10 mpg loss --->SOLVED!

Thanks Guys.
I'm getting the feeling that the battery is not "Bad" yet, but is getting long in the tooth, and may need replacing within the next year or so, based on what you good folks have taught me.

I just ordered the D-51 optima battery kit. It did go up in price a couple of bucks from last week, (now $161.00) but my mechanic friend said he'll help me install it in his nice warm shop.

The dealer did not act like it was a warrantied part if it did go down the road.....so much for the 3 year "Certified Warranty" I paid more for when I bought the car. I figured that I do not want to wait until goofy things start happening or that the car would fail to start, then have to fight with the dealer at that time.

I'll report back with the results........hopefully it was not just money spent for something I don't need. I'm guessing I'd need it down the road, so We'll see.........

Frank D.

 

Hi Frank. Considering that it's probably fairly cold in NY at this time of year those results after sitting over night are ok (ok-ish). Knowing that the first tests (11.9, 11.8 volts) were after sitting for nearly a week is important extra information. The battery is definitely not in great condition but it's probably still serviceable (so technically I think your dealer is correct when he says it ok).

I get 12.6V, 12.3V (no-load, load) if I test it soon after driving, but it drops to 12.3V, 12.1V after sitting for just a few hours. That's with nice warm weather around 80F or more, so I think my battery is in similar condition to yours. I'll probably need to replace it some time soon, but for now it seems ok and I'm still getting good fuel economy.

Anyway it will be interesting to see if your mileage improves when you install the new optimo battery. Make sure you keep us posted on the results.

 

I sure will.
It's the least I can do for all the good help I've gotten here.....

Frank

 

I am finding these 12v battery threads very interesting and wondering if they apply to me.

I have a new 09 Package 2 that I got with 0 miles in April and have had all my services done at Toyota dealerships up to 15k which I am at right now.

I had a cheap aftermarket amp added, and audio control unit, and rear and front speakers.

After 2 or 3k miles or so I was doing awesome getting 53-55mpg and loving it, was hoping for a little better as folks stated that around 8-10k miles I could expect better.

Over the past two or more months, I have not been able to get the thing over 48 or 49 mpg. I know it is getting to be winter now, but it is so mild here in the Bay area, and I was seeing the decrease in warmer temps too. I check the psi pretty regularly so I dont think that is it.

Oil level looks good, and I had them do Mobil 1 synthetic 0w-30 after reading up on it here.

I just went out to my car after it has been sitting today since lunch 3 hours or more and tried the maintenance menu check on the battery and here is what I got.

No load = 12.1V
Load = 11.9V
Startup = 14.4 - 14.3V

Do I have a weak battery? Should I do some more testing? Bring it in to the dealer? Are my aftermarket parts (amp) sucking the life out of it - I use my prius very regularly so it never sits for more than a day or two - help?

My car is so new and I'm sorry to complain about 47-48 mpg when folks are getting worse, but I am conscious about my driving and definitely like to keep it above 50 mpg - let me know thanks prius people.

 

Losing a few MPG is perfectly normal in cooler weather.

That cheap aftermarket amp or faulty installation of same might be sucking power, maybe a lot, even when it is off. Either measure its current or disconnect it for a few days or weeks and see what happens.

 

I also want to say that I feel that the mpg was dropping before I put the amp into the car, although I did notice some weirdness with driver side power window after the install it would not automatically slide up with one touch. But the following morning it seemed fine.

Is it possible that I somehow left the acc on and drained the 12v battery and damaged it? I have never had to jump it but I have started it to find a low SOC, a month before I installed the amp.

I understand the change from cold weather in mpg but what do you think about the numbers I posted for the load and non load, does that seem low?

 

12.1 is below the normal 12.4 to 12.9, but, ehh, I couldn't say whether replacing it would improve anything noticeably. It's possible.

The car can help you remember to turn everything off and close everything, and so avoid the common battery-draining conditions: lock it. Always lock it. If something is amiss it will give a long warning beep. And don't use ACC for more than a couple minutes.

 

My numbers are nearly identical to these, measured via CAN-View and the car's own MFD-based maintenance mode (the two are in very close agreement). I plan to measure voltage directly with a digital meter this weekend (unless we get hit with a snowstorm, as the latest weather forecast suggests.)

