Peter Plaaswerf's Tesla Powerwall-Inspired Stackable PCB Design Houses Seven 18650s Per Board
Featuring built-in battery management and up to seven 18650 cells per board, the stackable design aims at a $15 price point.
Peter Plaaswerf has shared a PCB design for a homebrew equivalent to Tesla's Powerwall, a stackable design supporting seven 18650 batteries per board and costing just $15 per board.
Announced in 2015 following three years of development, Tesla's Powerwall aims to reduce or remove reliance on the power grid by placing large quantities of batteries on the outside of users' homes — charged either from the grid at off-peak times or from solar or other local microgeneration.
The popularity of the product, and its high selling price, has inspired a range of do-it-yourself equivalents, some based on LiFePO4 batteries, some based on hardware taken from a Tesla Model S battery pack, and many built from common 18650 laptop batteries — including a new design from Peter Plaaswerf.
"While I cannot afford a Tesla Powerwall," says Plaaswerf, "I’ve spent some time drawing up a PCB to house 7x 18650 cells in series. Each board has onboard Battery Management [with] Overvoltage Protection (per cell), Undervoltage Protection (per cell); Balance Charging; Overcurrent Protection; Main pack Fuse.
"Each PCB has pads that allow you to stack them on top of each other with some 25mm brass spacers, to increase the pack capacity by joining several 7S strings in series — for example stacking 10x PCBs gives you a 7S10P Battery. If you used 2500mAh cells, that would be a 21-29v 25Ah pack! Costs are looking good, in the region of under $15 per board, keeping in mind it includes the BMS circuitry, that’s pretty cheap!"
Plaaswerf is currently looking to raise funds for production, and has placed his design on PCBWay for those looking to order pre-made boards while also placing the design files on his GitHub repository for free download. More information can also be found on Plaaswerf's blog.