Suggestions To Lexus

[wstr75]

We live in a hilly area and our home is in a neighborhood at the top of a 800 ft. hill (we call it a mountain, but folks in Colorado would call it barely a hill). Every time I go into town, by the time I get to the bottom of the hill, the battery is maxed-out green and the brakes are no longer regenerating. Yet, try I can, the only times I can get the car to run on battery alone is either starting from flat or down hill locations. Even then, if there is the least bit of rise in the road, the ICE kicks in. So I'm primarily tooling around with a fully charged propulsion battery and running on ICE at slow speeds. If there were a way to force the car to stay in electric propulsion only mode, I'm sure I'd see 3 mpg better mileage in my home area. I've read where Electrical Engineers in Southern California have "tricked" their Prius into driving on battery longer than stock set-up. While I'm not of a mind to screw-around with my Lexus, it would be neat if Lexus offered a setting change that us owners could switch on and off much like the towing mode some trucks have.

On another note, it's too bad Lexus/Toyota did not put power resistors in series with the braking/regeneration circuit. When the battery goes green, the regeneration braking could continue but just throw away the juice in heat energy rather than wear on the brake pads. I know someone is going to say that the brake pads are dissapating heat energy, too. I guess using power resistors would add a bit more complication to an already complicated system. You could take this even further and put the power resistors in the coolant and use braking heat to help heat up the car in cold climates so as to reduce ICE operating time.

Hey you Lexus engineers reading these forums! Listen up, you hear?!

[wstr75]

Correction: 300 foot hill. Top elevation 1140 and bottom elevation 840. So the car goes green over a 300 foot total drop over a 1 mile run.

[skyfish400h]

...it would be neat if Lexus offered a setting change that us owners could switch on and off much like the towing mode some trucks have.

On another note, it's too bad Lexus/Toyota did not put power resistors in series with the braking/regeneration circuit. When the battery goes green, the regeneration braking could continue but just throw away the juice in heat energy rather than wear on the brake pads...

I am disappoined as well that there is not more user contol over the operation of the HSD system. Perhaps some hacker in the maintinance mode can figure some things out for us... hint, hint.

As for the power resistor idea, I can see two problems: One is the cost of adding onto the HSD system which you already mentioned, and the other is that brake pads and rotors are cheaper than the electric motors and HSD components. Putting extra work (and were) onto them just to throw the heat away would not be cost effective. Better to disipate the heat in the traditional way with eaisily replaceable (and relativly cheap) parts.

Capturing the heat is a good idea, but I doubt that the relatively small amount of heat generated (on an intermittant basis) would be very useful to the HSD system on the whole.

[wstr75]

...it would be neat if Lexus offered a setting change that us owners could switch on and off much like the towing mode some trucks have.

On another note, it's too bad Lexus/Toyota did not put power resistors in series with the braking/regeneration circuit. When the battery goes green, the regeneration braking could continue but just throw away the juice in heat energy rather than wear on the brake pads...

I am disappoined as well that there is not more user contol over the operation of the HSD system. Perhaps some hacker in the maintinance mode can figure some things out for us... hint, hint.

As for the power resistor idea, I can see two problems: One is the cost of adding onto the HSD system which you already mentioned, and the other is that brake pads and rotors are cheaper than the electric motors and HSD components. Putting extra work (and were) onto them just to throw the heat away would not be cost effective. Better to disipate the heat in the traditional way with eaisily replaceable (and relativly cheap) parts.

Capturing the heat is a good idea, but I doubt that the relatively small amount of heat generated (on an intermittant basis) would be very useful to the HSD system on the whole.

I agree with your observations. Brake pads are cheap. Tonight we drove through downtown Greensboro and were on the electric motors for about 2 miles (averaged 40 mpg for that 5 minute period!). The speeds were 0 - 20 mph and the road was flat. I guess 400h owners in Florida tooling around downtown areas rack-up outstanding gas mileage as the motor doesn't have to run long to get up to temp and the terrain is flat.

Say, those of us with AWD 400h with our front and rear electric motors/generators, do we get double the regeneration output during braking as a front wheel drive only versions?

[Rx330driver]

i see another problem with the whole being able to switch from gas to elec manually. Lets say you do leave it on the electric motor, and you just gas it...it would burn out the motor. Lets be realistic, that motor only churns out so much power to move such a heavy car. you might as well add pedals to all the passenger seats to help out the electric motor.

[RX400h]

I've read where Electrical Engineers in Southern California have "tricked" their Prius into driving on battery longer than stock set-up. While I'm not of a mind to screw-around with my Lexus, it would be neat if Lexus offered a setting change that us owners could switch on and off much like the towing mode some trucks have.

Unfortunately, this could significantly reduce the life of your batteries. Toyota knows that the batteries that are used (NMH), like the standard lead-acid battery, last longest when they are not discharged past an ideal percentage range of full. Even marine-type (deep-discharge) batteries like the Optima Yellowtop rarely live past three years, compared to 5 years for a standard auto battery.

Maybe if a complete set of batteries for a hybrid could be purchased for $300, you wouldn't mind replacing them every 4 years of deep-discharging, but this is not the case. I'll keep my 25 MPG and a battery lifespan of 10 years, thank you.

[wwest]

I've read where Electrical Engineers in Southern California have "tricked" their Prius into driving on battery longer than stock set-up. While I'm not of a mind to screw-around with my Lexus, it would be neat if Lexus offered a setting change that us owners could switch on and off much like the towing mode some trucks have.

Unfortunately, this could significantly reduce the life of your batteries. Toyota knows that the batteries that are used (NMH), like the standard lead-acid battery, last longest when they are not discharged past an ideal percentage range of full. Even marine-type (deep-discharge) batteries like the Optima Yellowtop rarely live past three years, compared to 5 years for a standard auto battery.

Maybe if a complete set of batteries for a hybrid could be purchased for $300, you wouldn't mind replacing them every 4 years of deep-discharging, but this is not the case. I'll keep my 25 MPG and a battery lifespan of 10 years, thank you.

Anyone else considering a tow-along genset?