Unusual improvement?!
 

(Sorry for the long post)

Something strange happened with my HCHII this afternoon! For two months of my 21 mile (one way) LA commute, mileage is always better in the AM then PM. I've posted before that the drive is flat, no wind and speeds are equal. Seems it often chooses the PM drive to do a forced regen, despite seven or eight bars on the SOC meter. Everything I gain in the AM I lose in the PM!

Today was different. My PM ride started with battery SOC unusually low (six bars), so I expected awful MPG results with forced regen all the way home. Interestingly, every time I looked down at the IMPG gauge, it was +55. Even accelerating (slightly) and up grades (overpass rises) I could do 50+. That NEVER happens! It was SO easy to keep the MPG up, and I don't have a clue why. My SOC dropped to four bars during the ride. I've never, ever seen it that low.

By the time I got to my exit, SOC was back to five, but the MPG was still good. On top of that, it was cool and gloomy in LA today. Totally unexpected results!

I'm currently on my 5th tank... at 585 miles and three bars of fuel left. Avg MPG for the tank is showing at 51.7 (my highest ever). Decent, and finally beating EPA, but it's sure been a struggle to get here.

It's been fun but somewhat frustrating. I see so many posts from folks who don't even seem to try hard (driving 65+, etc.) and get 50+ MPG. I've been driving like my Grandpa (and he's been dead for years!!) at 58 MPH and employing every hypermiling technique possible (including tires at 40 psi). It's a struggle to hit 52 MPG. When I have a drive like I did this afternoon, I wonder if there's something wrong with my car. How could it be SO much better today when absolutely nothing else changed?

Any ideas??? Why did the SOC get so low without a forced regen?

Re: Unusual improvement?!
 

As I was leavin the dealership with my HCH2 about 2 weeks ago, the salesman told me that he car would 'suck up a lot of fuel' initially, and it would take a few thousand miles for the all the systems to 'break-in' and get really high FE. I expect the worst, that the posted EPA numbers were not attainable, that his experience was that buyers expected to get close to 50mpg per the EPA estimates, and he was setting me up so I would not be disappoined. Having only a months experience with our Prius, and with the numbers well below the EPA city estimate (our highway FE exceeds EPA estimates even with the air on), I figured high 30's to low 40's initially.

To my pleasant surprise, the 14 mile trip home produced 52mpg (all city driving) I now have about 300 miles on the car, have averaged 63+mpg over the last 100 miles, virtually all city driving - all thanks to the fuel saving tips I have learned from this site.

I have read from numerous posts that the FE does improve after several thousand miles have been driven. Perhaps this is the case for you. perhaps there was a strong tailwind. Hopefully you will maintain this new higher FE!

You might want to consider raising your tire pressure to 44 (the maximum recommended on the tire). That might help a bit. I have also had my tires filled with Nitrogen. Most people don't think it helps with FE, but it might, and with these cars, every litle bit helps, and there is no downside. Here is a link to info on the Nitrogen:

https://www.greenhybrid.com/discuss/...5592#post65592



This link may be of interest to you as well:

https://www.greenhybrid.com/discuss/...tips.7702.html

Good luck!

Re: Unusual improvement?!
 

3 tank = about 1500 miles = engine more broken in?

I too have noticed this. It just keeps getting better now. I was originally at 49 and have gotten as high as 59 in 1 day of commuting since then.

Now I am just curious to see what happens after my first oil change (still have 40% to go).

Re: Unusual improvement?!
 

Okay, so here's today's result...

Back to normal (unfortunately)... with another little twist. When I arrived at my office in the morning, the SOC was five bars. When I started in the PM, it was EIGHT bars (full):confused: . Unless someone secretly came out and charged my IMA battery, I have no clue how that happened!. The eight dropped quickly to seven, and that's where it stayed for most of the trip home. As usual, coasting and even moderate acceleration yielded one green charge bar (forced regen), and an extra load I had to battle the whole way. I was able to maintain my 51.7 mpg through most of the ride home. Speed was pretty steady at 57.

Can anyone explain the mysterious SOC increase I had while my car sat for nine hours in a parking lot? (note: temp was maybe 10 degrees warmer than in the AM... not significant)? Thanks!

Re: Unusual improvement?!
 

Here's what I think I've read. Not sure where.
The SOC gauge is not based on constant measurement. It is based on a calculation, extrapolating your rates of assist and regen to figure out what the SOC should be. Every once in a while that SOC measurement is recalibrated somehow. I think the recalibration is done by letting the IMA force-recharge the batteries until they will take no more. It's not healthy for the batteries, so it isn't done all the time.

Or maybe this was all in my dream.:confused:

Re: Unusual improvement?!
 

Well, if that's true, I'm in for some trouble. "every once in a while" seems to be happening every day! Good thing I have a California warranty on that battery!

Re: Unusual improvement?!
 

At your next regular service, let them know what's going on; in fact call them and have them note your mileage and details in their records so that it's under their responsibility as well.

Remember, the batteries never fully charge or discharge, they stay somewhere in between. This gives the longest life to the cells. (I think Toyota does maximum 80% charge/20% discharge and Honda is similar).

Re: Unusual improvement?!