Prime performance when EV battery is depleted

I did an 900 mile road trip last weekend from San Francisco to Mt Shasta to Crater Lake. The Prime battery in the HV range never fully depleted like the old Prius. If anything, since the battery is so huge, you regen back into the EV portion of the battery. I have never seen the HV portion of the battery dip below 75%. So pretty much, the Prime felt like it was just driving in HV mode with a full battery all the time with the car kicking into EV mode every once in awhile. For the trip, my EV ratio was 16% or about 144 miles. 49 mpg going northbound with mostly uphill and 54mpg southbouth with mostly downhill. The car had no trouble maintaining 75-85mph. I accidentally hit triple digits speed for 20 seconds. The can was not struggling and it was perfectly stable like it was at 75mph.

 

Take a Corolla wagon, and completely load it up. Now imagine that instead of the 2L making 168hp, it had an engine that made less than 100hp. Now drive that up a real mountain like Pike's Peak or the Alps.

It is possible to drain a hybrid's traction pack to the point that there is no charge in the battery available to help out. the gen1 Prius had a warning light for this occurrence. The performance of the car became like that of My little thought exercise. It became less probable in later generations, but never eliminated.

The OP was asking how the Prius Prime performed under those conditions; no battery aid, just the engine. The less probable part means that we haven't seen someone actually posting about how it does perform, but it likely worse than the older generations since it is heavier with about the same output from the engine. Though we do have someone with a Prime that has seen this behavior in their older Prius.

As a PHEV, the driver can intervene to preserve or generate charge in the battery so they can always have enough buffer there for the battery to help on steep climbs.

 

How steep does it need to be to happen in the PP or the Gen 3? I've driven the Gen 3 over Vail Pass and Eisenhower Tunnel grades - both ~7% - going 80 mph and didn't experience anything like that.

 

I would assume that if you put the pedal to the metal under any condition it would trigger eventually, assuming the top speed isn't software limited. If you got one of those fancy OBD readers you could measure power draw and calculate the conditions required.

IMO it seems like a theoretical problem... I'm not sure I could even test it on local roads. Maybe repeat quick accelerations uphill?

 

About the same power? I'm seeing 70 HP in Gen1, 76 HP in Gen2, then 95 HP in the Gen4/Prime.

"About the same" would refer to only the Gen3's 98 HP, where reports of such behavior are very scarce.

 

I don't think I have ever driven my car on a 7% grade hill going that fast. My experience of uphill battle is on my daily commute, probably more than the grade of 7%, but only half a mile long uphill going less than 30mph. In those situations, Prius (Gen3 or Prime) or Civic, or any economy car with a small engine, I felt the car was underpowered compared to our Sienna with 3.3L V6 230hp or Pathfinder Hybrid 2.5 L 4-cylinder but combined with battery motor producing 250hp.

 

No clue. As I said, I've never experienced it in the gen2, but the OP has, and that is why they started this thread.

 

Isn't it funny that people are skimming over the fact that the hypothetical situation that was causing depletion of the older hybrid batteries was involving a drive up to the top of a notoriously steep climb (Pikes Peak) in the USA?

The more realistic scenario from the early days of Hybrids was that of the Honda Insight trying to travel west on ( I think ) I-80. The gradual upgrade would eventually sap the Insight's battery, leaving it without sufficient power to handle the minor hills. My recollection was that while the Honda COULD recharge while cruising, it had trouble charging the battery and maintaining uphill speed at the same time.

The 1997 model of the Prius had a similar problem, but by 2001 that was totally resolved. I saw the infamous "turtle" on my gen 1 Prius only when two of the battery cells cracked and leaked, triggering an HV fault. I was still able to drive it normally on level ground.

 

I do remember previous threads in which various members here had the same complaints about their Gen2 Prii climbing I-70 in Colorado. Not all Gen2 owners, just a portion of them. And more commonly from visitors, not from local residents who had learned how to make it work those circumstances.

 

I had a first gen (HCH) Honda Civic Hybrid with their first gen CVT. It would run out of juice at Camp Sacramento, heading towards S. Lake Tahoe. I would creep up that last leg like a VW van; without the benefit of a manual transmission.
It got a little better, after the third software update. I'm pretty sure Honda locked/blocked out a larger section of the battery as reserve - because each software update, my mpg took a hit. I moved to a Prius C and never looked back...