My 2004 Prius has 102000 miles and it seems to be getting less MPG. I used to average around 43 and now I'm getting 38 or 39 MPG most of the time. Has anyone else experienced this? I'm wondering if the battery loses charge capacity as it ages.
Some people have reported that a failing starter battery (not the traction battery) has this effect. Does your Prius have the original battery?
Yes. I don't think I've changed the starter battery. It's been 6 years so I'll try replacing it and see if that helps.
If anything, my '04 is getting *better* MPG at 130K, esp. as this summer kicks in and on the new Michelin EnergySaver a/s tires. Finished a run to the Cape and back just today, showing just over 70 MPG and much of that was highway at 60+ mph. Traction pack is fine, as recently checked, and its 12V is still the yellowtop from elearnaid which I don't expect to poop out for a good couple more years. . _H*
Before you replace the battery check the voltage & report the readings. For the record, I expect your 6 year old battery to be weak but KNOW why you're swapping out a part, don't GUESS or HOPE that will solve your problem.
+1 What tires do you have now (size, make and model please) and what pressures do you keep them at? Perhaps you've changed them to something w/higher rolling resistance? Yes, the HV battery does lose capacity over time but government long term tests didn't show significant mileage changes, at least not on Gen Is. See http://priuschat.com/forums/gen-ii-...-miles-w-dropping-mpg-common.html#post1014257.
that's excellent H! any tips? we usually get low 60's on the way down and high 50's on the way back. factory tires and 55-65 mph. mostly 65. thanks!
Good point. I checked and it's 12.5 V cold and 13.75 when idling. So the battery seems to still be fairly good. Hmm. About a month ago I got new Michelin Energy Saver A/S P185/65R15 all at 35 psi. I was getting about this mileage with my previous tires and assumed they could be the problem. When the sidewall of one of them ripped I decided to replace the tires with new energy savers. If anything, the mileage is a little less than before.
The new tires must "break in" before they will yield good mileage. It's time for the spark plugs to be checked/replaced. Engine air filter ok? The Prius is good at not aging fast, but even it requires maintenance eventually.
Very late answer to bisco and anyone else curious: This may help, as I hadn't finished writing it at the time the topic came up... . _H*
Yes I am curious enough to start a new thread here: http://priuschat.com/forums/gen-ii-...y-mode-lower-speeds-50-55mph.html#post1139988 Please kindly reply questions asked there. Thanks!
I think you need to turn on the headlights and see it that 12.5 V imediately drops below 12 V. I new fully charged battery would be closer to 13.2 V with the car off.
