Notebook Akku Hot-swapper

by Matt Rechenburg, 14.01.2006

deutsch

Instructions how to build a "Notebook Akku Hot-swapper"

The "Notebook Akku Hot-swapper" is a device
which allows to exchange the rechargeable battery
of a Notebook during runtime avoiding the need
to shutdown/poweroff the system before the exchange.

Screenshots :

The scenario :

Like many people I am using a notebook for mobile work and I was never satisfied with the live-time of the rechargeable battery. When I bought my notebook I immediately bought a second battery, too, to double the live-time and to be able to work longer.

The problem :

When the power of the first rechargeable battery gets low I need(ed) to shutdown/poweroff the computer, then exchange the battery with the second one and power it on again. This always takes long time and re-opening all applications and logins again takes long time.

The solution :

A mobile device which acts like the regular notebooks power-supply - the "Akku Hot-swapper" !
If the first rechargeable battery gets low, plug in the "Akku Hot-swapper". After its plugged in, the notebook will use the power supplied by the "Akku Hot-swapper" and the (nearly) empty battery can be exchanged with a fresh one.
As soon as the fresh battery is plugged in the "Akku Hot-swapper" can be plugged off again.

-> The exchange of the battery can now be done during run-time !

-> No need to shutdown/poweroff/boot-up/re-login/... etc. any more !

-> Saves a LOT of time (and nerves) !

Instructions

"Stuff" needed from your electronic shop :
- 32 small rechargeable batteries (1.2 V / 2450mAh)
     -> look for "good" ones, normal non-rechargeable battery won't work
- battery-packs/boxes for the 32 batteries
     -> look for packs/boxes a 2 X 16 pieces
- small set of cable-clips and cables
- a connector/jack the same size as your notebooks power-supply

Tools needed :
- soldering iron
- cable nipper
- voltmeter (optional but usefull)

Skills needed:
- Understanding of the basic electric rules
- Two left hands able to solder cables

Build time :
- less than 1 hour

Pre-checks :
Use the voltmeter to measure the exact values of your notebooks power-supply.
-> mine is supplying 19 V / 4700 mA
Calculate the exact needs of the rechargeable batteries
-> I tried it first with just 16 batteries wired in row
     (16 X 1.2 V = 19.2 V)
     but it failed because of too less power strength !
-> 2 packs of 16 batteries wired in parallel then worked fine

Assembling :
1) Solder the battery-packs with cables. The matrix is :
- 16 batteries wired in row
- 2 X 16 batteries wired in parallel
(screenshot of the wiring)

2) Solder the connector/jack fitting to your notebook.

3) Put all 32 batteries into the wired battery-boxes

4) Measure the resulting power at the connector/jack
- it should be about 18-20 V
- be sure it has the same "power-direction" as your original      notebook power-supply-connector !
(screenshot of the measuring)

5) Assemble everything in a box
(screenshot of the assembled box)

... and now you are finished building your own "Notebook Akku Hot-swapper"

Hope you have fun with this HowTo and that it is usefull for you !

Matt Rechenburg

Disclaimer

Everything explained here is without any guarantee !
Use this documentation at your own risk and feel free to contribute
your own ideas. The Author of this text is not responsible
for any mistakes and their consequences while using this documentation. This document is licensed under GPL.