Prius (Disuse) Discharging Issues

<div class='quotetop'>QUOTE(ncc74656m @ Feb 7 2007, 06:59 PM) [snapback]386685[/snapback]</div>

No offense, but a Corolla isn't exactly overpowered, either. What, exactly, will you be calling upon your Prius to do?

<div class='quotetop'>QUOTE(ncc74656m @ Feb 7 2007, 06:59 PM) [snapback]386685[/snapback]</div>

Prius mileage is good 'till you get to around 55mph or so, then aero drag begins to have a greater effect. I think you can count on around 40mpg no matter how you drive the car. Winter temps can lower mileage, though. My last car was a '97 Porsche 911; I enjoy clipping the apexes in curves as much as the next person and average about 45mpg.

<div class='quotetop'>QUOTE(ncc74656m @ Feb 7 2007, 06:59 PM) [snapback]386685[/snapback]</div>

Search the site for more from folks who know lots more about this than I. Basically, if your car has the smart key system, you'd do well to turn it off using the button under the steering wheel. Otherwise, you might drain the 12v battery. Other than that, two weeks is no problem. As far as the HV battery, I don't think there are drain down issues with it; certainly not at two weeks. Again, use the search function; it works pretty well.


<div class='quotetop'>QUOTE(ncc74656m @ Feb 7 2007, 06:59 PM) [snapback]386685[/snapback]</div>

Normal driving will *never* do this to the car, and you can indeed coax it into all electric operation of you're really nice to it. But, if you install the EV switch, you can go all electric for a longer, if still LIMITED distance. Thing is, it can take the HV battery outside of its 'safe' range of charge (which can *drastically* reduce its life) so you'll be on your own if you undertake this mod.

Do more research on the capabilites and limitations of the car. Performance-wise it's got enough power (certainly if you're coming out of a Corolla!) and with the TRD suspension pieces, it's faster than the average motorist would expect. Top speed is 104-ish mph, though, so if you're into high speed blasts, this is *not* the car for you.

 

Well, as far as fuel economy, that would depend on how hard you push the car, and the ambient temps. At the worst extreme - a lead foot and under 0 F - you might only see high 30's. Otherwise with a bit of moderation and a nice day, 45-55 entirely reasonable.

As far as the effect on the battery letting the Prius sit, there are actually two separate batteries: a very tiny 12 vdc (Think motorcycle battery) that powers the computers, headlights, radio, wipers, HVAC blower, brake boost pump, and coolant transfer pumps; and, the nominal 208 vdc NiMH "traction" battery that starts the gasoline motor, and assists in driving the car, along with accepting charge during regenerative braking.

When the Prius is powered down, the HV relay is open, so the NiMH battery is electrically isolated from the rest of the car. In theory the NiMH pack can sit a long time, 3-6 months with some reports of even 12 months with no ill effect.

However the tiny 12 vdc auxilary battery is another matter. Depending on how the car is used, some folks have had issues with "normal" driving. I was one of them: my city driving cycle in cold winter, headlights on, electric defrost on, no more than 30-45 minutes on at any one time, and the battery started to become weak after the first winter.

If the car has the optional Smart Key System, this can be easily disabled to minimise power drain. In theory the car should be able to sit 2 weeks without problems. More than a handful have reported dead batteries, so YMMV.

I finally cured my battery problem by using a VDC Electronics Battery Minder, which will keep a float charge on a battery and use a special high frequency pulse to desulfate and condition the battery. I use the Battery Minder whenever I'm parked at the condo, or at my hobby farm.

http://www.vdcelectronics.com/batteryminder_12117.htm

Note I got the previous model at an auction for about 1/3 what they're asking for a new one. It has almost exactly the same features as the new one, not sure if it's worth $70.

Here are some pictures

 

My two cents, which will sound a lot like an echo at this point:

The performance is well above what you'd expect. In fact it's better than my last car that had a V6. I wouldn't say top-end is the same, but how many of us get going that fast anyway? I've played tag with a Honda Civic Si on the highway one night and easily did over 80MPH with great acceleration. In fact from a stoplight I out accelerated it. (I'm guessing because of the smoothness of the transmission.) So I have to say the performance of the Prius is pretty darn good.

However when you push it over 55MPH the gas milage does really start to drop. 65 is still reasonable. 80 is just awful. (And by awful I mean mid 30s. So take 'awful' with a grain of salt when compared to other cars.)

Winter gas milage also blows compared to moderate temperatures. The engine is just cooled too much but keeps trying to run to keep warm. Stuff some cheap pipe insulation into the front grill to help for long trips. Install an engine block heater to help for short trips. Be more creative if you feel like it.

The Prius also isn't like other cars that switch a lot between electric and gas. It's a true hybrid synergy drive. Most often both electric and gas are running side by side helping each other out and maximizing your MPG. Only when you're going pretty slow does the electric-only mode kick in, and even then not always. And unless you aftermarket mod your Prius, there's no manual way to switch back and forth.

