Non-Technical Owner Requesting Help

First thing to check is the 12 volt battery, if you have the owners manual, there are directions on how to do that. If you are lucky that will be your problem.

 

I agree, and at 129k the hybrid should be good, you are up for spark plugs and drive train fluids, if the hybrid battery is failing, a rebuilt will slide right in, a read of the obd2 port is in order, a test of the 12v also

 

Welcome to Prius Chat!

First and foremost. Check the 12 volt battery. Take a look at the following link. Run the test after the Prius has set overnight. Please post all three (3) values.

Weird stuff happening? MPGs dropping? Test The Battery | PriusChat

If you do that, we can tell if your 12 volt is failing. A weak and or dying 12 volt can cause all sorts of problems.

Concerning the traction battery. Until the dash lights up like a Christmas tree, there is nothing that can be done and should not be worried about.

So with that said, check the 12 volt battery first.

Ron

 

When was the last time you checked your tire pressure? I've seen customers go over a year without checking.

Had a customer with the same symptoms. Tire pressure was 25psi at each tire. Raised the tire pressure and her car went back to normal.

 

New tires doesn't mean proper pressure was put in

 

New tires mean they inflated it to door placard psi. Way to low for good gas mileage.

What kind of tires did you buy? Inflate them to 44 front and 40 rear and see if you can stand how hard it goes over bumps.

Then:

Best way to check if your Prius is having mpg problems is find a nice flat highway. No hills. Then with the car warmed up set the cruise control to 55 and then don't touch the brake or gas. Push the reset button on the consumption meter to zero out mpg. Drive 3-5 miles and the consumption meter should read at least 52 mpg.

 

You are assuming they are good, but this is not something that can be assumed. Always check. Get your own tire pressure gauge if you don't already have one.

Some shops are good about setting pressure, but some are very sloppy. And I have had mounting problems that resulted in serious leaks around rim beads on new tires. It was fixable, but it was up to me to discover the leak.

 

What we notice in winter the car heat is on which makes the engine run and we are always green on the HV battery bars. Today, now we are running A/C more and this drains the HV battery so now we have more purple bars and blue bars and the green bars are harder to come by.

 

All the above give sound advice, but having had new tyres fitted could you please check the pressures as above "for a reasonable ride I suggest 38psi front 36psi rear but you can go higher than this if your happy with the harder ride.

Next new tyres do not roll as easily as tyres that have been run for a couple of thousand miles, so this will make the drive system work harder, and may produce the effects you are getting.

Finally can you let us know what new tyres have been fitted, make, type, size, and as much other information off the side of the tyres.

All this information will help us help you.

John (Britprius)

 

Please do battery test and tire pressure in the morning when car hasn't been used for several hours.

 

Hi Ali,

Thanks for running the test. A couple of questions for you. Did you run the test after the Prius had sat overnight without being driven? Also, on the second part of the test (Ign On) you report a voltage below 12.0 volts. Did you have any excessive loads running ie: headlights, a/c fan blowing, etc?

Also, when you check the air pressure in your tires you should check them when they are cold. Again, let the Prius sit overnight. There are quite a few odd's and ends that can cause the problem you are looking at. The battery and the tires are usually the culprits, but there are a couple of other things that are easily fixed and often overlooked.

Ron

 

11.8 under load. Yep its time for replacement for sure. Soon it will throw up a quick red exclamation point upon start up
which means HELP! I'm getting ready to leave you stranded.

How many times in that battery's life have you had to jump start it?

 

Not so fast. I think you are judging by the traditional non-hybrid scale, but my Prii have tended to run lower voltage without problems. The low batteries that caused problems for others have been considerably lower than that.

Wait until we get the cold morning reading.

 

In case it is a low 12 volt battery, you want an AGM battery with external venting. Two that are sold in the US are:

Optima DS46B24R Optima battery direct fit replacement for Prius 2004 + & Plug-in Prius with Instructions


Exide AGM Car Battery (Group S46B24R)

 

As I suspected, your battery is getting weak. However, that is only part of the big picture. Check the air pressure and let us know what they read.

There is a survey you can fill out if you want to, however for now lets focus on the two items (battery and tires).

Here is the link to the survey. If you were to fill it out, that will give us more information to work with. FWIW, your 12 volt is definitely weak and probably will have to be replaced soon. Since you are in FL, you should be OK till winter, but it might go bad then. You really don't want to be in a situation where you have to jump start a Prius. One wrong move, and thousands of dollars of damage if you jump a Prius the wrong way. There is only one way and one shot. If you do it wrong, there is no easy and cheap fix to it.

Fuel economy complaints/queries? Please copy, paste & answer these questions, esp. if you're new | PriusChat

Anyway, let us know what the tire pressures are and fill out the survey if you have the time.

Ron

 

It does sound like you need a new 12 volt battery. Your new tires will add to the rolling resistance even if the pressures are correct so you may see an mpg impact. Did you get any brake work done when the tires were replaced?