That hasn't really been true for years. At the same temperature, FePO4 outperforms lead acid in voltage, discharge current, and capacity.
> Operation below freezing ambient temperatures requires a heater and heaters need energy.
No. Charging requires a heater, discharging does not. It's really not reasonable to say "operation" requires a heater. While you're discharging, you're worried about the capacity and duration, and running a heater is a huge problem. The slower your discharge, the more of an issue it is to run a heater.
While you're charging, it usually isn't. You're already losing plenty of power to the charger inefficiency, it just takes a little more power to keep it above ambient. If you're plugged in it's irrelevant.
Fair point that only charging requires a heater but how does that meaningfully address the issue of cold weather operation? A battery requires charging and discharging and being able do to one but no the other won’t cut it, surely? The loss of capacity to heat is significant - often 10-30% capacity but that figure depends.
Also, i’m not sure plenty of power is lost to charging inefficiency. most industrial inverters operate at nearly 90% efficiency. Besides, above ambient isn’t a good metric - lithium chemistries do well around 10-25 C. If ambient is - 5 C, a delta of +5 C doesn’t change my core point.
Even if you are plugged in, lithium batteries aren’t dissipating heat. Not sure what the charger inefficiency has to do with this because that heat often isn’t the batteries themselves.
> The loss of capacity to heat is significant - often 10-30% capacity but that figure depends.
But it isn't a loss of capacity (although there is also a loss of capacity due to cold, in any chemistry). The capacity is the same, it just takes more energy to put the same amount of energy in. If you are putting energy in, you usually have an oversupply, and heating the battery is not an issue.
> If ambient is - 5 C, a delta of +5 C doesn’t change my core point.
I used the phrase "above ambient" specifically because the battery does not need to be warm unless you need to charge it quickly. If it's above 0 Celsius, it can charge. The warmer you make it the faster you can charge it. If the wasted energy is an issue you can charge slower.
> most industrial inverters operate at nearly 90% efficiency.
An inverter is significantly simpler than a battery charger. FePO4 charging can start as low as 2.5 volts and go past 3.6 volts. Making a converter with a 50% swing in voltage is not particularly easy. This higher-end charger picked at random[1] drops to <75% efficiency at the end of charge.
> Operation below freezing ambient temperatures requires a heater and heaters need energy.
No. Charging requires a heater, discharging does not. It's really not reasonable to say "operation" requires a heater. While you're discharging, you're worried about the capacity and duration, and running a heater is a huge problem. The slower your discharge, the more of an issue it is to run a heater.
While you're charging, it usually isn't. You're already losing plenty of power to the charger inefficiency, it just takes a little more power to keep it above ambient. If you're plugged in it's irrelevant.