M1 MacBooks are ~5 years old at this point, and if you've been working a laptop hard for 5 years it's often worth getting an upgrade for battery life as well as speed.
The lower power and heat of M-devices might result in meaningfully longer battery life, and I'm curious to find out.
But I'd say that how much it's used is also an important factor.
I haven't booted up the older M1 recently to check, but I remember it was throwing replace battery warnings well before I got the upgrade and that I think that triggering below 80%.
I use Al Dente to further optimize battery and calibrate it now and then
I didn't have a spare laptop to work with at that time for a week so i held of[1]. This is probably a reason for lot of people opting out of upgrades.
After the M4 came there was hype for the new screen which performs better in sunlight and M1->M4 seemed worth it plus vRAM which is certainly handy.
[1]The screen was also deteriorating - no physical issues just wasn't as bright as it was new) and they said I should replace that too. The economics a new Air worth of money on a older laptop with just 1-2 years primary use life left is shaky.
Also both times I did it, it took 2-3 days, not the quoted 1+ weeks
2. Batteries age faster in the beginning and then their ageing rate plateaus. It's the same for electric cars. E.g. a Tesla can lose 5% efficiency in the first 30k miles, but will lose the next 5% over 60k+.
The only time battery is not a problem is when video streaming for hours, presumably the decoding is offloaded to the dedicated media chips on the board.
Also, the majority of time it’s been in my van, which is pretty chilly most of the time.
From my understanding, battery health is based on use and environment.
It typically runs around 110-130 for CPU and the battery is 85-90 on light usage like say browser or slack.
However if i run a full compile of the repo or just about anything a bit compute intensive CPU jumps easily to 170-200 range regularly and battery to 120.
I am now frequently running the fans higher manually to cool it down[1]
I think Apple is optimizing for being quiet over battery and laptop life and have kept the fans low speed even if it would benefit the hardware to speed them up earlier under load.
[1] This is not because I can the temps all the time in the top bar. The palm rests do become noticeably hotter and bit uncomfortable than the noise would be.
Then it started having issues waking up from sleep. Only the OG Apple charger could wake it up, then it would see it actually had 40-60% battery but something had gone wrong while sleeping and it thought it was empty.
Intel MacBooks had terrible SMC issues, so maybe this won't afflict the M-series. Just sharing because I could still use that MacBook a few hours between charged, it just couldn't be trusted to wake up without a charger. That's really inconvenient and got me to upgrade combined with new features.
It'll probably be around $200-$300 if you want an official battery. More like half that if you're willing to accept a 3rd party one.
Even if a local shop somehow sourced a legit, new Apple battery, why wouldn't I go to the Apple Store if it's the same cost and would only be the battery?
(For $299, Apple replaces the speakers, touchpad, batteries, top case, and keyboard and provides a parts and labor warranty for 90 days)