Of course I won't be driving it 200,000 miles, I expect to replace it with a Nissan Leaf ASAP FYI, not many Gen 2 HV Batteries have failed yet, and it has been out since 2004 (I had one), some of the Gen 1 HV batteries have started to fail, but those are from 1999 to 2003 model years, so that is at least 7 to 11 years age wise.
Sadly, I think most of them will last right up to the time the Prius is totaled. (I am not voting, as I don't own a Gen III, but I want to, as the batteries did not change)
They're warranteed for 150,000 miles in California, so I expect 151,000 miles out of mine. What I wonder, though, is how will mileage be affected by the battery's decay over time? Will the car get lower mileage at 50,000 and 100,000 miles?
Where's the option for "I have no idea"? Given the warranty duration (150k), and the typical distribution of a bell curve, I would bet that the MTBF must be high enough that 150k is still on the thin part of the curve - it would get very expensive for Toyota if 40% (or even 10%) of the batteries failed before the warranty expired. We don't know the shape of the curve, however - it may be more of a spike in which case they would likely park it right at 151k.
Compared to the NHW11 modules, the NHW20/ZVW30 modules are tanks: Here I'm helping to replace a 2001 traction battery that went 250,000 miles: Add to that I've studied traction battery failure and recovery modes: This includes what sort of abuse shortens their life: So as an individual, I fully expect the car to be lost in an accident before the HV traction battery dies. As for those who follow PriusChat and 'get a clue,' they can drive to extend HV life since I share what I've learned here and other forums. So I see +300k miles being more than possible ... it is what I would expect to see. Personally, I won't worry about traction battery life until after 625k miles (1,000,000 km.) Now there are risk factors, especially for NHW11 drivers: hills - descending hills with heavy regen will 'heat pump' the batteries. Mitigation, use "B" as much as possible. heat - heat is the enemy so park in shade during summer if possible. high-speed, stop and go - less bad than hills, it can 'heat pump' the batteries. So far, we don't have enough information about the NHW20/ZVW30 modules to draw any conclusions . . . they aren't failing often enough to see patterns. Even the NHW11 traction battery failures are thin. Bob Wilson
I confess I am dubious about interpolating taxis to normal drivers, as the computer never quits 'protecting' a taxi battery. A big city taxi is going to be in Ready mode almost 24/7, so the cab company gets the most profit possible, but I sleep 8 hours a day and work 8 hours a day, so my battery is not pampered as much as a taxi battery, as my car is off. Will this make a difference? I do not know, and at 30,000 miles a year, it may take me 12 years to find out.
Reduced battery capacity due to age does not seem to affect mpg. See: http://avt.inel.gov/pdf/hev/end_of_life_test_1.pdf. These cars had 160,000 miles and HVB capacities as low as 40 % of new. Reduced capacity might affect heavy acceleration which wasn't tested.
Aside from those statements conflicting with themselves , can you elaborate a bit more on the risks? Pretty much anything that would create significant heat over an extended duration?
Charging NiMH batteries is exothermic, it releases heat along with the ohmic heating. Discharging batteries had ohmic heating that reduces the endothermic effect (aka., discharging does not cool the batteries.) So what happens is descending a hill forces a charge on the battery and it warms up. When climbing the next hill, there is insufficient time to dissipate the heat. So the next descent 'pumps' the battery temperature higher. Inside the battery, a very small amount of gas is generated, losses that are inescapable. Normally this small mix of hydrogen and oxygen simply recombines over time and is not a big deal. But the problem is heating the battery increases the internal pressure. This leads to the gas and a little bit of KOH seeping out the terminals. Over time, the losses add up, the electrolyte become un-electrolyte and a cell fails ... which fails a module. For more technical details: Prius Battery Photos The cooler you can keep the batter in spring, summer and fall, the longer it will last. During the winter, the goal is to try and keep it above freezing for optimum performance. Bob Wilson
