Notebook Akku Hot-swapper




Introduction: Notebook Akku Hot-swapper

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.

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) !

Step 1: Stuff You Need / Pre-checks

"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

Step 2: Assembling

Solder the battery-packs with cables. The matrix is :
- 16 batteries wired in row
- 2 X 16 batteries wired in parallel
Solder the connector/jack fitting to your notebook.
Put all 32 batteries into the wired battery-boxes

Step 3: Measuring

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 !

Step 4: Put It in a Box

assemble everything in a box

Step 5: More Informations

Some more informations can be found at :



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    22 Discussions

    Why not go for the cheap 4-10k mAh powerbanks, disassemble them and use those high-capacity batteries instead of yours? It shortens the time needed to recharge and it boosts the recharging speed.

    My laptop needs a battery in it for the normal cable charger to work, so no "hot swapper" for me :(

    FYI, Mac users - all you guys need to do is put the laptop to sleep and swap the battery.

    2 replies

    Or do hibernate on a PC.It saves the contents of the RAM into your drive and then shuts down.Later it loads the data into the RAM so you just continue from the Change User screen.

    its ok if you have 32 spare batterys lying around. do it with 16 "size D" batts .good idea though

    it should also be noted that you need different amounts of rechargeables for different laptops,for example my laptops power in is 16V while my mom's work PC uses 18.5V.great i'ble by the way!cul:)

    My guess is that the hot swapper is only used for the time it takes for you to take out the battery and put in a new one. Also, dell customers should be aware that Dell puts a data cable in their AC adapters, which, seems to affect performance if you're not using a dell adapter. So unless you can replicate the data cable, running a laptop off a battery on the AC adapter port isn't a good idea.

    2 replies

    From my experience without the data wire it will accept power to run the laptop but it wont charge the battery but that was with dell chargers that had an internally broken data wire I havent tried it with a run of the mill power supply.

    Now I'm going to preface with the fact that I have not looked in to this my self but I would suspect that the dell cables actually supply a couple of different voltages and not a data connection. Now this is pure conjecture but I would imagine that its possible that dell has the power supply have 2 sub supplys one for charging the batteries and one for running the laptop, so that they can build the laptops with less parts on board. Now its also possible that the non dell adapters(aka cheap knock offs) just have the charging adapter and the laptop dos not detect that it is plugged in and runs with the default windows settings to optimize batterie life wile untethered.

    you can also use hibernation mode(my ibm does that when the battery is dead)(the laptop was so old it had nimh batteries)

    Clever- I like how it uses the laptop's built-in power management. This could also be done with a 12V SLA, an inverter, and a laptop's original power supply, in order to ensure clean power. SLAs have ginormous capacity, too..

    1 reply

    I have a old dell battery from a older laptop i was thinking of using that to power my HP laptop in the same setup as he does.

    I've been looking into building a similar project but I'm not going to use batteries for power. I am a little curious though, what sort of battery life do you get out of it when your using fresh batteries? How long can it power your laptop off the Akku Hot-swapper?

    This is cool... But the manufacturer I work for will not let you do that: If it can't read accurate battery level (or a set impedance between the poles) (Ie when you take the first battery out and before you've had time to insert the second one) it will assume the battery has a defect and will shut down everything in a panic, because we're shitting our pants that it might explode to the users face ! I work in the PDA industry but I assume it would be the same for laptops...

    4 replies

    you can take the battery out of a laptop at any time weh you have an external powersupply conected, which this esentialy is.

    it does this even wen its plugged in to a wall adapter? i have never had a laptop do this to me and i have used, worked on or played with about 5 or 6 major brands.

    It could be PDA specific then, Sorry I assumed a bit too fast that it would be the same for laptop...