Quote:
Originally Posted by Philip Fisher
Yes but it doesnt give that much power back to the battery.
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Indeed, I just did a quick calculation. Take a 2.6 tonne V90 T8 travelling at 100km/h braking to 0 in 8 seconds. The kinetic energy the car has is near enough 1Meajoule or 0.27kWh. If we were to recover all of this energy, in 8 seconds, the battery would need to absorb all that power at 1250kW. For reference, the fastest quick chargers today support up to 300kw but no car currently can charge at this speed. The T8 can only support 3.7kW charging by cable. My guess is that under regenerative braking it can absorb more but still nowhere near the 1250kW needed.
This is where ultracapacitors come in, they can take very high current but don't have the same energy density as batteries. They're the perfect candidate for getting the most out of regenerative braking. I wonder if the B cars will use supercapacitors? Last year Volvo signed a deal with Maxwell for ultracapacitors.