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Konnichiwa from Japan
A thousand thanks to Peter Matthews, Jehu Garcia, Daniel Römer and AverageJoe for all their invaluable contributions.

While I will enjoy a FIT rate of 34centsUS/kWh on my 17kWp rooftop PV installation for a few more years, I want to be ready long before it ends.
I've started testing retired powertool batteries (free from work, but sadly mostly 1300~1600mAh high power cells), as well as old electric bicycle cells (mostly 2000~2400mAh, 50USD/kWh).  Capacity tested 1100 cells so far, now waiting for self discharge tests and various parts to arrive before starting to build my project: a powershelf.   I will start with just 1 row of 14s70p (ca 6kWh), then add more rows ( =battery banks ) to hopefully reach 10p(14s70p) (ca 60kWh) in a few years time.  I'll be using some unique designs with 3d printed parts... expect pictures in a couple of weeks!
Cool,. Really nothing wrong with the power cells just you need double the number of cells. And if your getting them for cheap they will do nicely. Since you have monitoring check and keep track of how much energy you use over time to get a better picture of what you will need. Then start building your wall to suit
ajw22 likes this post
Yes, power tool cells are certainly usable, but far from ideal. These heavy duty batteries are constructed with physical abuse in mind. The cells are epoxied (the hard stuff!) together, thick tabs with strong welds, tightly packed into heavy duty plastic cases. The epoxy is impossible to get off the sleeve, so I have to cut out and re-sleeve every cell. Not to mention having to clean out all the concrete dust that somehow managed to seep in.
So compared to laptop cells => need 2x~3x more cells, each requiring double the effort to harvest :-(

The bicycle cells are very nice. Most are 2.2Ah cells in 7s4p, lightly spot welded, held together in plastic brackets, no glue at all. Just need a screw driver to remove the plastic parts and pliers to peel off the tabs.
But that's only like 250 thanks each... not much really these days, won't go far -  Big Grin

Welcome buddy  Wink

Nothing wrong with a 1300mah cell if new it was 1500mah & you have the space to install more.
ajw22 likes this post
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