Gen II Prius low gas mileage, Constant battery charge.?

Dan · 11 Feb 2011, 11:39 pm

I have been diving an 06 prius for about 6 months now and usually get 45 or so mpg. However, I just bought a 05 prius for my wife with 50,000 miles on it. It was averaging about 42 at first, but after a long trip from miami to atlanta, it suddenly won't get above 32-33. It seems to have great power, but it is constantly charging the battery, even though the info display says the battery is full.

Hank Scorpio · 11 Feb 2011, 11:54 pm

Take it to the dealership those batteries have a 100k/8 year warranty and it's probably the battery that won't hold a charge. No one on here (myself included) is qualified to work on the electrical systems on these hybrids and because of the hybrid voltage someone with zero mechanical or electrical systems knowledge should never touch a hybrid. What's worse? 200 dollar diagnostic fee at honda or a 40,000 dollar hospital bill?

JerryJ · 12 Feb 2011, 12:09 am

Are you sure that you haven't accidentally put it in B rather than D? The symptoms you describe match running in B mode:

1. The engine runs all the time.

2. The battery keeps being charged.

3. MPG drops to the thirties.

Also check tire pressures. Low tire pressures will do that too. Many Prius owners like to run 44/42 in the OE tires.

While it's possible there is a problem with the traction battery or the battery ECU, these are extremely rare and almost always cause warning lights to appear.

If you have a Scangauge ( http://www.scangauge.com/ ) read the codes and post them to the Yahoo Prius Technical group.

wondering · 12 Feb 2011, 12:24 am

Adding to Jerry's list:

4. Cruise control is disabled.

If it isn't B mode try resetting the system by disconnecting the 12V battery for 15 minutes. You will have to re-enter radio presets and retrain the driver's power window but it may help.

Gen II Prius low gas mileage, Constant battery charge.?

Welcome to our forum

Quick member login