It's a good question! For years I've been hoping for the legendary Lithium-ion Crossover Event after which lead-acid batteries become obsolete for all purposes, but the auto parts stores in my neighborhood are still stubbornly stocking lead-acid starter batteries for some reason; so, too, the burglar alarm folks. Maybe the Crossover has already happened in the developed world, by which I mean China, but the news hasn't yet reached Argentina?
There's really no benefit to lithium batteries in a car. They perform much worse in the cold, and they are more expensive. You don't cycle your car battery 100-0-100 so the fact that the useable capacity of lead batteries is lower doesn't matter.
Yeah, but the question is whether they are more expensive. If they were cheaper (per watt in this case, rather than per joule) people in Brazil and northern Argentina would probably use them to start their motorcycles. I think they're closer to that crossover than to the cost-per-joule crossover.
I'm not sure if you're being facetious, but in thinking about it I think you've pointed out the remaining advantages. Current from lithium batteries has to go through a bms (and thus you have to build them to a current rating, even if your cells are 5C the cost of BMS may make lead acid cheaper) and they have low temperature issues so I can see them being useful in current limited situations and in situations where not thinking about them or the weather too much is more important than capacity.
I can't see this recommendingnlead acid in a capacity limited application unless it's a situation like Australia where half of the local shops are pricing them at 2012 rates.
I'm not being facetious, I'm just trying to understand the discrepancy. Your explanation isn't it: battery management systems do not account for a major part of the cost, we don't have low temperatures in Buenos Aires, and the auto parts stores are not selling the lead-acid batteries as specialty parts to people who drive in from Patagonia to replace their car batteries, similar to engine block heaters.
sbp looked into the issue and it seems that lead-acid is still cheaper.
https://news.energysage.com/lithium-ion-vs-lead-acid-batteri... says, "The one category in which lead acid batteries seemingly outperform lithium-ion options is in their cost. A lead acid battery
system may cost hundreds or thousands of dollars less than a similarly-sized lithium-ion setup."
https://www.pv-magazine.com/2021/09/02/lithium-ion-vs-lead-a... says, "Citing previous studies, the researchers said that, for stationary energy storage, lead-acid batteries have an average energy capital cost of
€253.50/kWh and lithium-ion batteries, €[1555]/kWh, and that their total average power cost is €333.50/kWh and €[2210]/kWh, respectively."
In the units I was using above, those costs are US$68.30/MJ, US$419.0/MJ, US$89.86/MJ, and US$595.5/MJ.
So it seems like the answer is that, yes, lead-acid is still purchased by some people as a new system, because it's still cheaper than lithium-ion. Probably what led to the error is that lead-acid in Argentina is more expensive than lithium-ion in China, or wherever Schroederingersat's at.
Are those prices up to date? There are several shops in Brisbane AU that will sell drop in 12V batteris retail for 350USD per nominal kWh (about $320 per real kWh at 0.1C) including taxes. The occasional special is in the 250-300 range. Ebike batteries with higher current are in the 300-500 range.
They're highly unsuitable for an engine starter at that price though (1C BMS) and have no built in low-temperature monitoring. There are bigger systems with better safety features for about $400US/kWh available in europe and asia.
Also note that nominal capacity of a lead acid battery is often not usable capacity. I was assuming 50% DoD as usable daily capacity which may be pessimistic.
It's possible they're not! But I'm suspicious of this notion that prices have dropped by a factor of 5 since last year, and have reached Australia but not Just Catamarans in Florida; maybe they're doing the calculation differently than you are. Or maybe there's a fraud going on.
FWIW your US$320/kWh works out to US$89/MJ. (I try to use SI units when I can; it saves a lot of hassle.)
I think it's fair to exclude taxes, but not to include "the occasional special", since the retailer is presumably taking a loss in that case and will be unwilling to sell you an arbitrarily large number of batteries at that price.
A thing I wonder about is how big a Li-ion battery you really need for an engine starter. 200 amps at 12 volts is only 2.4 kilowatts; a 15C battery with 0.6 MJ capacity could do that, which is about a dozen 20700 cells. You do need a 200-amp BMS, but I think the cost of the cells is still the issue.
Are you correcting for usable capacity in your prices? 50% DoD was typical for lead acid last I checked vs 85% for LiFePO4 (or 100% if you're happy with it lasting as long as lead acid at 50%)
As to fraud, I've seen at least four batteries perform as advertised. Also a 5x disparity in prices between different shops is entirely consistent. Prices have been dropping rapidly and there are enough people who go 'oh yeah, that was about right 3 years ago'. Plus retailers may have paid several times current retail for their stock if it's a year or two old and was bought at prices that hadn't been updated for a year.
