.

Finally you should attach a piece of foam to the battery door to prevent the batteries from moving about. I used a small piece of weatherstrip foam with an adhesive side.

If you used the same type of batteries as were removed then you should be able to charge the phone as before. The type of batteries needed will be embossed on the battery pack. This particular phone used Ni-MH.

In the future if your batteries pack it in you will be able to replace them effortlessly...

NOTE: The old pack was taken to Home Depot and placed in the battery recycle bin.

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