4 ms·
Like making anything last, don't operate at the limits of its envelope. * Limit max temperatures * Reduce maximum currents in and out * For lithium ba
by sitkack 2y ago
Like making anything last, don't operate at the limits of its envelope.
* Limit max temperatures
* Reduce maximum currents in and out
* For lithium batteries, limit peak charge to 3.92V, do *not* charge to over 4.1V or 30degC
I can't find the specific research study, but NASA did a study that last I read was going on for over 30 years with a neglible drop in capacity by only operating in the flat portion of the charge/discharge curve. The result is that properly speccd battery packs (probably > 1.5x most battery packs) can last indefinitely. For my cordless tools, I get the largest modules I can (5Ah). I have a single slim 2Ah module for fitting in tight spots.
*edit, when using a cheap intermittent high current device, like a hand vacuum, apply a duty cycle, like 30 seconds on, 10-30 seconds off to prevent the internal battery pack from getting too hot. These kinds of consumer goods have the smallest battery pack that will outlast the warranty.
I really wish battery charge profiles were codified in QR codes on the modules themselves (besides existing on an I2C bus).
Short-Course on Lithium Ion Batteries https://ntrs.nasa.gov/api/citations/20190030819/downloads/20190030819.pdf https://ntrs.nasa.gov/api/citations/20190030819/downloads/20...
battery aging dataset (appears dead) https://c3.ndc.nasa.gov/dashlink/resources/133/ https://c3.ndc.nasa.gov/dashlink/resources/133/
https://www.nasa.gov/wp-content/uploads/2021/10/3-nasa_battery_workshop_nov_2019_high_power_li-ion_cells_final.pdf?emrc=4b6c1c https://www.nasa.gov/wp-content/uploads/2021/10/3-nasa_batte...
https://ntrs.nasa.gov/api/citations/19990032333/downloads/19990032333.pdf https://ntrs.nasa.gov/api/citations/19990032333/downloads/19...
- hinkley 2y agoIn the mid 00’s there was a set ACM papers about how a better scheduler in the OS could substantially improve battery longevity (lifetime and per charge) based on the observations that most batteries do worse the faster you draw current, and you’re better off load leveling to keep the discharge rate steady. So for instance instead of running the disk and CPU at saturation, reducing CPU use when disk was saturated and vice versa. The apparent speed of the system was affected less than the battery life was increased. About 5 years later Apple bragged about how their new laptops without discrete batteries were 2x the run time of the previous generation due to the batteries being 1/3 bigger, 1/3 more power dense, and the operating system being 1/3 better at managing battery life. I’m fairly certain the latter came from someone reading those papers and taking them to heart. They had an advantage for the next few years.
- muzika 2y ago3.92V is very conservative, that is a good voltage for long term storage even. It should be safe to charge to 4.05-4.10V regularly.
- sitkack 2y agoThe NASA research really does support a 4.1V absolute maximum, with every reduction in charge voltage a dramatic increase in battery lifetime.