Power loss & low battery during climb

Do you hit green territory before your climb & then notice this?

 

I've experienced this when climbing the steep sections of I-80 on the way to Reno but usually only in the cold of winter but I was never speed limited. I did feel the power loss though.

 

I've experienced this with our 2009s with under 20k miles on them. Going from Silverthorne East on I-70 to the Eisenhower Tunnel is an elvation climb from 8,751 feet to 11,158 feet over the course of about 8 miles. Even with a green battery at the bottom, I run out of juice about 3/4 of the way up and can only go about 50 - 55 mph with the ICE screaming. It would probably help if I started out at 55 mph instead of trying to maintain 65 mph and if I didn't use cruise control.

 

What's the condition of your 12v battery? Is it the original? If so, it probably needs to be replaced.

 

I'd concur w/the experiences of F8L and M8s. I'm not sure there's anything to be concerned about.

I've easily "depleted" the HV battery when climbing hills on highway 152 (connects 101 and I-5) between San Jose and the LA area or Vegas. ICE is screaming and there is much less power available, besides the HV battery looking low on the MFD. (Even at 1 bar, state of charge is actually ~40%, see Prius Palm Mileage Simulator). I can't recall if I was "speed limited" at 50 or 55 mph but definitely had no "reserve power" left to increase my speed much or at all.

As for checking the 12 volt battery condition, I'd recommend checking it via http://priuschat.com/forums/newbie-forum/73400-weird-stuff-happening-mpgs-dropping-test-battery.html after the car has sat overnight.

Since the OP mentions "around town" and lives in SF, that can easily happen if you let the HV battery run low via lots of stop and go/idling, esp. w/the AC on. I did it today in city traffic (SoC was showing in the 40s, percentage-wise). Some parts of SF are rather hilly.

 

Can't speak for this myself. Have a friend that drives an older Prius......takes yearly trips to Colorado.......he tells me that there are some mountains that he just barely makes it over....forget 50 MPH.......he's doing 30 MPH when he finally reaches the summit.

I'm guessing that this is normal in a Gen II

 

i've learned it's all about weight and speed at which you approach. you will hold power and possibly climb in speed if you start out around 70mph... it's like an ultimate high speed steath (only my opinion.. a few others have said something similar)

if it's only you, you can do this.. if it's you and a car full of stuff or people... you will not make it over at speed... period...

if your mileage is dropping during normal commute and you see acceleration problems in town (seat of your pants or battery soc) then it might be something that i've been chatting about for a while which... idk.. maybe i'm the only one... ignition coils. i've had one go out on this car and the car basically didn't tell me anything. i had a mechanic check it too. i found out by pulling coil wires. when coil 1 was pulled, the engine didn't notice a difference, therefore it failed. they are not exactly cheap either.

back to topic...

 

For goodness sake, why haven't they just put a fresh battery in and see if that fixes it? Over time, the battery will degrade and not hold as much energy as it did when new. Voltage depression is well documented with NiMH chemistry. It is in some ways analogous to an engine losing compression, and therefore power/efficiency, with wear and tear. Theoretically, it can be fixed via reconditioning. It would also help too to determine if there are sources of inefficiency, such as the 12V battery already mentioned by firepa63, broken down transaxle fluid, sticky brake calipers/shoes, poor A/C performance (compressor running at full output all the time) etc.

 

Yes that's what I think as well.

I think that what's causing the confusion about "what's normal" here is that if a climb is long enough then, regardless of how good/new is the traction battery, then you can run out of juice for electric boost and then the car can feel sluggish. This is why other users can say they've experienced the same thing as "normal" whereas the OP is sure it's abnormal.

The OP's traction battery has degraded somewhat (maybe a bit, maybe a lot), so certain passes that previously didn't fully drain the battery now do so.

Maybe Toyota is pretending not to know what's going on so that they don't have to do warranty on the battery?

 

How about battery overheating? Do you hear the battery cooling fan in the rear running when this happens? Perhaps the vent beside the rear passenger seat might be blocked? I knew one guy who experienced similar problems and it turned out that that vent was simply blocked by a rear passenger seatbelt over it.

 

Yeah, or dog hair in the vent.

 

I've never experienced the speed limiting issue when this happens. I'm also not sure why the 12v battery is being implicated as the cause. We are not talking about little mole hills here. These are long steep grades that simply drain the HV battery.

 

If the 12V battery is going out, then there is a lot of power being drawn off the HV battery to run the DC-DC converter to keep it charged. What Tone88 describes makes sense if the car is having to charge the HV battery with the engine at the same time that it is trying to climb the pass.

 

Get to Luscious Garage (or Art's Automotive) in SF for a second opinion.

JeffD

 

This is driver style mostly. If you start going up a steep slope in any vehicle with limited power and you don't floor it to begin with, or let off the pedal for a second only to reapply it hoping that will give you more juice (as my mother and sister usually do) you lose quite a bit of momentum and slow down to the point where you can't reaccelerate only stop yourself from decelerating more.

I live in the CO Rockies with a GenII and loaded with me + passenger + ski cargo can do all the passes on I-70 at 70mph to 80mph no problem and keep with the flow of traffic. When you start the climb, push the pedal to the floor. Do not for any reason let up on that pedal. If you start at 70, you will end at 70. If you start at 80, you will end at 80. If you start at 65, then slow down slightly to 60 because you don't want to floor it the whole time or just to readjust your foot, then you will end at 60. If you do that a couple times and your speed drops to 50, then you will end at 50. It is not a hard concept. There is plenty of power to keep it going the same speed you started up the worst stretch of high speed interstate in the country. There is not enough power to start from 0 and accelerate to 80 on that same incline.

Once your battery is gone, you basically just halved your output power. Not only is the engine working to move you forwards, it is working to recharge the battery, and drive all the electrics by itself. (Well sorta kinda, it is never "by itself" but the analogy works)

The same phenomenon can be seen with my mother driving her 3.5L V6 with 275 horsepower up the same slope. It does have enough power to reaccelerate, but if it accelerated like that on flat ground that old man from Office Space would beat it in a drag race. She drives at the speed limit up to a car that cannot go fast and slows to match their speed, then tries to overtake in the left lane which is a snail race, only to slow down to merge back into the middle lane... If you do this (which pretty much everyone does) in a Prius, you will not make it to the top at speed.