MysanthropicBuilders
New Member
Long story short, looking to build an off-grid house with solar (Don't worry, I'm in the planning stages, construction starts in 2-3 years). Was planning on making my own ~30-40kWh battery bank with used 18650's. The problem is... We're talking about 4,000 or so individual cells. This isn't going to be a hobby, or a fun project... It will be my source of electricity, with only a gas powered generator for backup. I'm not an electrical engineer, but I'm also not an idiot... Which means I'm going to prioritize safety, and take everything slow. It also means I know really very little about this, and this post is more of a sanity check of "can this realistically be done safely" rather than "Hey, which parts do I need to make this happen?"
So... What happens when those cells inevitably begin to fail? Obviously I'll have to go around occasionally and remove any dead/dying batteries, but I'm worried about a cascade effect. One fails, puts slightly more strain on another one and it fails too, the two failing in the same pack makes that whole pack fail, suddenly all 4,000 cells are either paper weights or on fire... That kind of thing. Would a setup like this need constant monitoring and instant removal of dead cells to remain stable? Or would it just be a lot more work to set up compared to a server rack style battery pack? And if this can possibly be answered... Does anyone know about how long a 30-40kWh (assuming it was being cycled daily / every other day) pack made from recycled 18650's would last? Obviously this can't be an exact number (the pack could last 10 years or 10 days before 80% of the cells fail), but anyone with experience that could give me any sort of a ballpark would be appreciated.
So... What happens when those cells inevitably begin to fail? Obviously I'll have to go around occasionally and remove any dead/dying batteries, but I'm worried about a cascade effect. One fails, puts slightly more strain on another one and it fails too, the two failing in the same pack makes that whole pack fail, suddenly all 4,000 cells are either paper weights or on fire... That kind of thing. Would a setup like this need constant monitoring and instant removal of dead cells to remain stable? Or would it just be a lot more work to set up compared to a server rack style battery pack? And if this can possibly be answered... Does anyone know about how long a 30-40kWh (assuming it was being cycled daily / every other day) pack made from recycled 18650's would last? Obviously this can't be an exact number (the pack could last 10 years or 10 days before 80% of the cells fail), but anyone with experience that could give me any sort of a ballpark would be appreciated.