500,000 km 2008 Prius Taxi

I remember reading the reason Toyota chose the bearings for low rolling resistence reason. Any noticable difference in MPG with the aftermarket bearings?

 

Hi
I am in Cairns Queensland Australia and we have had Prius taxis since 2004. The cars generally do 550,000km before there retired. I own a workshop and maintain 16 prius taxis.
I replace the inverter pump and coolant, remove and clean the hv cooling fan and replace the transaxle oil every 80,000km.
Hv batteries fail from 350-400,000 km
Depending on the drivers the transaxles fail (mechanical failure) from 250,000km on. If there caught early enough i rebuild the transaxles.
The cars are serviced every 3 weeks like clockwork. They usually do 10,000km in that time.

 

Now these are great statistics!

Are the HV batteries rebuildable at 400,000 km? I see two failure modes: random cell death, leaving the rest of the battery good, or chronic overheating, which kills all modules in the middle.

In what way are the transaxles usually failing? How do you think a particular driver is able to kill them faster or make them last longer? And, what's the difference between catching a failing trans early and rebuilding vs later/bombed?

 

How many people are in the workshop to maintain 16 Prius taxis? I am wondering how it compares to keep 16 non-hybrid taxis running.

 

I suppose in cold climate the ICE is ON more frequently (to provide heat to the cabin) thus the HV battery may be at higher SOC thus more risk of failure.

 

It actually is likely to be the reverse. In another thread (http://priuschat.com/forums/gen-iii...-dead-126000km-up-atleast-3-taxis-i-know.html) it appears that heat is helping to kill the battery, and as Cairns is a tropical town, the heat is generally pretty high there. If the drivers do not run their a/c regularly, the battery is going to suffer from some heat exhaustion and thus is likely to fail earlier.

shaneb - if you do not check the battery cooling fan, it might be something to add to your checklist.

 

But running the a/c all day in a 10 hour taxi shift will warm up the HV battery somewhat. I've had my car get upset with the heat in the UK once during a hot (for us) day of 30c where the a/c was working overtime and the car was doing hard town work (accelerate, brake, repeat x 10 hours). The car suddenly started to rev at about 2500 rpm and tried to use the HV battery as little as possible (7/8 bars all the time and arrows going in and out quickly). The HV fan did come on once during this time too.

The car drove as normal and no warnings and messages were displayed. I had the dealers check it as I was a little concerned but there were no unusual error codes flagged. I guess the car was just protecting itself.

But perhaps heat can cause issues indirectly - such as excessive a/c and ev use in the heat?

 

Not running the A/C makes the battery heating problem worse. The battery fan draws air from the cabin. The compressor current draw from the HV battery is 5A +/-. Compare that to 100A+/- for max assist and regen. Heating is quadratic in current. 100A generates 400 times the Ohmic heating compared to 5A. Do use A/C, don't use EV.

 

But how do you not use ev (ev not EV mode) when in town/city traffic as a cab? You can't help but crawl in traffic on tthe electric.

 

One way I conserve the HV charge is to glide in neutral when the charge shows mostly blue bars or green. In city traffic one must remember to put the car in drive again for normal braking or use brake gear. Although I have never had a overheat problem. But always consider HV Battery cooling, either window air or AC. Of course I do not drive a taxi. :cheer2:

 

Not running the A/C makes the battery heating problem worse. The battery fan draws air from the cabin. The compressor current draw from the HV battery is 5A +/-. Compare that to 100A+/- for max assist and regen. Heating is quadratic in current. 100A generates 400 times the Ohmic heating compared to 5A. Do use A/C, don't use EV.

+1 for that, whenever I get a chance I roll down the rear window and try to get more fresh air for the HV battery, in return I need to clean the fan more often thanks to Colorado`s dry and dusty air but oh well, I like to do it anyway.

BTW, as of today I`ve got 309K on the clock, getting close to 500K Kms eh

 

I think it may have been trying to burn off the high charge in the battery. Maybe someone who lives in the hills could comment on what happens after the battery is fully charged from a downhill recharge. I've had my Gen2 run the ICE after a 5 mile downhill that took the SOC up to 80.5% (Scangauge). The ICE stopped after the SOC went below 80%.

 

I'm not sure it was that either. I experience that situation whenever I go down a steep hill and the battery goes completely full 8/8 and then some. When I get to the bottom the engine is revving burning no fuel to 'burn' off the excess charge. But when you press the accelerator the revs drop.

When I experienced that possible HV overheat the engine was revving like a normal car on a cold start, the battery arrows were going in and out very quickly, though the battey wasn't full. I'm sure I had overcooked it and since try not to use a/c in town on really hot days.

I think the use of continual charge/discharge and heavy a/c use (coming from the HV battery) just caused it to get hot internally. I'm guessing I just wasn't giving it a break all day. Perhaps that's what's happening with cabs? They're not really able to pull over for a rest if they're busy and the environment they work in doesn't help the car either. Does the gen3 use the HV much more than the gen2 in towns? Could this excessive and harsh use with a less robust HV battery be causing the premature failures we're now seeing?

 

England is not Arizona, you should not have overheat problems. Either you are driving the car very robustly (which I doubt) or you are no longer getting proper air flow thru the HV Battery. Just for curiosity, what is your average MPG?

 

I don't imagine that the city crawl is much of a problem for the battery.

Lets say you manage 10 miles an hour, and a mile takes 250 wh. Then the battery has supplied 2.5 kwh, for an average discharge of 2500 watts. That draw is dwarfed by the AC.

I cannot think of a good strategy for hot and humid, but just hot can be handled with high flow ventilation. Keep the battery cool, be damned the passengers