DIY Triple AAA to 16340 Adapter




Introduction: DIY Triple AAA to 16340 Adapter

Hello to everyone.

In this instructable i am converting a triple AAA flashlight battery power supply in one 16340 power cell.

If you ask me why, is because recharging AAA batteries takes my battery charger more than 8 hours to charge AAA batteries and their capacity (700-800mAh) is not worth the time, while 16340 is cheaper, decent in capacity, i can recharge it in one third or less of the time and of course is one and not three pieces if you want to carry a spare.

As for the voltage, three AAA alkaline batteries in series give 4.5V when they are fresh, three rechargeable AAA NiMH (or NiCd) give 3.6V and the 16340 starts at 4V so there isn't any voltage problem for the flashlight.

The triple AAA battery supply measures 20mm in diameter and 53mm in length. The Li-ion 16340 battery as it states is 16mm in diameter and 34mm in length. So in order to fit the 16340 battery in the compartment for the 3AAA power supply some modifications have to be made.

First of all i cut the one of the three plastic pieces that connecting the top and bottom of the 3AAA power supply.

Next i measured 34mm inside and trimmed using a cutter and a chisel so the 16340 fits inside.

After that i used a 3.5mm drill, drilled a hole in the negative pole and fitted inside a screw. I measured the screw and cut it so the battery can fit without force inside.

I secured the screw with a nut and put another nut at the end of the screw. I put the battery inside and turned the nut until i had good contact without stretching the plastics, and then soldered that nut.

And that is all. No more AAA batteries for the flashlight.

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    2 Discussions


    5 years ago

    On Amazon it's showing the 16340 battery has 880mAh that would even make it more efficient of a battery that the AAA.....

    And if you did a little bit of hacking you could put a port on the bottom so you could plug a small solar panel in and charge the batteries like that ... Just build a little circuit to not overcharge, allow backflip of electricity and not push to much electricity to fast.

    At that point you could sit the solar panel in a window and charge it then have the flashlight ready when you needed it.


    Reply 5 years ago on Introduction

    Hi wpierce3 and thank you for your comment.

    in a future project i will add a usb charging unit in order to charge
    it using a pc, or in the car using a usb adapter or using a solar panel
    without taking the battery out.

    I also remind you that previously
    inside were 3 AAA batteries with cumulative energy capacity of 3x700mAh (claimed)
    and now there is only one with 1200mAh (also claimed).