So I have had my Prius for a bit over two weeks now. This is not a "Why aren't I getting better MPG" question. And I have done several searches, but have not found the info I am looking for. For the first week and half or so I noticed that whenever I was gliding/coasting/braking or using only the electric motor the MFD would show a 99.9 MPG. At acceleration and lower speeds it would show on average 25-30 MPG. For the last 5 days or so, when I am gliding/coasting/braking the MFD doesn't always show 99.9 MPG. It seems to be really random, at times it shows 30, 65, 92,75 etc. More often than not it doesn't show 99.9 like it had the first couple of weeks. Sometimes I am regenerating power into the battery and neither ICE/Motor or showing arrows going towards the wheels and it will still show odd MPGs. It seems to have no rhyme or reason. There are also times when it shows the car is only being driven with the electric motor and it still shows random MPGs. At acceleration and very low speeds it typically is showing anywhere from 8-19 MPG, when previously I was only seeing 25-30s. I've also noticed that there are times when the energy monitor does not show any arrows from the ICE but it sounds like I am hearing it running. Is my display having issues? What are some hypothesis out there for an observation like this? I am sure it could be a number of issues, including newbie misunderstandings. Thanks for your thoughts.
when the engine is running (even if your foot is off the gas) it will show lower mpg's. if it is doing that more, your 12v might be weak.
12v is a little low. I ordered an optima and am picking it up tommorow. I read about the stages of the hybrid system and will review again for better understanding. Other opinions or info is certainly welcome.
This is completely normal. If you are not in S4, your engine will sometimes still be running but not charging or supplying pwr to the wheels. You will be in either S3a or S3b. To transition to S4 from this stage, you need to reduce speed to less than 7mph (stopped is best) for 7-10 seconds (until the engine stops running). This procedure is commonly referred to as an idle check. If after you do this and you are still seeing those readings, something could be wrong but, I doubt it. If you're not getting any warnings/codes and getting above 38mpg, there is no problem.
Thanks. Sounds like everything is normal. I guess I just wasn't as observant in the first 12 days or so. I do a lot of short trips so between that and the low ish 12v battery the batt is often at a low state of charge. Which would kind of make sense that the ICE is working over drive. I just picked up the optima today. Now gonna research how to change it and compare to what my mechanic will charge to change it. I'm not the biggest DIYer.
Climate control settings and requirements for heat are the other thing that will cause the engine to run. So to summarize, there are several things that will cause the engine to continue to run, even when not required for motive power. - Hybrid stages 1 or 3a - Requirement for climate control heat. - Requirement to charge very low SOC on traction battery. Unless the 12V battery was so low it was causing some kind of malfunction then it wont have have caused the issue.
Please don't pay someone to install your battery (unless its just like $10). It is such a simple job. We can help you if you want. I'm hoping you got the newer Optima that fits right in with no mods. If so, it is an extremely easy job. Keep in mind that some parts stores will install a battery bought from them for free. If you didn't buy it from them, you may ask them to help you anyway. If I was working, I would do it. If the guy or gal is bored, they just might do it.
I've read that it takes some people 30 minutes and some 3.5 hours. So I think what is easy for some might not be for others. Disassembling the air vent worries me a bit. If it were just like a normal battery it wouldn't concern me.
