Traction Battery Discharge in HEV Mode

It's not really anything to manage. I plug mine in most of the time when I get home. If you look at Gokhan's graphic, the ECU will not charge the traction battery more than it needs to. Mine always shows 40 miles of EV range when I leave the house. I drive it in EV mode (the default) when driving locally. On my monthly 1000 mile sojourns I use EV mode for the first 20 to 30 miles, then switch to HEV mode. The EV "miles remaining" almost never drops while driving through California's central valley and surrounding mountains. I take that back. When I forget to take it out of EV mode the charge drops.

The car does not deliberately try to replenish the traction battery energy when driving. It USES the traction battery to supplement the power available from the ICE and to store left over energy when the ICE does not have a perfect match to the energy demands of the terrain.

Last I heard, using regenerative braking is better than just heating up the brake pads, but it recovers a very, very small amount of energy when compared to the amount of energy needed to accelerate the mass of a 3500 lb car from zero to 60 MPH.

 

You have never owned one, and you keep posting without hardly knowing about Gen 4 and Gen 5.

That three-day statement by you is blatantly made up and false. There is no such mention.

Why do you think Toyota has charging schedule and made this statement in the owner's manual (page 113)?

■Capacity reduction of the
hybrid battery (traction battery)

The capacity of the hybrid battery
(traction battery) will decline gradually
when the hybrid battery (traction
battery) is in use. The rate at which
it declines will differ in accordance
with environmental conditions and
the way in which the vehicle is used.
Observing the following can help
suppress battery capacity decline.

●Avoid parking the vehicle in areas
with a high temperature under
direct sunlight when the hybrid
battery (traction battery) is fully
charged.

●Avoid accelerating and decelerating
frequently and suddenly when
EV driving.

●Avoid frequent driving near the top
speed for EV driving. (P.79)

●Leave a low level of charge in the
hybrid battery (traction battery)
when leaving the vehicle undriven
for a long period of time.
After confirming that EV mode or
AUTO EV/HV mode has switched
to HV mode, turn the power switch
off.

●Use the charging schedule function
as much as possible in order
to fully charge the hybrid battery
(traction battery) immediately
before starting off. (P.123)

Also, if the hybrid battery (traction
battery) capacity reduces, the distance
that can be driven in EV mode
or AUTO EV/HV mode decreases.
However, vehicle performance does
not significantly become worse.

 

Well they took away the "finish charge by X time" thing from Gen 5 so not sure how you really do the last point unless you're getting up at 2am to get only 30% on the battery to top it off when you last parked it at 70.

Or... just don't charge it when you think you won't be driving for a few days or enough to use much of the battery if its already at 90%

 

I'm not sure how one would parse the phrase "Capacity reduction of the hybrid battery (traction battery)" in English. It appears to be an incomplete sentence.

Is it a section of cautions about practices that reduce the EV range? Note that reducing EV range ? I note that a Li-Ion battery will lose several percent of it's charge right after charging. Some lithium batteries will lose more than others. So to prevent lose of range from internal resistance it would make sense to fully charge the hybrid battery (traction battery) immediately before starting off. As Zeromus noted, we don't have direct control over the exact charge level of the battery at any particular point in time.

It appears that the section is meant to provide instructions for practices to avoid in order to get better mileage when running on EV. It does not appear to be addressing battery degradation over the battery's lifetime. It appears more likely that it's telling us that rapid acceleration mixed with heavy braking will waste energy. And furthermore that a hot, fully charged battery is less likely to absorb the energy from braking without wasting some of that energy as heat.

As a side note, there's a conflict between "just in time charging" and the Time Of Use EV billing plan. If I charge just before leaving the house, I will be charged over 54 cents per kWh by PG&E, our local power company. It's only 34 cents per kWh at midnight.

 

Where I live, the ultra low overnight rate is what is basically intended for EVs. It only runs from 1am to 6am or something like that, and it is a super low rate of like, 3 or 4 canadian cents per kWh. But the tradeoff is higher rates during peak times from 9am-12 and 5-8pm. And the *high* rates are 30some cents. It works great for people with higher capacity batteries and level 2 charging where they can be fully charged over the course of 5 to 6 hours. For me, the regular TOU plan where the peak rate is 20 odd cents and off peak starts at 7pm for 7 canadian cents per kWh is a way better deal. The spread between hydro and gas is way bigger here. Our elec is way cheaper and gas a fair amount more expensive. So savings are much more easily realized.

 

Geez, that is steep, more than what some charging stations would charge. Where I live, I pay a flat 6 cents per kWh above the minimum service charge of $35.