My house is at a lower elevation. The last 2 miles of my commute is a very gentle down slope back to the house. Most of the time I can run in stealth and cover the last miles. This boosts the mileage but also result in a low HV battery when I get back to the house, usually about 3 or 2 bars. Car is driven daily, or at least the day after, no long term storage. Any harm in parking the car with a low HV battery?
i don't think so. i used to do that in my gen II. i don't think there are any warnings in the owners manual. but i was told even tho my mpg's went up at the end of the day, it took more gas to restore the battery the next day and overall a net loss. i always thight the warm up the next morning recharged the battery for free, but maybe not?
What I find on a cold start up is, the engine is running, but the arrows are still coming from the HV battery, as if the engine is weak and not putting out much power. I usually glide out of the subdivision as gently as possible, resulting in little or no eletricity use. Then when it comes time to go up that gentle slope I came down the night before, the ICE runs in the upper range of the ECO bar, battery gets charged to 4-5 bars by the time I get to the flats. I pay for whatever free miles I get. I just wonder if the battery likes to be in a low charge state. What is the ideal SoC for storing NiMHs?
someone smarter than me will have to answer that, but i've never heard it mentioned before. even the new pip lions don't mention short term charge storage levels, just long term.
I don't think the battery cares. It is nice to run that last mile on battery & goose the numbers. In the morning I leave whatever I can off until the highway as the ICE is running to warm & charge the battery anyway.
The only limit to "storage state of charge" is how long it will be stored and whether the battery will self-discharge far enough so as not to be able to start the ICE when you eventually do power up. You can leave a NiMH cell (or bunch of them as in a battery) in any charge state you like for as long as you like. With the only provision being what I stated above. Now, going by the indicator in the Prius, there is not a huge difference in charge state from full bars to 1 bar. It's a "compressed scale". 80% at full bars and 40% at one bar. The system is designed to be ok with storage starting at 30-40% charge, and sitting for three months or more, and still starting. More information you probably don't want. Running on battery only is inefficient. It's about 50% efficient compared to running on the ICE only. This is because of the losses of charging and discharging the battery as well as the losses in the electric motors and inverter. The Prius is NOT an electric car. It's an electrically assisted gasoline powered car. Including the PIP. The PIP just has some "supplemental" electric power. It still can't go far on electric only power.
Yes I am aware of the conversion losses. However, if the terrain is such that it require very little power to operate. wouldn't it be more efficent to let stealth take over (not forcing into EV mode), since ICE does not operate efficently at low power output?
I drive Pearl S and used to drive Pearl about 5 blocks on residential streets at lower speeds to my garage and usually on electric only, but not using the EV switch. As I said, it does no harm. It -may- lower your mileage average a bit, though I doubt you would be able to tell as it would have such a small effect. It -is not- "more efficient" to do so. It just gives me a few nice low bars on the graph. Hyper-milers get their extremely high mileage numbers by NOT allowing EV mode. Their drive is the most efficient you can get, but not the most practical.
I would love a down slope to end of trip. I would put it in neutral which shuts off engine and regen & use that glide to clean the brakes. A daily cleaning of the rotors will really help.
I can see where using the ICE to charge the battery, then driving in EV mode may be less efficient. However, when the battery is charged by braking, especially that long slow brake to the stop light or down a hill, that energy does not use gas. If you never use the EV mode you seem to be throwing away that free energy.
Regen energy that is stored in the traction battery is only wasted if it results in a traction battery with greater than about 70% charge. At that point the car will drain it at all costs, sometimes just spinning the engine. Otherwise the energy is used the next time you need it (starting the engine, boosting the car from a stop, accelerating, etc.). Generating energy with the engine and storing it in the traction battery, then using that energy from the traction battery is about 50% as efficient as just using the energy from the engine directly. As an aside, the engine is about 35% efficient at converting energy from gasoline to propulsion. About 10% better than "normal" cars. Do keep in mind the regeneration energy was originally produced by the engine, even if it comes from a coast down a hill (you had to drive up the hill originally). Now if it was going to be wasted to heat by the brakes, then you are -recovering- energy that would be wasted. A minor difference, but an important one. It's -part- of what makes the Prius so efficient. A small part, but part anyway.
I find "the car will drain it at all costs" very confusing. I don't see how the engine can drain the battery. To use the energy in the battery the spinning engine must do some work. The wheels driving the car by way of the electric motor can do that but not the engine. Consider that you never see arrows pointing from the battery to the engine which would indicate the engine is using energy from the battery. The car can indeed drain energy from the battery as the arrows indicate as in the power mode. Yes, that makes sense. That's why mileage experts like the Power mode. Since I've already used whatever energy is necessary to get up the hill, the energy added to the battery while going down hill and then used in the EV mode is basically free. Using that energy to drive 1/2 mile is minor but definitely in the right direction.
no harm; your car's BMS will handle it. if the last two miles is downhill AND residential, try coasting it in neutral. granted might not be able to keep the speed up but I have been surprised at how well i could maintain speed (especially in the 20-30 mph range) on even the slightest of slopes
