Is something Wrong with my Traction Battery?

You have two scangauges right?

Does it drop that fast when you shift into neutral?

Also, do you hear the battery fan turn on?

How much time passed while going from 5 to 2 bars? If its like less then a minute, while "charging" then I would be worried also... and would probably defer judgement/diagnostic to someone more knowledgeable on PC.

 

I would try to force charge the battery up to 8 bars, engage the EV mode and try how far the car can go at a steady slow speed (say 25 MPH or so, no accelerating, no braking if possible) until reaching two pinks. This would give you some sort of capacity estimate. If it is considerably less than a mile, I would start to worry. If you decide to do this experiment, don't forget to properly warm up the car beforehand, so the battery is at reasonable temperature. Low temperature could considerably "shrink" useful battery capacity.

You may also try to measure voltage at individual cells and look for the weak ones. I would do that preferably at 5 or 6 bars SOC (around the nominal 60% charge). This would also give you an opportunity to visually check the contacts.

Also, does it loose charge when parked overnight? This would also tell you something.

Overall, the symptoms you describe do not necessarily indicate any problem in my opinion. I think you have too few data to make any judgement now.

 

Would that be like some sort of electric ray gun, with bolts of electricity flying out of the car? I would say *that* would tell you something: run!



(Sorry for being a spelling nazi, but I found the image amusing.)

Tom

 

Yes, exactly. Press the brake pedal firmly and floor the gas. Don't be afraid to floor it, the ECU will actually take care of the ICE itself and will regulate the torque in order to produce desired charging current. Hold it in that state until you reach full SOC (which is indeed around 80%). It will take some time, like 2 or 3 minutes, according your starting SOC. But warm up the car beforehand.

Yes, that's what I would do. Take out the cover and have a look around the pack, inspect the contacts and measure the voltage of individual modules. There should be no big difference among the modules, less than 0.1V - in fact, I would expect them to be within few hundreds of volt apart when healthy. It would be even better to measure the voltage under some load, but I am not sure how to muster that. If one or more of the modules are more than 0.1V apart, something is wrong I guess; on the other hand, there might be a dead module still showing good voltage under no load, so this is not a definite test.

Don't do it if you don't feel comfortable messing around the EV battery.

OK, so no problem here.

This is normal. The car prefers the electric propulsion when the ICE is cold for a first few minutes of driving.

I wouldn't do that. I don't think you are helping anything. The car prefers to use the battery for a reason. It is quite normal to lose two or even three bars when starting to drive with a dead-cold engine.

 

Sorry Tom, I am not a native speaker - English is a second language for me . But I can surely understand why you found my mistake amusing . Well, *that* would definitely send a clear message... :madgrin:

 

I *am* a native English speaker, and pretty good at it as well, but even so I have trouble with "loose" and "lose". I have to think about it every time. English has a lot of stupid words like that. I suppose that's what happens when you cobble together a language from several other languages.

Btw, your English is excellent.

Tom

 

Hi spinkao. Do you know of any data points for this test? For example, are there any reference values for how far a battery in pristine condition should propel the car in this type of test? I mean actual data from people who have performed such a test.

 

I did, but I don't know any other people who possibly tried this, at least not personally. The EV range depends on the driving style - for me, it was about 2km (1.2 miles) at a steady speed, no accelerating, no braking, going approx 40-45km/h (25-28MPH). It is much less if you brake and accelerate, like you do when stuck in a traffic jam.

This exact figure (2km at 45km/h) is also stated in my owner's manual that came with the car, so it is the "official" figure. If you google Toyota prius ev range 2km, you can find that other people achieved similar results (if you google just Toyota Prius ev range without the 2km figure, you will mostly get results for various plug-in versions).

That's why I proposed this test; I think that under controlled conditions (flat ground, steady speed at 25MPH), it should be easily reproducible (it was in my case) and will tell you something about the traction battery capacity. I think that if it is considerably less than a mile, you may start to worry.

 

Thank you spinkao.

BTW. I was just doing some quick calculations and came to a similar conclusion.

- The Prius battery is ideally approx 1.3kW-hr capacity.

- The change in SOC from the point where you just (first) get all green bars down to where it just drops to 2 pink bars is approx 30% (75%-45%).

- So the energy available for this test is approx 1.3*0.3 = 0.39 kW-hrs.

- A good figure for easy driving with everything optimal is about 8 km per kW-hr. (??? guestimate based on other EV data, it might be a bit optimistic. Can anyone confirm if this is about right for the prius).

- So the Prius should theoretically go approx 0.39 * 8 = 3.1 km (under optimistic conditions)

So based on that rough calculation I'd say 3km would be a pretty good figure to aim for under the most ideal conditions (though I'm sure it would probably be a little less in practice, I'd be happy with about 2km).

It would be really nice if we could get a few people to do the test and build up some information on what is typical for Priuses of various ages and mileages. I think the main issue here is that the US priuses don't have the EV button so that excludes the majority of users here from easily doing the test.

 

You could probably aim at the 3km mark if you accelerate going downhill, using no "internal" energy at all for the initial acceleration, and then enter the "measured strip" already at the cruising speed (45km/h) - essentially a flying start. At the end, you would put the car in neutral and let it glide until stillstand. That way, maybe you might even exceed the 3km mark a little . The 2km ride included the initial acceleration.

Actually, that would make for a nice competition . Imagine two Priuses, standing side by side with their batteries fully charged... a scantily-clad handsome girl waves the chequered flag and off we go! Which guy can go further in the EV mode? Which one can outglide the other in the final stretch? It would be like a dragster race :madgrin:! I can see the cheering crowds already... :first:

Streetracers, do you read this? That's the way to compete !