How many charging cycles before a battery needs to be replaced? Also, does the number of charging cycles supported depend on how deep the discharge cycle was?
The reason I'm asking is that a battery driven airplane was linked to a while back and they were calculating that each ~one hour flight cost $20.00 to pay for the new battery when it's required after so many flights.
Now that they are using batteries in "peaker" installations I'd imagine there are many short bursts of (deep)? discharge, followed by many short charging cycles. Does each charging cycle shorten the batteries life, or is it a function of the total Wattage that is cycled through the system?
Thanks
Terry
Terry,
Great questions! And these are ones still being answered!
The battery cell chemistry, cell size, thermal conditioning system, type and speed of charging and discharging are all factors in battery degradation, so there are no simple answers. And ths is why one battery does not fit all situations, and the characteristics of one type of battery may be quite different than another.
Battery management software can control depth and speed of charging and discharging, which of course will differ over different uses. A big utility battery farm will be sized and controlled to make best use of its capabilities without damaging it. I imagine the battery life estimate for an airplane must be kept very conservative, for safety’s sake!
Tesla is accumulating data on its EV batteries, which do have a liquid thermal management system, and which seem to be holding up rather well.
The data clearly shows that for the first 50,000 miles (100,000 km), most Tesla battery packs will lose about 5% of their capacity, but after the 50,000-mile mark, the capacity levels off and it looks like it could be difficult to make a pack degrade by another 5%.
The trend line actually suggests that the average battery pack could go another 150,000 miles (200,000 miles total) before coming close to 90% capacity.
Interestingly, high-speed, “Supercharging” of the Tesla batteries, even daily, is associated with
less degradation. (See link below.)
Tesla battery data shows path to over 500,000 miles on a single pack
https://electrek.co/2016/11/01/tesla-battery-degradation/In contrast, for example, the battery in the Nissan LEAF is merely air-cooled, and is known to degrade significantly in hotter climates.