Electric Motor after 42MPH?
 

I have a 2006 Toyota Highlander Hybrid base model. No 4wd.

Does the electric motor disengage after 42MPH or what. And passing on the Interstate at about 60-70 if you floor it will the electric engine still be able to assist or will it be the V6 engine only/

Re: Electric Motor after 42MPH?
 

There is a maximum speed that HSD vehicles can go using ONLY the electric motor after which point the gas engine needs to run. The electric motors can ASSIST the gas engine at any speed AFAIK.

Re: Electric Motor after 42MPH?
 

40 MPH is the maximum speed that the electric motors can run without the engine also running. Also,when coasting to a stop without your foot on the accelerator, the engine will not shut down until your speed is below 40 MPH.

Re: Electric Motor after 42MPH?
 

What?? I can't go more than 15-20 mph without the ICE kicking in. I'd love to keep the engine from starting.

Re: Electric Motor after 42MPH?
 

Accelerating up to 40 MPH under electric motor power alone is very difficult and it does not use the battery energy to advantage. The ICE is programmed to operate under acceleration conditions in combination with the electric motors. If you accelerate excruciatingly slow you can probably reach above 30 mph if all conditions are just right. The engine is most efficient under a load and moderate acceleration is one of the efficient modes for the ICE. High speed driving with the consequential wind resistance and driving up hill are other efficient modes for the ICE.

If you travel 45 mph and decelerate to just below 40 MPH with your foot off the accelerator, the engine will stop if the vehicle is warmed up and it is not unduly cold outside. You can now get the vehicle to run on electric for a short duration only as long as the terrain is flat - no hills or even a slight incline -and you do not try to accelerate.

Re: Electric Motor after 42MPH?
 

I got to 41 MPH on just electric the other day and traffic was pissed off.

Re: Electric Motor after 42MPH?
 

You really don't want to use the battery pack only for acceleration. My best results are usually when driving in 35-45 mph zones, using moderate acceleration and then cruising/coasting mainly on battery power.

lakedude is correct. From my experience the engine is always running on the highway, but the battery pack will sometimes kick on and provide a little boost.

Re: Electric Motor after 42MPH?
 

I'm new here. Can you explain why we would not want to accelerate using only battery power? Assuming that we won't be shot, wouldn't it be a great way to increase mileage?

As a further consideration, because I read that the rx 400h batteries discharge when parked overnight, I try to use every last bit of battery power for my urban driving before parking for the night since the engine usually starts up in the morning regardless of how well charged the battery was the night before.

Thanks.

Re: Electric Motor after 42MPH?
 

The battery packs cannot provide adequate power alone.

Re: Electric Motor after 42MPH?
 

[quote=mjcmjc;119344]I'm new here. Can you explain why we would not want to accelerate using only battery power? Assuming that we won't be shot, wouldn't it be a great way to increase mileage? quote]

Acceleration usually requires more power than driving at a constant speed. The engine is most efficient at converting fuel into mechanical energy when operating under a heavier load. Since the engine will run frequently to keep the battery charged anyway, it’s best to allow it to run when the power demand is greatest. Why discharge the battery with painfully slow battery-fueled acceleration only to have the engine kick-in for a battery recharge while you are cruising along at 35-40 mph? It’s usually more efficient to accelerate under engine power and cruise under battery power.

Particular driving situations may favor battery power acceleration such as accelerating a short distance to then stop again, or accelerating at the beginning of a long downhill run where regenerative breaking will be used.

As you noted, using up some battery charge just before shutting down is a reasonable way to maximize your mileage if your driving route allows it. I have a 2 mile long, 35 mph run just before the parking lot at the office. During milder temperatures, I run on battery power for just about that entire distance. The battery charge will drop a few bars before I shut down. During engine warm-up on the next drive cycle, the engine will charge the battery which places a greater load on the engine making it more efficient and also warming it up faster.

Re: Electric Motor after 42MPH?
 

Thanks, Don R, for the explanation. It sounds like I was trying to do a little too much and should leave much of the MPG increase specifics to the engineers who programmed the car. In other words, just having a light foot, looking ahead, and driving conservatively should do a lot. Next progression would be pulse and glide?

Re: Electric Motor after 42MPH?
 

I've been playing with electric-only at low speeds... in my 400h, it's useless at anything outside of my cul-de-sac. I have about 70% full battery, drove maybe 1 mile at electric only, and in addition to it taking 20 seconds to hit 20 mph, it nearly emptied the battery. This doesn't seem efficient to me considering how long it takes to recharge that much battery power.

Re: Electric Motor after 42MPH?
 

You're right - it's not at all efficient used that way, and wasn't designed to be due to limited battery capacity. It's a big mistake trying to run in EV mode as much as possible and depleting your battery quickly unless you have predictable downhill braking runs to regenerate. Without this, the ICE has to recharge the traction battey at an efficiency of probably around 20% (ICE efficiency of about 30% times mechanical generator efficiency of about 70%).

Accelerating modestly with the ICE to just over target speed and then gliding in EV mode is much more efficient, with brief computer-determined motor boosts - using both in their most efficient modes. Anytime you try to accelerate in EV mode is just a killer of the traction battery as you've found out.

The only free lunch in hybrids is in braking regen mode, which is what they are all about, allowing accessories to keep running independant of the ICE. Don't waste this on acceleration trying to do what the ICE does much better, and more efficiently.

Things WILL change to what you wish you had now in a few years when battery capacity grows by quantum leaps and every car is a plug-in with a much smaller ICE.

Pete

Re: Electric Motor after 42MPH?
 

My good EV runs are conviently broken up by either an occational hill or higher speed areas. Using the battery on the flats, I usually run if fairly dry, but this I get to an area where ICE is pretty much necessary & I get a recharge, usually just in time to start me next <=40mph flat.

I'm actually seeing speeds of between 42/44 before ICE is mandatory, but the closer I get to this point the less chance of even holding speed on electric alone.