Weird stuff happening? MPGs dropping? Test The Battery

thanks very useful to know. my mileage has been dropping, but i chalk it up to the weather mostly.

my radio presets have been lost a couple times in the last few weeks. might be the battery!
I wish the ECU would automatically throw a warning light if it detected a 12V battery issue.

 

I was lucky and got my car in to the dealer today. It turns out the inspection had run out, so there was another good reason to have it looked at.

Diagnostics showed everything is well. I think I'll pick up one of those small jump-start units just in case.

I checked my mileage today and I got 53.3 mpg @ 27F, on the way to the dealer (after a reset) so my mileage appears fine.

I'll dig out my voltmeter, locate that jump-start post, and if I feel adventurous, try going into Maintenance Mode.

Thanks to everyone for the advice.

Harry

 

I was told by a service person at the dealer that the red warning triangle I saw yesterday and again today when starting my Prius was a warning that the voltage on the 12-volt battery was low.

 

Does the 2010 have the same or similar diagnostic procedure?

 

Maintenance Mode is much more convenient. Exit Maintenance Mode by shutting off the car.

 

Bingo! Thanks!

 

Do you have to have navigation to enter the maintaince mode or can you do it with a pkg.#2?

 

Nope, don't need Nav, works fine without.

John

 

For all my prior cars, ICE cars. Whenever I had battery problems, I take it to a battery dealer and they check the battery, it mostly come back OK. But then my car keeps not starting and I have to tow it.

So now I just replace the battery whenever it stops starting the car reliably.

What I mean to say is, consider just replacing the battery. Then you don't have to carry the jump start thing around. You would save some money on the battery because you don't have to buy the jump start battery. Just my humble suggestion.

 

This needs to be sticky.

I would suggest the title to say "Weird stuff happening? MPGs dropping? Test the 12V battery (with instructions)"

 

So i tried this technique and found that my battery after 1 year is as follows:
Unload: 12.4V
Load: 12.1-12.2V
Charge/Start: 14.2 V

I don't think my decrease in mpg is due to the battery. Has anyone else experienced a decrease in mpg, about 10mpg, and fixed the problem yet found the cause?

 

FWIW, I find significant changes in MPG with the cold weather. When the weather is in the mid teens, it takes awhile for the engine to warm up, resulting in lower MPG. Yesterday, when I drove to work it was colder and overall efficiency was poor. In the ride home, it was just above freezing and mileage was excellent. You live in Anaheim, doubt you have cold weather like I have! Maybe some other environmental issue?

 

My battery was shot. I tried to start the car and every light on the dashboard started blinking. I got a jump and then proceeded to the dealer. I have a 2007 Prius so the battery was under warranty. My mileage had gone from 45 mpg to 35 mpg. After a new battery was installed my mileage has not improved. Any ideas/comments?

 

well i think this easy do rundown ( to a point of braking it ) small 12volt prius battery needs to be a recall where all 12volt battery's are replaced bt better one's
its seems to me this is really something that happens a lot but is not a big thing just a design fault to me.

 

Where do you live? Could the weather have anything to do with it? Could the dealer keep the car and go for an extended test drive to see if he can replicate the problem?

 

I live in Charleston WV. I have not noticed my mileage suffering in previous winters. I will weather the cold storm and if I don't see any imporvement in the Spring I will have dealer check into it.

Thanks

 

I read you posting regarding testing the 12V battery. I followed the instructions in the posting (thanks to jdenenberg). Fortunately, my battery passed the "test".

I am curious though; where did you or jdenenberg find the battery test? Also, how many more tests are available in the Prius and how can I learn of them? Incidentally, I have a 2006 Prius with package 7, if that's the one with fog lights, GPS, Bluetooth, and backup camera.

Thanks, in advance, for getting back to me.

Joe1987

 

This my first winter with the Gen II 2009 Touring-my MPG's has dropped from the low 40s to the high 30s. I just recently swapped the stock 195/55R16s to Nitrogen-filled Nokian WRG2 205/55R16s, which will cause a minor hit as well.

I noticed the warmer it gets the better my MPGs are-when it gets bone cold (0 to minus 15 F), fugheaboutit.