Not getting the rated 45 MPG. Problem with batteries?

Age equals resistance in electrical stuff generally speaking The older it gets the harder the electricity flows whether it's corroded bus bars corroded nuts on the bus bars what have you worn out modules etc . All of these things add up to create the problem In a generation 3 EGR cleaning and maintenance can be a thing All of these things going south can equal bad mileage yours is extremely bad although the generation 3 is rated for 39 to 51 miles to the gallon depending upon what kind of driving is being done. My generation 3 gets about 45 47 somewhere right in there I've never seen 51 or 52 like a lot of people on this list. Rather than just looking at bad modules and whatever look at the overall health of the battery in like Dr Prius state of charge things like that all the individual blocks things like that one or two being low is bad with that kind of mileage you should have been out of the factory original battery a long time ago playing the whack-a-mole game with individual modules and what have you is very temporary at best. I put a $3,000 battery in one of my cars and mileage went from 39 right back up to 45 immediately like the next day.

 

i don't think the bms would work properly

 

I have no idea buddy I'm not an electrical engineer or anything like that You can do anything you want whether you'll get the desired results I have no clue I understand the expense and all that I also had a guy that I bought a battery from up in DC Fredericksburg Maryland area the hybrid doctor who has a shop that plays games with all these batteries He has a lot of expensive equipment and all of that I guess he could do Tesla batteries and all that He goes to all kinds of electric car shows and is really into the battery end of the game He built the battery for my generation 3 which is the same battery as a generation 2 minus it's different front end and it has been working for almost 2 years impeccably very happy for the $700 I paid. The 1500 that I paid for the brand new battery which is now right at a year and a half old almost two still doing well also maybe try it with a professionally built $700 rack of modules see how that does Make sure your EGR and all that stuff is not clogged up and that everything else is in pretty good condition and that should put you at least back to around 45 47 I would hope.

 

Brand new what do you mean by brand new Prius with a drop in mileage like that? How many miles are on the new Prius new to you Prius? I mean like a 2019 or something seriously?

 

A Toyota mechanic will tell you that 37mpg is within range or normal... Usually low tire pressure is the primary cause of bad MPG. And also your battery pack likely needs reconditioning and balancing, as well as the car in general could have a great number of things limiting your MPG because you have that many miles on it. Please let us know more about its maintenance history and we can likely give you more advice on how to get MPG higher.

 

Have you reviewed everything in this questionnaire?

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

It was meant for new drivers of new cars, so doesn't well cover old-car issues (e.g. aging batteries, dragging brake pads, etc.). But it has numerous points and issues to check before doing anything major to the car.

 

What is the new Prius that is faltered to this low level of mileage that you speak of You say new that means 2023 2021 a 2019 just trying to gauge what we're talking about here.

 

Well you're beating the dead horse if you're doing this to old batteries like in the 12-year-old plus range You're 2021 thing that's a generation 3 or similar generation 4 2ZZFXE so you should get about the same mileage as a generation 3 maybe a tad more I run the h a l e out of the air conditioning in my generation too It normally's getting around 47 it might get 45 in town with it 73° in the car pretty cold or less My air conditioner goes on in mid May and stays running until October maybe even parts of November and my gas mileage does not go down to anything like 35 36 none of that . But I guess if your batteries are beat to death possibly my generation 3 I have a persona it's only a 2013 a lowly older model it still gets 47 mi to the gallon My wife never turns the air conditioning off even runs it in the winter always 47 mi to the gallon it'll falter off of that maybe a mile or two because well she kind of drives like an idiot sometimes oh well.

 

Usually the primary cause of bad MPG is listening to bad advice on Internet forums.
This is a perfect example.

 

And I'm pretty sure that THIS is the reason:
"Old car, over 340k miles. Some battery cells are original. "

 

42 front 38 back....psi