Quote:
Originally Posted by Dan
Simple answer (already raised)... Conservation of Energy. No energy cycle is perfectly elastic, all energy conversion incur some loss. ....
...Don't confuse this with Thermal Efficiency. That's a different subject. This assumes you already have the energy. Do you use it or store it. I say use it.
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Correctly stated -- and you use it when you have it. However the larger engine and the larger mass of the TCH throws a change in variables into the mix. (This is, after all, a TCH thread). The change is that the larger ICE is less efficient at very low speeds becasuse it needs a minimum threshold RPM to produce power at all -- and when it produces power it produces more than is needed for the very low demand of low speed creeping. Therefore you either use the "extra" power not being utilized for propulsion and store it as a charge, -- or you loose it as heat. If you accept that you charge, you now have it, so use it as propulsion energy to increase the ICE "off" time at low speeds.
So, now in low speed scenarios we have "best case" == true glide with no current in either direction and ICE off, and "next best" == alternating between periods of traction motor low speed drive (yes, even accepting the inefficiencies) and ICE drive with recharge. Actually, once the battery is has reached its upper SOC threshold, the TCH will try to do this anyway either as traction drive or as motor assist. The only difference in the "next best" is that the driver is making the decision as to when to use the charge rather than the ECU, and can thus gain an efficiency increase by recognizing an opportunity to more effectively use the stored energy.