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Although this is really easy to do and works quite well, I'm not sure a car battery is the best choice with the alternative battery chemistries that are availab

Although this is really easy to do and works quite well, I'm not sure a car battery is the best choice with the alternative battery chemistries that are available now. lifepo4 is probably the better choice but I'll just talk about lead acid batteries: Lead acid batteries are, at least IMO, no longer the best choice for a backup power source. I can think of several reasons to avoid using a car battery as a backup: 1) lead battery recycling is very environmentally unfriendly. 2) These batteries have pretty poor performance in deep cycle applications. 3) They require constant charging to maintain their voltage so power use goes up just to keep your backup battery topped up. 4) This constant charging, however, degrades the battery and reduces it's useful life. 5) Almost all lead acid batteries on the market are significantly lower quality than what used to be available a few years ago. They have an even shorter life expectancy than what's easily achievable because they are essentially designed to fail after a year or two.

the_biot 4y ago
Your first point is kind of negated by the fact that he specifically says he used a second-hand battery from a scrapyard. Indeed, what he's doing is a very good way to keep it away from any environmentally unfriendly process. I expect that in the somewhat near future, used EV batteries will have a similar second life as house electricity storage. You don't want an EV that's got half the range it used to have, but install it in a house and it's just useful.
bcrl 4y ago
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.

the_biot 4y ago

Your first point is kind of negated by the fact that he specifically says he used a second-hand battery from a scrapyard. Indeed, what he's doing is a very good way to keep it away from any environmentally unfriendly process. I expect that in the somewhat near future, used EV batteries will have a similar second life as house electricity storage. You don't want an EV that's got half the range it used to have, but install it in a house and it's just useful.

bcrl 4y ago

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.