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This is a significant step for affordable energy storage. However, a lifetime of 3000 cycles seems low for such a big investment. Does anyone have an idea how t

by goku12 3y ago

This is a significant step for affordable energy storage. However, a lifetime of 3000 cycles seems low for such a big investment. Does anyone have an idea how this compares with other solutions and how it would perform in under expected load?

CyberDildonics 3y ago
3,000 is more than the 2,000 of lithium iron phosphate, which is more than the 300–500 cycles of lithium ion. That is what they say the lifespan is, but it could just mean diminished capacity after that many cycles. Durability is important, because if you double the durability, you cut the cost in half over time.
- h0l0cube 3y ago
  Depth of discharge is curiously missing from their cycle count
  - CyberDildonics 3y ago
    Sodium Ion is a new chemistry that a lot of places are starting to sell. This is just one company. Cycles at 80% depth of discharge[a] Hundreds to thousands https://en.wikipedia.org/wiki/Sodium-ion_battery https://en.wikipedia.org/wiki/Sodium-ion_battery
    - h0l0cube 3y ago
      The depth of discharge affects the amount of cycles that can be achieved without a significant capacity drop (e.g., down to 80%). Measuring with a shallow depth of discharge can artificially inflate the cycle count.
      - CyberDildonics 3y ago
        I'm not sure what you are trying to say here, there is more information out there, I just copied from the wikipedia page. https://en.wikipedia.org/wiki/Sodium-ion_battery#Commercialization https://en.wikipedia.org/wiki/Sodium-ion_battery#Commerciali... 80% depth of discharge means to 20% capacity, not 80% capacity. You can see on that section that the lowest number is for 100% depth of discharge, which wouldn't make any sense if depth of discharge and capacity were the same thing. with good rate performance till 3C and cycle lives of 300 (100% depth of discharge) to over 1,000 cycles (80% depth of discharge). Another section says 5000+ cycles at 80% capacity https://en.wikipedia.org/wiki/Sodium-ion_battery#TIAMAT https://en.wikipedia.org/wiki/Sodium-ion_battery#TIAMAT
        h0l0cube 3y ago
        It's fair to say that between battery manufacturers cycle counts will vary. Like you said, sodium ion is a nascent technology with many new players, and improvements to battery technology could improve cycle count, but cycle measurement in absence of the DoD it was tested at makes it hard to know how durable the battery is under real-world usage. Li-ion and LiFePo can have insane cycle counts if you never go below 80%. To illustrate here's a diagram I found on the first Google result (though from 2017, batteries were worse then) https://www.researchgate.net/figure/Depth-of-discharge-versus-cycle-life-of-the-lithium-ion-battery_fig4_318292540 https://www.researchgate.net/figure/Depth-of-discharge-versu...
        CyberDildonics 3y ago
        I'm still not sure what you are trying to say. The wikipedia page compared various cycle depths. By that information sodium ion is more durable than lithium iron phosphate.
dzhiurgis 3y ago
> big investment Sorry, what? The _cells_ are ~$100/kwh on aliexpress. You are looking at residential batteries around the cost of an iPhone. Shipping + installation costs more. Sure Tesla still sells theirs for like $10k, but that won't last.

by goku12 3y ago

CyberDildonics 3y ago

3,000 is more than the 2,000 of lithium iron phosphate, which is more than the 300–500 cycles of lithium ion. That is what they say the lifespan is, but it could just mean diminished capacity after that many cycles. Durability is important, because if you double the durability, you cut the cost in half over time.

h0l0cube 3y ago
Depth of discharge is curiously missing from their cycle count
- CyberDildonics 3y ago
  Sodium Ion is a new chemistry that a lot of places are starting to sell. This is just one company. Cycles at 80% depth of discharge[a] Hundreds to thousands https://en.wikipedia.org/wiki/Sodium-ion_battery https://en.wikipedia.org/wiki/Sodium-ion_battery
  - h0l0cube 3y ago
    The depth of discharge affects the amount of cycles that can be achieved without a significant capacity drop (e.g., down to 80%). Measuring with a shallow depth of discharge can artificially inflate the cycle count.
    - CyberDildonics 3y ago
      I'm not sure what you are trying to say here, there is more information out there, I just copied from the wikipedia page. https://en.wikipedia.org/wiki/Sodium-ion_battery#Commercialization https://en.wikipedia.org/wiki/Sodium-ion_battery#Commerciali... 80% depth of discharge means to 20% capacity, not 80% capacity. You can see on that section that the lowest number is for 100% depth of discharge, which wouldn't make any sense if depth of discharge and capacity were the same thing. with good rate performance till 3C and cycle lives of 300 (100% depth of discharge) to over 1,000 cycles (80% depth of discharge). Another section says 5000+ cycles at 80% capacity https://en.wikipedia.org/wiki/Sodium-ion_battery#TIAMAT https://en.wikipedia.org/wiki/Sodium-ion_battery#TIAMAT
      - h0l0cube 3y ago
        It's fair to say that between battery manufacturers cycle counts will vary. Like you said, sodium ion is a nascent technology with many new players, and improvements to battery technology could improve cycle count, but cycle measurement in absence of the DoD it was tested at makes it hard to know how durable the battery is under real-world usage. Li-ion and LiFePo can have insane cycle counts if you never go below 80%. To illustrate here's a diagram I found on the first Google result (though from 2017, batteries were worse then) https://www.researchgate.net/figure/Depth-of-discharge-versus-cycle-life-of-the-lithium-ion-battery_fig4_318292540 https://www.researchgate.net/figure/Depth-of-discharge-versu...
        CyberDildonics 3y ago
        I'm still not sure what you are trying to say. The wikipedia page compared various cycle depths. By that information sodium ion is more durable than lithium iron phosphate.

dzhiurgis 3y ago

> big investment Sorry, what? The _cells_ are ~$100/kwh on aliexpress. You are looking at residential batteries around the cost of an iPhone. Shipping + installation costs more. Sure Tesla still sells theirs for like $10k, but that won't last.