For the time being, let's assume the directly-measured numbers will also agree. Richard (or anyone else), are you willing to speculate how long before I have to replace the battery? The car is a little over four years old now.

BTW, I'm seeing no observable fuel economy hit or other symptoms of impending battery failure.

 

I don't dare guess when it'll die, but I would start saving up for it :_>

 

Thanks for all of the reassurances and info. I think my mpg drop might have been just due to a stretch of cold weather and I had a freakout!

I think the switch to 0w-30 oil might have helped out because I filled up at a Shell station yesterday and over the 23 mile drive home I got 55.5 mpg.

 

Wow......I think if I got 55 mpg I'd wet my pants. I've never seen anything close to 50.......

I'm approaching 60k on my 2007 Prius.....I think I'll change to Synthetic oil, and perhaps there is more maintenance things that should be done that may help my mpg. I read something here about tranaxle oil.....not sure if that is tranny fluid or gear oil, etc? I'll have to look into that.

The new optima battery should be here any day...... we'll see if that helps.

Frank

 

lol frank, I think the weight of the oil might have made a difference? I read up on another thread about reports of people getting higher mpg's in colder weather with 0w-30, so I bought a jug of mobil 1 0w-30 synthetic and gave it to them when I brought'er in for 15k service.

I can't say whether or not that made the difference, because some folks stated that after they filled up the gas tank, after changing the oil they started to see the change. If you read up on oil change threads I found lots of useful info.

 

Just a note...I ordered my optima battery less then 48 hours ago, and it came in today......from California to NY....pretty impressive.
It's 10 degrees here, so I'll wait until my Mechanic can get me in....My next day off is Monday, so it will be next week.

Frank

 

what does this extra coverage provide? most dont cover any "wearable" part like brakes, tires, batteries (traction battery is an expensive exception) fluids, etc.

 

BTW, your window issue... when they put the amp in they may have disconnected the battery or pulled a fuse or something like that. After that, you need to recalibrate the window.... it's in your owner's manual.
You may also need to get rid of the back up beep again (if you had done that), reset which doors open with your sks (if you changed them from the default) and reload your phonebook if you bluetooth with your cell. Pretty much, the car returns to default and the windows forget where closed and open are if it loses 12v power.

 

EDIT - deleting my post, already covered by another response.

 

My 03' prius ran perfectly for 6 years without even a warning, then I brought it in for new tires, new 12v battery etc. The next day it would not start and had the fatal screen of death. I threw a charger on the new battery for a couple hours and it fired up again ok, but now after sitting overnight in 0-10F on first turn of the key, everything gets real dim but then it starts. I think the dealer gave me a relatively uncharged $190 battery and the vehicle is having a hard time charging and keeping it charged in the cold wx. I highly suggest getting the scangauge to reset any erronious codes that come up with a low 12V battery. If it weren't for scangauge I would have had to tow the car multiple times now. Keep in mind the 12V battery powers all ecu's and sensors etc. If the voltage gets too low you will have many error codes during startup..Only after the ICE starts running will it charge at 13.8V. No scangauge - The dealer would love you!

 

Just an update. We installed our new optima battery kit today with no problems. I'll post another update to let you all know if my mileage gets any better.

Frank D.

 

Frank, either 0W-20 or 0W-30 helps with mpg's. Our short trip MT cold weather driving improved about 5% using lighter visc. oil. That, along with an EBH, and grill blocking makes a big difference, and gets the heater up to warm temps too.

.

 

Thanks Hill!
Funny you should post that. I was just looking through the forum on the correct oil to use. I have my next oil change in about 800 miles, and I want to switch to synthetic. I have about 57k miles on the Prius now.

My tires are at 44/42...I used foam to block the upper grill, and I just changed the battery to the optima. I also have the oil at 1/4" below the top dot.

My problem with the oil is that I live in cold western (outside of Buffalo) New York. I drive the Prius down to my Florida home twice a year, and back, in April and in October. So 10 months in NY, two months in Florida.

So I need an oil that will work well in BOTH places. I'm a bit afraid to use a 0 weight oil. I was thinking a Mobil One 5w-20 or 5w-30.....I'm not sure what would be best for this unique situation. I'm thinking that Synthetic would be better. Except for the 1300 mile trip, I do not put too many miles on the car. In two years I'll move to Florida full time and never see snow again.

Thank you everyone for your good, kind help.

Frank D.