That's not the price of batteries in general, that's the price of Li-Ion batteries. Were Li-Ion batteries mass produced in 1991?
The classic example is light bulbs [1]. If you use naive comparisons of like goods across years, with weighting by percentage of expenditures, to measure consumer/producer price changes from e.g. 1890-1930, you'll see:
1. decreasing weight in the basket and increasing price of whale-oil lamps over time 2. increasing weight in the basket and decreasing cost of light bulbs over time
But what you won't capture is that these two goods are both providing lighting, and that the switch from one to another provides a sharp drop in the price of light that is not captured by the change in prices of either in isolation.
Here it's the opposite effect, in that looking at Li-Ion battery prices in isolation overestimates the deflationary effect on energy storage prices.
This problem has also popped up in the context of measuring US manufacturing output over time. Specifically, the correction factors used to deal with this are called "price deflators", and their inability to deal with the pricing and business model of computer hardware may have produced an incorrect impression that US manufacturing output is holding steady or increasing, when it's actually decreasing [2]
[1] "Classic" as in used to draw the attention of the field in this important 1998 paper: https://lucept.files.wordpress.com/2014/11/william-nordhaus-...
[2] https://research.upjohn.org/cgi/viewcontent.cgi?referer=&htt...
I wonder if there was any way to compute light emitted per source. Then you could calculate a price per unit of light and whale-oil lamps would be obliterated by incandescent light builds which would in turn be obliterated by LED light bulbs.
It's harder for something like batteries, where there are multiple relevant performance parameters to reduce to one utility heuristic. And good luck when the utility is subjective (clothes), still under study (food and nutrition), or ill-defined (media).
But there are qualitative changes that aren't captured by this -- street lights are brighter and whiter now than they were in the 1990s for example, and those were brighter than oil lamps before them.
https://www.humanprogress.org/how-the-cost-of-light-has-fall...
According to Wikipedia, they were preceded by two years by the first commercially-available nickel-metal hydride cells in 1989, so that would be an interesting point of comparison. Also nickel-cadmium and lead-acid have been around for a very long time.
https://en.wikipedia.org/wiki/Nickel%E2%80%93metal_hydride_b...
Lithium-ion was never a good idea due to the fire hazard (in a crash they would just straight up explode, not even just cause a raging uncontrollable fire like LiPo, just boom) and Lithium-polymer could not support the necessary discharge rates (which I believe was also true of li-ion at the time too...). Early LiPo packs were only rated to like 0.5C or 1C peak discharge - this means, for a 2 amp-hour pack, 1C would be a discharge rate of 2 amps. Even then the packs did not really do well at their rated discharge rates - NiMH packs were far more tolerant of abuse in terms of discharge rates, in some cases you could push well beyond the rated spec and they would take it for a year or two's worth of sessions.
I was an "early adopter" on electric R/C airplanes back in the day (this would have been like 2000-2004) and the early stuff I used was mostly repurposed stuff from electric cars. The changeover to 4/5 or 2/3rds sub-C cells was a big deal at the time, the first "good" packs I owned were something called "HeCells" around 1800mAH or 2000 mAH, I also used KAN 1100mah cells. What I finally settled on at the time were these Sanyo "1950FAUP" cells which were extraordinary performers - we could push those cells to 70-80 amps peak discharge and they would take it. So in terms of the way LiPos are rated today[0], that is 40C discharge. This would only be doable for short periods, but it is necessary for launch and climbout (when the motor is running flat-out and the wing is basically stalled). Without the ability to sustain those currents it becomes very difficult to launch. Even still we did not "taxi" them like a normal airplane (or a normal model airplane), just wasn't enough power to get off the ground without a paved strip.
We typically expected about 10-15 minutes of flight time if you were flying normally, maybe 8-10 if you were really hotdogging it. So that means we averaged about 6C over the course of a flight (higher during climbout, less during cruising).
Another unsung miracle is how much motor technology has improved over the same period. My early motors were, again, repurposed brushed motors from Graupner's electric car lineup. We later moved onto some brushed Kyosho "magnetic mayhem" car motors that could push even higher levels of current. There was a Czech company called "Mega" who was an early mover on small neodymium brushless motors and that was a big deal at the time, they were far more powerful and far more efficient. Nowadays you don't even think about it, they're just a commodity, but at the time even a small brushless motor would run you about $130 or so!
[0] (tangent but it's kinda weird that NiCd and NiMH cells have traditionally been specced in amps but LiPo cells are specced in terms of "C discharge", obviously it's trivial to move between the two if you know the capacity of the pack but there's a definite difference in "style" of how the discharge rates are represented here...)
I think I understand what you mean but there was also a unfulfilled requirement before 1991. Back then (I'm 50.5 years old) cells didn't explode but then they also didn't set the world alight in terms of longevity either.
We had Walkmans and crappy clones that drained the shitty rechargeable cells we had at the time in a few hours. OK those things drove mechanical beasties - cassettes but cells/batteries were not particularly good before Li-Ion turned up.
Do you have any idea how something as simple as an iPod becomes exciting because no mechanical spinny things means power draw is much, much lower? It also helps if the thing isn't beige or grey. Apple are no more exciting to me than any other mob: design-wise, but they did get a few things right early on: "don't look shit". As it turns out, that simple mantra means that you get to >$1T t/o.
Now I own a phone that runs for around two days before charging. That doesn't sound too grand until you recall that just the GPS thing in it would have required 2U+ in a comms rack back in the day. The camera? If I kept an equivalent camera from the 1990s in my pocket then I'd be making silly jokes about it. The phone: I can stand on the top of Hay Torr and make a call.
https://www.ifixit.com/Guide/iPod+Classic+Hard+Drive+Replace...
edit: maybe not, plausibly just charging
That 50,000x or whatever didn’t really give any information about the growth of a product over thirty years, it only really gives information about the growth during the first year which if it had been marginally different would give you a wildly different value for your “market growth today” number.
We should all be careful not to publish large numbers with dubious sources.
NiMH came out around the same time and it's fine. A good one has similar energy to a good alkaline. Not very far behind a small-cell lithium ion either.
I will even venture that consumer lithium-ion batteries, such as for camera or laptop replacements, do not appear to have gone cheaper over last, say, decade. I can only assume healthy profit margin by brands (Nikon/Sony/Canon/etc, Lenovo/Sony/Dell/etc). Third party cheaper batteries are available, of dubious quality, so I suppose that may be a sign of cheaper manufacturing...
Power transistors for example I would also consider closer to alkaline cells than to logic, there has surely been a lot of progress in that field which eventually brought us the miracles of HVDC, but on a far more conventional scale.
The middle part of the S curve is when you see the dumbest articles about the technology, with people extrapolating the growth linearly and talking about how it will rule the world in a few years.