Lead acid batteries are widely available, cost effective and have an extremely good safety profile. Getting similar capacity from lithium ion batteries is expe

Lead acid batteries are widely available, cost effective and have an extremely good safety profile. Getting similar capacity from lithium ion batteries is expensive, and the failure modes are quite nasty in comparison (nobody wants a high capacity lithium ion battery that undergoes thermal runaway, and yes, lipo helps). Maybe that will change over time as better battery chemistries are developed. Lead acid batteries have been around for ages and are well understood. I agree that if you're cycling your batteries, li-ion chemistries have advantage, but lead acid are great for standby use in UPSes.