Odd experience at higher speed tonight

When the traction battery charge is really low then yes it does make the engine work harder and rev out more to try and get power. However I'm not sure why your traction battery would have been in such a low state of charge.

At 50MPH the engine should be running most of the time and the state of charge should normally be sitting up around 5 or 6 bars.

- Did you climb any really large hills just prior to this?
- Was the car still warming up during this event?

 

Ok I just noticed that part. Keep your eye on the SOC (state of charge) and watch out for any very rapid swings (like 7 bars down to 2 or the other way around). It might indicate that you've got a weak battery pack.

Also note that one place where you can get a rapid SOC swing is starting out with a cold engine. If you have to drive hard or climb a hill with engine still cold then it can use up the battery really fast. Better to let it warm up in park for about 30 to 40 seconds if you need to drive hard from the get go.

 

You could also have a weak 12v battery. Is the 12v the original? If it is, it may be at the end of its useful life. My first step would be to replace the 12v battery and see how the car behaves.

 

Rusty, I live in Eldorado and have the same problem. It is uphill all the way from the house to Bobcat crossing, 4 miles at 100 feet/mile of elevation gain. I can start off with 7 bars on the battery gauge, but by the time I get there it is one or two bars left. I can floor it to pass someone, but the engine is maxed out and instantaneous mileage drops down into the teens. I can imagine, if you start out from Galisteo, you might be down to 2 bars before you even get to the freeway, especially pushing hard over Lamy hill. On the way back, it can be a similar problem, such as starting out from e.g. Zafarano/Rodeo, going uphill to I-25, then getting on I-25 at the uphill onramp and getting up to 75 MPH so as not to get clobbered.

 

I don't know the region rustystew, but it sounds about right if you're starting out up hills. Try the trick of letting it warm up for about 45 seconds (in park) and see if that helps

 

Unfortunately, for us, yes. I just wish there was a way to scale back assist on the mild inclines like there is in my Insight.

 

You probably don't need an EBH unless you get really cold winters. When you let it warm up while in "park" it pre-charges the battery a bit before you take off. Also the pre-warmed engine doesn't hit so much on the battery for assistance in the first minute or so.

The small 1.5L atkinson-cycle engine just doesn't provide a huge amount of power for 3500 pound Prius. The electric motor is meant to offset this by providing extra power for acceleration. So (depending upon your expectations) the prius can be a bit under-powered when the traction battery is too low. What you're described is just what it does, engine rev's harder to try to provide enough power when the SOC is very low.

The best thing you can do is to monitor your state of charge more closely until you're used to it. Try to figure out what part of your drive is depleting it and see if any modifications to technique can help maintain better SOC in this area.

 

Starting up and waiting 50 seconds before you move (or turn on the AC!) is the best advice. Also, if you have an EV button, don't use it.

 

I went through the same thing not long ago, and it seems not so much a hardware problem as soft(as in the head)ware.

Having gone through years of auto transmission vehicles, have gotten used to a passing, or kick-down gear. Need to pass, whomp the accelerator and the trans shifts to a lower gear. Kinda like an afterburner.

Besides the hybrid part of the equation, the Prius also has a constant variable transaxle, so there's no 'lower gear' to kick down to. Couple this with ECU control over the whole process and there doesn't seem to be any real 'passing' gear. Maybe they can add a passing button or program the thing to dump full power to the wheels when the accelerator is rapidly mashed.

In the meantime, just have to learn the limitations of a new vehicle and drive accordingly. After that one experience, I'll not be doing any "squeaker" passing in the future. Little too close for comfort.

 

I just wanted to add something to the good advice - not sure if it was made clear why the 50 second wait is a good idea, rustystew.

In the first 50 seconds-minute of turning on your car even though you hear the engine running, all of your acceleration comes from the battery. After that the car rapidly recharges the battery still in warmup mode to get you back to a normal state of charge. That's why people suggest letting it sit if you know you're going all uphill right away for a long time. I've tried idling for a minute or so from time to time, but always just found it got me worse mileage in my particular situation (read: terrain), so I avoid it.

However, I would personally avoid getting up to high speeds like a highway within the first 50 seconds of operation, and it's probably good for you to idle at least a little if you do that routinely. I sometimes find myself at two purple bars after startup just from getting up to 40 mph up a slight hill. If you need the engine badly during this phase, you'll get it - but with aggressively high RPMs just like you described.

 

That's exactly what happens if you fully depress the accelerator, which is why the engine straight away jumps to high RPM - you are getting full power and you will begin to accelerate.

 

You have the cause and effect reversed. The low battery SOC is why your ICE revved up without producing much acceleration. Much of the power of the ICE was being used to recharge the HV battery, so only a portion was left for acceleration.

Tom

 

Yeah that explains it, you definitely should let it warm up (in park).

BTW. The reason I always say to use "park" is that it allows the engine to generate electrical power while it's at idle. Because of the prius's unique power split transmission it is unable to generate electrical power from the engine without also providing torque to the wheels. As such it wont allow electrical power generation if you're stopped (eg to warm up) in either "N" or in "D" with your foot on the brake.

If you're in "P" then while it's warming up you should see the following energy screen (see attachment). So this give the added benefit of giving the battery a little bit of extra charge as well as warming up.