And the battery drain in the 12V is mostly caused by the smartkey. Turn that off and you can easily go two weeks without use. The HV battery can go much longer without use. So just shop and/or use carefully. If you buy one with a smartkey, turn it off while you're away. And maybe get a simple jump kit. Since the only drain on the 12V battery to 'start' the car is to switch on the computer and the HV battery, it's super-simple to jump. Any crappy portable kit will do on Prius. I woudn't bet on it, but I wonder if you could even start a Prius with a simple 9V battery. :lol:

As for what kind of gas milage you personally could expect to get? That's a hard call. You'll definately get less than my typical 56MPG. I'd say you'll be averaging in the low 40s if you're doing 80MPH down the highway. Stick to the speed limit (which is always good advice in general) and you'll probably be doing in the 50s.

I'm not entirely sold on the stock tires though. So far I'm not impressed with their traction, and if I didn't know better I'd say they have a random wander factor that makes sure you have to keep your hand on the wheel. I can't wait to burn through them and buy new ones. :lol:

 

One little thing to note when you are doing your test drive that confuses a lot of new Prius drivers: ignore the sounds. Just mash the accelerator and the car will go. There are no gear-shift kicks to tell you you're in the next gear. The Internal Combustion Engine (ICE) is controlled by the computer, which also controls the electric motors. You may hear the ICE revving fast and it may seem like the "clutch" is slipping since your perception of speed isn't getting the usual cues. Ignore the sounds! Everything is functioning properly. You may be cruising at 60 mph and the ICE cuts off. Don't worry. You may pull up to a stop signs and it feels like the ICE stalls, giving the car a little shake, and then dies. Perfectly normal, just step on the accelerator when it's time to go and you will.

When you are cruising and take your foot off the accelerator, it will feel like automatic transmission drag is slowing your speed. This is fake, built in to not freak out drivers unfamiliar with a Prius. When you put your foot on the brake, you are telling the computer you want to slow down, so it increases regenerative braking (turning forward motion into electricity to store in the High Voltage battery) based on how hard you push the pedal. Unless it's a full-on panic stop, the friction brakes won't come on until about 7 mph. Regen braking doesn't sound like "normal" braking, so ignore the sounds.

The Prius is the smartest car on the road, and completely different from any other car you've ever driven. The Multi Function Display can be very distracting at first. Turn it off and just drive. See if you can rent a Prius for a weekend, it's hard to get a good feel for the car with just a short test drive.

I hope you decide to buy one. They are fabulous!

 

It sounds like your trips are long and far which will be good since you'll be doing less warm up periods. Traffic on FDR and West Side Highway are very good for Prius during non-rush hours. If you go 50 mph, you can get 60 MPG if Prius is fully warmed up.

If you cross drive (East <-> West) expect to drain the HV battery since the lights are long and you don't go far... therefore, HSD won't get much chance to naturally charge the battery. Hard acceleration to keep up with the yellow cabs and stopping fast at the next avenue red light does take the juice out of the HV battery. Expect to get about 35 MPG in this type of traffic pattern. That's with the ICE off at the stop lights. Imagine what a traditional car would get in that traffic.

I drive into the city twice a week during the rush hour to pick up my gf (I telecommute those days). I take Williamsburg bridge and goes up to mid-town from 1st Ave. I get about 70 MPG on that stretch due to the timing of the lights -- they turn green in domino affect at about 30mph. Once I reach 37th St, I need cross the city from 1st to 7th Ave. The HV battery would drain about 3-6 blocks depending on the traffic. From there, I head to Manhattan bridge to Brooklyn on BQE. Overall, I have been getting maybe 49 MPG ? (my average is lowering slowly) in this winter. The other 3 days, I drive to LI for work.

I got 52 MPG in warm weather and now 49.6 MPG. You should be able to get about 50 MPG if you watch your speed and momentum. I drive basically the same way I did with my 2000 Celica GT. Well, with gliding now since I CAN with Prius. I averaged 30 MPG with the Celica so you can reference that and guesstimate depending on what you are getting with the Corolla now. When the weather was warm and I still had my OEM rims/tires, I was able to get 52 MPG easily. I drive fast and aggressive sometimes but not too much because of the instant feedback from the MFD. I can not stand going lower than 50 MPG. I tend to ease up to keep my MPG above that point.

About two months ago, I went to Orlando Disney World for a week. I turned off the Smart Key System off using the off button before I left. When I got back, I turn SKS back on and saw the HV battery SOC at the same level. My 12-volt didn't get drained either as I was able to start the car. Even if you left the SKS on and drain the battery, it would be the 12-volt lead acid battery. When the car is off, the HV battery is protected because the circuit is completely disconnected.

Dennis