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Counting & sorting
Counting & sorting
It's important you choose which configuration will suite your needs. You don't need 48V if your max. load is 500W. A 48V/5000w inverter has a 70W idle load, a 3000W/24V has 40W idle load. For serious installs The 48V is the only way to go. 48V will reduce the wire size significantly. 48V needs 14 packs in series. (14*3,7V=51,8V). My packs are 80p, stands for 80 cells in parallel. These packs are managable
80p weighs +/- 4kg and is managable on size and formfactor. Remember you need a whopping 1120 batteries to complete the install. For larger packs you need motivation and dedication to complete the powerwall.
Sorting, take this step seriously
Sorting, take this step seriously
After charging and testing the batteries, it's time to sort them into packs. This is a very important step in the process. I've seen well known builders skipping this part and buying a 1000$ BMS system to keep their packs balanced. If you test your batteries thoroughly and sort them properly your packs will stay balanced. After six months and more then 600Kwh generated power, my packs are still within 0.02V. Many use the Repackr tool to distribute the cells over the packs, but for a 14S 80P this is time consuming. A much faster approch is taking the batch with your highest cells ex. 2900-2999, sort them in piles of 10mah difference.
Sorting the batteries
Sorting the batteries
Don't wait to put the 18650s in the holders when all cells are sorted. Do it every 20 cells or so....If you make a mistake you can put it right.
Random batch
Random batch
40 cells between 1900-1990. Let's make a pack 4s 10p. Sort all cells by 10mah like I did above.
Start sorting
Start sorting
Start with the highest numbers. 3 cells with capacity 1990mah. Camera didn't seem to like purple cells on a blue background :-)
ssssnake wise
ssssnake wise
Continue with the other cells 1980, 1970, .... Left, right, right left, just like a snake.
Oh, this goes fast
Oh, this goes fast
40 seconds left to complete the whole batch under a minute.
Done
Done
All cells are sorted, let's see if capacity is the same in every serial batch.
Well, I can live with that. only 10mah difference per pack. Sorting took less then a minute. This way I sort all my cells for 14s 80p, all pack remain very well balanced.
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