Quote:
Originally Posted by Vman455
Additional electricity use does not necessitate replenishment with gas power if that additional electricity was recaptured from braking and otherwise would have been wasted as heat or used to turn the engine over unnecessarily. At issue here is this: do the braking events encountered by a "typical" hybrid driver justify a larger battery capacity? Toyota decided, after weighing a number of factors, that 1.3kWh was large enough in the Prius for most drivers and was the best compromise of weight, cost, packaging, longevity, etc. Does this mean that a particular driver like the OP can't benefit from an increase in HV battery capacity? Of course not. Perhaps his commute, like my parents', takes him down a mountain to a valley floor, generating more braking energy than the battery has capacity to store and he'd like to take advantage of that.
Without knowing the details of his use case, blanket assertions like "excess capacity is wasted" are inane--precisely because we don't know what constitutes "excess capacity" for his use of the car. It is entirely possible that a 1.9kWh battery would be necessary to store all the braking energy captured before opportunity for discharge on his typical commute, in which case 1.9kWh would not be "excess," just as it is entirely possible that another driver with an otherwise-identical car would be perfectly served by a 0.8kWh battery. We simply don't know. There have been plenty of times, driving in the mountains of Idaho and western Washington, and once in Tennessee, when I could have used a slightly larger battery in my car, and I presume the same is true for the OP.
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Your first statement would be true if the car was ever plugged in, but it's not. Every Joule of energy used in propelling this car is ultimately from gas. You can isolate portions of a drive and say "that's electric," but when you go back even just one step, you see it comes from gas. Oh, and filling that gas tank up is yet more evidence.
How did the car get to the top of the hill? - gas
What was sustaining the kinetic energy of the car before the energy was captured by braking? - gas
For a Prius, a 1.9kWh battery would capture 225' more potential energy beyond what a 1.3kWh battery will - assuming the entire range of usable capacity is available (typically only half is available), so a 50% increase in battery size will typically capture about 113' more potential energy vs. the standard. That seems pretty insignificant to me.
How do you know you could have used a slightly larger battery? I've just calculated that a 50% larger (way more than slightly) battery would only make a ±113' difference in captured energy. Were your ascents/descents all less than 113'? Were you monitoring battery performance data? Do you understand how these cars behave? Are you forgetting that most descents are offset by an ascent in the opposite direction - even if it's a week later on the return drive home?
Math can dispel a lot of myths. It can be used to fill in the "we just don't know" blanks when one is inclined to add a sense of mystique to an engineering problem where none exists.