Thursday, 1 March 2018

More ideas

We went out shopping today and whilst Jan was successful my efforts to buy a cheap aerosol of compressed air to clean the laptop fan proved fruitless.  Consequentially the laptop repair project is on hold. 

However I decided to start on my Lithium battery project.  The idea is to make a Lithium battery bank with enough storage capacity to power a house.  We would have 5kW of solar panels on the roof which would charge the battery bank when it’s dark.  Perth receives a large amount of sunlight which I believe makes the idea viable.  Before launching myself into this major project it seemed prudent to attempt something smaller and I’ve decided to repower the batteries of my old Panasonic portable drill.


It’s more than a decade old and had replacement batteries before we left for the UK in 2011.  Since returning I’ve discovered these batteries are also now dead.  The battery pack does provide information on battery capacity which is helpful when calculating the required number of replacement Lithium cells.


I can probably increase the battery capacity slightly and give the drill more oomph!

The first problem was disassembling the battery pack.  Fortunately Lidl came to my aid.  We were walking through Lidl when I noticed a drill set and thought “that might come in handy” before slipping it into the shopping trolley when Jan was looking in the opposite direction.


Relief…… one of the bits fitted the screw heads.

With the battery pack disassembled it was possible to see the makeup of the Ni-MH cells.


All of this gets discarded except for the black plastic cap which contains the battery terminals.

My source for Lithium cells is going to be the battery from our old Asus eee netbook.  We haven’t used it since 2009 when we took it on our UK holiday.  The netbook will work from the main supply without the battery and I’m thinking of using it (the Netbook) to monitor the planned house battery bank.


I guessed there were between 6 and 9 cells in the battery.



Lithium batteries require a Battery Management System (bms) to be safety charged and individual cells are directly connected to the bms.  You can see the Netbook battery bms in the above photo.  I will have to discard it as it’s too long to fit into the drill battery pack.


I have six batteries, which should be sufficient to make one battery pack.  I’ll also need a replacement bms and have already purchased one from China.  This will fit inside the battery pack.


This is where the project now pauses whilst I wait for the bms to be delivered.  I also need to test the Lithium cells to ensure all six are OK.

Once I’ve made two replacement Lithium battery packs for the drill I think I’ll make a larger capacity Lithium battery for mum’s old mobility scooter.  This currently has a 12V lead acid battery which is also starting to get tired.  


Ade said...

Interesting stuff Tom reading with interest.

Tom and Jan said...

Hi Ade,

Are you also planning to 're-battery' a few tools?

Ade said...

No Tom just the post content I like and the eventual goal even more.