Traction battery too large

The traction battery is basicaly the same KWh than the non PiP (PHEV) version.

 

Maybe they are being a bit more protective of the Li-ion battery until they get more experience/history. Its really bad to discharge Li-ion too deep, more so than NiMH.

 

***NOTE*** This only applies to pre-production (and retrofitted) PiP's:

Stealth in EV won't deplete the traction battery. Think of the EV batteries as a slow charge of the traction battery. That's what they do best. The traction battery is meant for the "gimme power now!" situations. If you floor it, brake, floor it, brake, etc that is coming from the traction battery. When you do that with NiMh it is less bad then if you do it with Lithium. So the power fluctuations are taken care of the traction whereas the continuous power comes from the EV batteries.

Drive like everyone else for a bit and race to the next line of stopped cars at the red light ahead, and you will see your traction battery go up/down.

 

Another does of PiP naivety from me, but there are both Li-ion and NiMH batteries (other than the 12 volt) in a PiP?

 

No.. just a 12v + Li-ion.. see the discussion here
Plug-in # of batteries | PriusChat

 

I am a bit confused. Is this thread specifically discussing the pre-production PiP, which had separate EV and HV batteries? In the production PiP, there is just one big LiIon battery for EV and HV, and a 12v battery for accessories. The distinction between the HV and EV battery being only in the programming and user interface.

 

no, confusion was added after the op. start at the top, is the traction battery too large? this is a false question because there is only one battery besides the 12v. op is questioning the amount of juice alloted by the computer after ev runs out.
my opinion is toyota did it just right.

 

I think the OP's use of terminology is making the question confusing. There is one traction battery whose full range is used in EV mode and a limited range is used in HV mode. The title should be "HV battery range is too large" and the original post should be (with changes in bold):

While I do feel it is difficult to deplete the HV battery range, it's not clear to me that the range is too large. Rather, I feel that the engine kicks in too easily in HV mode, causing the HV battery range to be kept in a small section of the HV battery range rather than varying across the entire HV battery range. I'm use to what seems like wider range from my previous Gen II. Perhaps other owners could provide Gen II vs Gen III and Gen III vs Plug-in comparisons.

 

Of course it is difficult to deplete the traction battery in HV. The car is designed to prevent that which would be very bad for the traction battery as drinnovatin correctly said. If the car is working properly the traction battery will never be depleted in HV.

It seems like the descriptions are of the HV function AFTER the EV range is used up. Most of my HV is driven with at least some EV and if possible a lot of EV range remaining. Then there is LOTS of EV use during HV (which does not count in the EV to HV ratio) with the result that HV mpg is remarkable AND EV range is diminished only little. Sometimes it is even extended. It is a whole different world of performance. I have seen individual trips as high as 180 mpg and as low as 70 mpg. It all depends on trip length, speed driven and the amount of EV range remaining.
The learning curve with this car is LONG.

If I know a trip is going to need HV I always start with HV and end with EV. I keep my overall mpg average above 100 that way with round trips of as high as 40 miles and an EV to HV ratio of 43% to 57%.

 

Scan gauge shows EV range as SoC 25-85%. Around 25% the car will drop into HV mode. I've noticed the car will let the SoC drop into the 24% range on occasion and milk that last 1/4 mile range of EV. I have been manually switching to HV mode once the car drops to 25-26% SoC just because it is so difficult to get EV range once it is depleted.

 

According to my scangauge, the car switches from EV to HV mode at 23.1% SOC. It won't allow you to switch back to EV mode until SOC hits 28.1%. Once you hit about 1.5 miles of EV range (I don't remember the specific SOC, I think it was somewhere around 32% SOC), it automatically switches back to EV mode.

 

In the Gen II and Gen III, it was possible to get the traction battery down to 1 or 2 battery bars, indicating that you had nearly depleted the usable section of the traction battery. There was always plenty of juice left in the battery, we just couldn't get at it. The car always made sure it had enough reserve left. Going up certain hills in my area in my Gen II, I would see the battery get down to 2 or 3 bars on a regular basis, and then get back up to about 6 bars. It wasn't uncommon sometimes for it to hit 1 bar for a short period of time, but it always got back up to 6 bars in a short period of time.

However, under the same circumstances with the Plug-in, starting out with no EV range at all, I've never been able to get it to go below 4 bars, and to do that required some effort. It normally just sits at 6 bars most of the time. It does seem as though the usable HV portion of the battery is a bit bigger than my Gen II. This might be due to the differences between the Gen II and Gen III, but a Gen III owner would need to chime in here.

My feeling is that the OP thinks that due to the propensity of the HV portion of the battery to remain around 6 bars indicates that the HV portion of the battery was sized a little too large. Perhaps some of that "excess" capacity could be given to the EV portion of the battery, allowing a slightly increased EV range, but still allowing normal HV operation.

 

The problem is not with the size of the traction battery. The problem is with the bar system of reporting the remaining charge.

Toyota engineers got it right.

 

Good explanation, Matches my experience exactly. Almost never see a decrease in HV battery bars without a concerted effort, whereas my 2006 routinely went to 1 or 2 bars.

 

just 1 o

Stop & go gridlock (especially on an uphill grade ) driving - at night, running high level of AC (ie, high electric consumption) would drain the Gen II & III traction packs to the point where the little displays show completely empty - not just 1 or 2 bars . . . . but as you mentioned - not empty in reality - but displaying empty. Toyota engineering, along with their industrial psychologists were aware of how unnerving "empty" auto readout can be. The designers got it right. This ain't their 1st hay ride.

.

 

In the 7 years I owned my Gen II, I never ever saw the battery indicator be completely empty, even afer a long drive up to Lake Tahoe. I'd get down to 1 bar, but that was it. Even when I ran out of gas and pushed the car as far as I could on battery, it always kept one battery bar visible. Rather than let me drain that last bar, the car bascially stopped going forward and "insisted" I get some gas.

 

getting 72 mpg's today in hv with a/c on and a 72 mile trip, i would say there's a little more juice in the hv portion of the battery and well worth the decisions toyota made.