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I wonder if these arguments take into account decreased battery life with a smaller battery in a plug in hybrid. From what I know about li-ion, the larger batte

I wonder if these arguments take into account decreased battery life with a smaller battery in a plug in hybrid. From what I know about li-ion, the larger battery should expect many more charge cycles before degradation than the smaller one, given the same power draw. There would have to be some kind of argument that the bigger battery leaves capacity on the table during its life somehow, which would mean the battery is still expected to be useful when the car is retired?

throw0101a 5y ago
> I wonder if these arguments take into account decreased battery life with a smaller battery in a plug in hybrid. I would think that it would be primarily a function of how much of the battery is treated as a 'reserve'. If you have 10-20% set aside that is not "useable", regardless of total capacity, then you could get similar cycles. There's also the possibility for using super-caps taking some of the brunt for high discharge (2-4s) events which could help with longevity. How expensive are they for these type of use case?
- nkingsy 5y ago
  80-20 cycling is important, but discharge rate is as well. If each cell in a 15kw battery discharges at 1c to move a car, each cell in a 45kw battery discharges at .33c. Same goes for charging. Might be diminishing returns, but discharge rates over 1c harm longevity. https://www.osti.gov/servlets/purl/1397110 https://www.osti.gov/servlets/purl/1397110
NathanielK 5y ago
It really depends on the battery technology. Lithium-Titanate batteries are starting to be used in hybrid vehicle powertrains. It is much lower energy density than typical BEV batteries. It is also rated at 20x the cycles and can be charged and discharged very quickly with minimal issues. The technology has come a long way from the NiMH cells that die after a decade.
JKCalhoun 5y ago
My laymen understanding is that all EV batteries are composed of lots of smaller cells. So a larger Tesla battery is simply more cells, not larger ones. That would put EV's and hybrids on the same level.
- chipsa 5y ago
  Generally speaking, yes, a larger battery with the same technology is more cells, not larger cells. But the larger battery will use less of each cell's capacity for a given distance driven. So it will cycle each battery less, comparatively.

throw0101a 5y ago

> I wonder if these arguments take into account decreased battery life with a smaller battery in a plug in hybrid. I would think that it would be primarily a function of how much of the battery is treated as a 'reserve'. If you have 10-20% set aside that is not "useable", regardless of total capacity, then you could get similar cycles. There's also the possibility for using super-caps taking some of the brunt for high discharge (2-4s) events which could help with longevity. How expensive are they for these type of use case?

nkingsy 5y ago
80-20 cycling is important, but discharge rate is as well. If each cell in a 15kw battery discharges at 1c to move a car, each cell in a 45kw battery discharges at .33c. Same goes for charging. Might be diminishing returns, but discharge rates over 1c harm longevity. https://www.osti.gov/servlets/purl/1397110 https://www.osti.gov/servlets/purl/1397110

NathanielK 5y ago

It really depends on the battery technology. Lithium-Titanate batteries are starting to be used in hybrid vehicle powertrains. It is much lower energy density than typical BEV batteries. It is also rated at 20x the cycles and can be charged and discharged very quickly with minimal issues. The technology has come a long way from the NiMH cells that die after a decade.

JKCalhoun 5y ago

My laymen understanding is that all EV batteries are composed of lots of smaller cells. So a larger Tesla battery is simply more cells, not larger ones. That would put EV's and hybrids on the same level.

chipsa 5y ago
Generally speaking, yes, a larger battery with the same technology is more cells, not larger cells. But the larger battery will use less of each cell's capacity for a given distance driven. So it will cycle each battery less, comparatively.