EV mode not engaging and rear battery fan always on

Keep us posted...and does the Gen 4 Model Two (your model, right?) have NiMH battery or Li-Ion? I know my Three Touring has the new Li-Ion, and I haven't heard a peep from my vent fan in almost a year. Not that it makes a difference in your case, but would be interested to know. And you never mentioned your State of Charge (SOC) during this incident. I wouldn't worry too much about whether the EV light is on or not. There's way too many parameters involved to deduce anything reliable about performance and EV light. But your reduced MPG is a sign of something. And the fan, of course.

 

state of charge.

 

It's the level of charge in your traction battery. There is a graphic depiction, looks like a cylinder with a series of bars, maybe 10 in all, that light up from bottom to top and show the level of charge of the big battery. Should rarely get to the top, unless you are coasting down a long descent, but never to the bottom either. System management keeps it somewhere in the middle either through regeneration or ICE assist.

 

In the US Gen 4 Trims One & Two is NiMH. Trim Two Eco & higher are Li-Ion.
The Trim One was recently released to the public.

 

5-7 is about normal SOC for most running:


3 or less will generally bring the ICE into play to recharge to at least 4 bars. I've only seen 8 twice, on a steep downhill section.

I've got NiMH battery, but have never heard the fan in almost 12 months of ownership, so I'd get the dealer to check it. Hopefully they will put it on their scanner and look for any extraneous codes in the history.

 

Just a thought, have you considered using the air-conditioning on normal, or even fast to see if that affects things? You change it by pressing the Auto lozenge/button on the centre console and it cycle through the 3 states. Not sure it will help you, but we never know with some of the spurious anomalies the Prius throw out from time to time. Good luck anyway.

 

Just had this same issue... EV will not engage and battery fan on high. Just shy of 10k miles on 2016 Prius 2. 10k service a week ago. Made a short trip to the store and was in heavy rain on trip home. Outdoor temp went from 91 to 75. Went out a couple hours later and the battery fan was roaring! Shut down and restarted twice. Finally got home and parked it. Did run on battery backing into drive. Worried! Yes, I always have AC on Auto.

P01M ?

 

Try turning the Climate Control OFF, shut down then try again.
Also, check that you haven't got anything on the back floor which could be blocking either of the under seat vents.
Mine has a mind of its own sometimes, where there seems to be no good reason why it won't go into EV, but next time I try it's fine again. I've never heard the fan - but it could be my hearing.

 

60 mile shopping trip this morning and all seems well. Am more aware of the battery fan now. Only thing in the back seat is the owners manual, under drivers seat, and that has been there for 9k miles.

P01M ?

 

I believe there is a climate control vent under the front seats providing air to the rear seat passengers and the traction battery. Is the manual blocking that vent? The traction battery fan is on the passenger side too, assuming you have a left hand drive Prius. Your profile does not show your country or state.

 

I think it may have some sort of battery cycling mode that kicks in sometimes, where it occasionally runs the charge up to a certain level before using it.

 

Sometimes it does it's own thing - always seems to sort itself out in a few minutes driving. The computer algorithms would undoubtedly process many other "vital signs" which us mere mortals don't comprehend.

 

Floor vents are not active when AC is blowing from the dash vents. LH drive and the manual is under the LH seat. Also have had issues with the auto heat cool not detecting passengers in RH front seat or either back seat. Vents under seats for heat to back seat not air for main battery.

P01M ?

 

There is no rear seat detect. There is an HVAC switch to control that.

 

On this setting - - it blows out the floor vents as well as dash vents. In hot weather, with A/C on, it will be cold air on your feet and face. Turn S-FLOW to OFF and it will also blow through the rear floor vents as well (or have a rear passenger).

 

See manual page 519, S-Flow mode. In automatic mode, when the rear seat doors are opened or closed, S-Flow mode will not operate...

P01M ?

 

That may be so, but if you wish to, you can override that using the buttons to get it back to his YOU want it.

 

In the continuing saga, my SOC after parking overnight is one bar from the top. Off we go at a conservative acceleration and speed and within 1/2 mile the SOC drops to two bars and stays that way for several more miles with the ICE running before slowly regaining stored charge. This since the episode with the cooling fan. Gas mileage seems Ok. Discussion with the dealer revealed nothing like this ever reported and their reluctance to invest time Toyota will not pay for. Yes, all vents clean. There was mention of several problems caused by rodents... For now will keep an eye on things.

P01M ?