There’s been confusion about why Ram put big 3.6 liter V6 as a range extender on the 2025 Ramcahrger. Surely that is terribly inefficient?
No, it’s not.
Ram states following specs: 92kWh battery pack, 145 miles of electric range and 690 miles of total range, 27 gallon gas tank.
Electric range of 145 miles with 92 kWh means electricity consumption of 63 kWh/100 miles. Full tank contains 920 kWh of energy and gives 545 miles of range. That is consumption of 168 kWh/100 miles. The electric energy needed for 545 miles is 343 kWh, so the efficiency of the range extender is 37%. The generator and electronics have some energy loss so the efficiency of the V6 engine is closer to 40%. That’s crazy efficient for a gas engine.
Why is it so high? Why not use smaller engine?
Engine efficiency is highest at relatively slow speed and nearly full load. That big V6 can produce the required power at low RPM but needs to work hard. That’s very efficient. Smaller engine would need to run very fast which decreases efficiency.
In summary the V6 is very efficient at this particular application which suits it very well.
Not German tax. California’s BEVx category - i3 is as far as I can tell the ONLY vehicle that ever tried to meet the requirements of the category.
The i3’s bigger problem was not that the REX was underpowered - it would have been fine IF it had been allowed to turn on earlier. By preventing its light-off until the very last moment, what SHOULD have been a requirement to meet average power consumption needs was replaced with a requirement to meet peak power consumption needs - and the engine was woefully unsuited to the latter. This was done to avoid “European company car syndrome” - a PHEV that someone never plugs in. (Turns out those statistics are completely different in Europe than the US because it’s common over there for companies to provide employees company cars AND a fuel card - so the employee always uses the gas engine because for them that’s “free”).
For comparison, the Volt, a vehicle that did not even carry a tow rating at all, had a “mountain mode” that would light off the engine much earlier (45% BSOC). A modern vehicle that does carry a tow rating could EASILY identify that a towed load was present and adjust turn-on/turn-off thresholds appropriately. (Ways to identify: Is the trailer lighting/brake circuit drawing current? Are you taking twice as much energy to accelerate to 60 MPH as you normally would? Are you taking far more energy to maintain steady-state speed than you normally would? If any of those are yes, light off the REX earlier.)
If you look at the controls in the Ramcharger there is a button to keep the battery fully charged with the engine.
Even more reason that the REX is oversized for the application.
That said I can understand the “don’t have a problem if the user forgets to hit the button” concern - but there are better solutions than doubling the REX size - such as automatically detecting towing so that the button is rarely needed unless you’re driving unloaded and expecting to start a tow with low battery.