SOC for Long Road Trip

It depends on the type of driving over that 2 or 3 days. If you have short trips that would require cold engine starts, save the EV miles to avoid those "first 5 mins warm up MPG hits". It is better to use EV miles for those.

For long term storage, the owner's manual suggests you use up all the EV miles and store the car in HV battery level.

I don't think a week is considered "long term" but that kind of hints what's better for the battery.

No.

If you have EV miles left, the car will start in EV mode -- no engine start. If you run out of EV miles and forced you into HV mode, the engine will start the next time you start it up. If you anticipate upcoming short trips, keep a few EV miles.

 

Yes, that's why it's advantageous to save your EV. And not use it all up.

I'm going on a road trip to San Diego next month. I plan to use EV for the 1 mile from my house to the freeway exit. Then I will HV the whole way. I'm absolutely sure at gas fill ups and traffic, I will be able to use up EV. If there is any remaining when I come home 4 days later, then I will use it up on the freeway before I get home. The strategy is to use ICE for high speeds only. I average 60 mpg in HV mode that way because its almost 100% high speeds.

 

Very good description of the alternating use of EV and HV. Many of my trips involve significant hills/mountains. I find that my plug-in gets about 20% better mileage on these trips than my previous Prius Three. The reason is easy, going uphill in HV is pretty much the same gas efficiency as the non-plug-in. Going downhill you easily pick up significant SOC to be used where it is most efficient, slower flat parts of the trip. Of course if your trip is all flat interstate highways there is little advantage.

 

Why can you glide downhill Faster in a plug-in than in a regular Prius? And if true, why is that more efficient than increasing the SOC for later use?

 

The PiP can stay in EV mode up to 62 mph. Going downhill, I've seen as fast as 64, maybe 65. The regular Prius can only stay in EV mode up to 42 mph. The PiP weighs more so regen is higher. And finally, the PiP has a larger battery to regen should the regular Prius battery capacity be exceeded.

I assume that's why EPA for the PiP is rated 1 mpg higher for freeway than the regular Prius.

 

The HSI consumption indicator will show 100 mpg (hence actually possibly higher) without being in the EV mode for either type of car going downhill or just decelerating on the flat. Perhaps the mpg is actually higher in the PiP under those circumstances. I'll check with my ScanGauge II next time I get a good long downhill. Of course charging the battery is not "gliding" and the PiP is much better for battery charging as you indicate. Don't forget the extra weight advantage going downhill is a disadvantage going up the hill

 

That's the Iconic model (Gen3). The current has a limit of 46 mph.

It's only 123 pounds, not enough to be significant. The big difference comes from the battery-pack being Li-Ion instead of NiMH.

Watch what happens in HV mode. Even then, you'll see that the MPG is higher when going down a hill at 55 mph.

I compared my 2010 to the early plug-in model (check my August 2010 blogs for detail) and was absolutely delighted to see the efficiency had been improved even when not in EV mode.

 

I notice more regen braking when my wife is in the car. So, unless you're calling my wife fat... 1 mpg is hardly noticeable. But 123 pounds does make a difference.

 

Plug-in-Prius Curb Weight 3165 lbs
Prius Curb Weight 3042 lbs
123 lbs weight difference due to many more batteries some of which is compensated by the non-existent spare tire. I don't think the type of battery makes much if any weight difference, its the large amount of batteries.

 

Another contributor is the driving of the particular person. My best friend points that out on a regular basis, stating how the engine rarely ever shuts off when his wife is driving but does very frequently for him. Same Prius, same route... but the interaction with the pedal isn't the same between the two of them.

 

What kind of car does your friend have? I thought the idea was to avoid the EV mode in the non-plug-in because of conversion losses in and out of the battery. And would that be true in the plug-in once the "EV miles" charge is depleted?

 

Yes, unless you can can fully charge at your destination. I try to stay in EV mode if my destination is within a mile so I can use up all the battery before I plug in.

 

It's a 2004 Prius. He also owns my 2010 Prius now.

No avoidance when using EV in HV mode (known as "Stealth" mode). That electric-only driving is a major strength of the full hybrid system.

 

So why do many 'experts' (?) say "It may be counter-intuitive but encouraging EV operation makes worse mpg because of the conversion efficiency"?