Decreasing Gas Mileage in 2002 Prius

[wwu123]

Originally Posted by mlibanio

Try changing the transaxle fluid, replace it every 60,000 miles, trust me it helps! Also replace the stupid Panasonic 12V battery with an Exide Spiral Cell Battery as I did, I got at least 2-3 mpg back. I thought it was the traction battery causing my mpg drop, it was that stupid Panasonic battery that I had to replace every 2 years. The spiral cell battery is amazing in temperatures as low as -24 degrees centegrade up here in Canada. Car was registering at least 12.3 volts in that weather. The Panasonic even when new would show 10.6-11V in similar weather.

Which Exide model did you use as a replacement? Is it around the same size as the original or did you have to secure it differently?

[mlibanio]

As long as you have the Panasonic Battery that came with the Prius, no modifications are required. It bolted right in with my car. The terminals are perfect, and the battery is warranted by Exide for 8 years. You can throw away the stupid vapour tube that Toyota has on the original battery as the Exide spiral cells emit no gasses. If you live in Canada, here is the equivalent. Canadian Tire sells the exact same one for $30 cheaper! The first pictures includes most features found on the extreme, except the one that fits in our car puts out 54 amp hours, while the Panasonic puts out a mere 37 amp hours. In -20 degree centigrade weather during winter time in Canada, the car still registered over 12.8V before startup. The Panasonic from Toyota in similar weather would register about 10.8-11.2 volts. Its a hugely impressive battery. Plus my mpg improved, and I don't have to replace the battery ever 2 years as with the stupid Panasonic one. Plus my Toyota dealership said they are going to look into advising customers about this battery as they tested it themselves and found that its far superior to the Panasonic in all conditions. Plus I have a 300W amplifier in my car, and it can go for over half and hour and the engine does not fire up to charge it. No problems at all. And I think I used the word "plus" enough times to kill a horse! HAHAHA!!! I guess I got carried away with my discovery!

[bwilson4web]

Originally Posted by mlibanio

As long as you have the Panasonic Battery that came with the Prius, no modifications are required. It bolted right in with my car. . . .

No shims? Which model?

I went with the Odyssey PC925 and still had to make some adapter jumpers. So far, works great. However, I want to replace my wife's 2010 battery with something with more capacity.

Bob Wilson

[wwu123]

Hmm, the Exide batteries look to be about 7" wide on the smallest dimension, compared to 5" for the OEM battery. The hold-down clamp doesn't look like it could take anything wider than 6" at best. The other two dimensions look like they can take the extra sizing...

[wwu123]

Originally Posted by wwu123

Hmm, the Exide batteries look to be about 7" wide on the smallest dimension, compared to 5" for the OEM battery. The hold-down clamp doesn't look like it could take anything wider than 6" at best. The other two dimensions look like they can take the extra sizing...

Ahh, OK, I read the older posts, so to answer my own questions, the Panasonic battery was the replacement for the OEM in the TSB, and I need the 04003-23147 aux battery installation kit which is larger and will fit the larger Exide battery.

[Angie]

I too was experiencing gradually decreasing gas mileage over the past year or two. Then, the check engine and warning light came on and the fault codes P3000 and P3009 were diagnosed indicating a battery leak. I decided to replace the battery after my dealer agreed to a 50/50 split of the cost. Since I received my car back 5 days ago, I have noticed a signficant improvement in gas mileage, some 7-8 mpg greater, despite the fact that the A/C has been on continuously over this past week. I am hypothesizing/guessing that as the individual cells begin to fail within the battery, some loss of power occurs with the resulting need for the gas engine to fire more frequently, thus the decrease in mileage. Since the car was still driveable, even with the warning light on, I was wondering if each and every cell within the battery eventually failed, would one be able to drive the car solely on gasoline?

[marcinchicago39]

Dear friends. I'm new on forum, from yesterday I have 2001 Toyota Prius with huge millage, over 170k. I don't understand what I see on consuption screen. My MPG is very high for Prius, it shows 19 mpg when I started engine in cold Chicago weather (around 40 degrease), after drived few miles when blue light with termometer turn off (what this light mean?) mpg changed to 27, is it my consumption for a right moment and my average will be better or it is what my car really burn and I only make max 27 mpg. If yes, why is so high? What should I check in my car to get an answer? I don't understand what my LCD screen show with battery regenrated, after I drive some yellow squares show up with letter E, it's growing, but never go higher than 1/3 high.
I don't have my owners manual, maybe someone can show me where I can find some instructions what screen shows. I really want to understand my car and I need your help with this, I want to thanks in advance for everybody who helps me.

[bwilson4web]

Originally Posted by marcinchicago39

. . . from yesterday I have 2001 Toyota Prius with huge millage, over 170k.

Welcome to the club.

Originally Posted by marcinchicago39

. . . My MPG is very high for Prius, it shows 19 mpg when I started engine in cold Chicago weather (around 40 degrease), after drived few miles when blue light with termometer turn off (what this light mean?) mpg changed to 27

The NHW11 (2001-03) Prius is inefficient when cold. As a general rule, we try to use:

• lower bumper air inlet block - I use a split water noodle but anything capable of blocking the inlet helps retain engine heat.
• 1-2 miles at 25 mph - try to run the car through slow-speed streets for the first 5 minutes at speeds of 25 mph and using "N" when feasible. When stopped at a light, shift to "N" to reduce fuel consumption until the car can go into Stage 4, full hybrid mode. At that point, the engine will automatically stop. Search the messages for "stages."
• 0-38, 45-65 mph - try to use these speed ranges. The lower range keeps the car in hybrid mode so the engine can cycle on-off as needed for high mileage. From 45-65, the vehicle is also pretty efficient. There is a hybrid control law transition at 42 mph and I try to avoid that speed or speeds close to it.

Originally Posted by marcinchicago39

. . . is it my consumption for a right moment and my average will be better or it is what my car really burn and I only make max 27 mpg.

Check my mileage.

Originally Posted by marcinchicago39

. . . If yes, why is so high? What should I check in my car to get an answer? I don't understand what my LCD screen show with battery regenrated, after I drive some yellow squares show up with letter E, it's growing, but never go higher than 1/3 high.

Try to drive so you don't have to apply the brakes and your mileage will improve. This often means driving at the speed limit and learning to find 'pacing' vehicles like large trucks to follow. Being somewhere first means coming in last in fuel efficiency. Patience and you'll do fine.

Originally Posted by marcinchicago39

. . . I don't have my owners manual, maybe someone can show me where I can find some instructions what screen shows. I really want to understand my car and I need your help with this, I want to thanks in advance for everybody who helps me.

Check Ebay for manuals, they come up from time to time. Also, consider having your transaxle oil changed. This can reduce your cold-weather rolling resistance. Also run the tires at the maximum sidewall pressure. Finally, check the engine oil level and make sure it is below "F" and above "E." Overfilled oil has a bad effect.

GOOD LUCK!
Bob Wilson