robbob2112
Doing more research, mosty harmless
Thanks, a very great heads up!
we're not planning on a battery at this point, I've made small lithium batteries for skateboards and e-bikes, I'm slowly building an electric motorbike, and pretty sure I'll get someone with a solid track record to build the battery for that, and same if we ever do get a battery for the house. Seeing videos of bike and skateboard fires looks real bad, I can't imagine having 100s or 1000s of cells letting all that energy out, not good!
House batteries are LiFePO4 chemistry, skate boards and other devices are LiPo. The LiPo batteries supply their own oxygen when they burn and contain many more toxic metals typically. The do have higher energy density but are so much more reactive I wouldn't have them in my house.
For a LiFePO4 battery to be a problem it needs to have damage to individual cells which causes them to vent and off-gas. The primary thing to spew out of it is hydrogen. The others that come out are not nice, but not nearly as bad if you get them on your or in your lungs. That is only going to happen if you be working over it at the time of a vent. The easiest way to damage a cell in a garage or other battery bank is through incorrect assembly or overcharging them.
Once they vent there is no fire since they only reach 300f or so from the chemical reaction. Hydrogen spontaneously combusts at around 650f. So for a battery to burn it needs a spark from something, anything. There are some pretty cool youtube videos where someone sticks a cell with a digging bar and it welds itself into place and the battery catches fire from sparks. They forced the vent from overcharging it.
There are a mountain of ways to make a mistake and cause issues if you DIY a battery. Used to be they were way way cheaper to order everything and bolt it together verse just buying an off-the shelf flavor. These days it is either even or cheaper to buy a pre-assembled unit. That and if you are trying to pass an inspection for grid-tie your battery must be UL listed and certified to work with your inverter. So you don't need to worry about DIY on a battery.
Ideally you will want a battery bank to let you capture all the solar power you can during the day and then run off that all night. Start with a good energy audit and you can "right size" the system so you have zero export and also use zero from the power company. The trick is winter time production from the panels is only 30~40% of summertime.