How many charges is the Prius Plug In good for?

the best thing is to charge it up right before driving. but nothing in the manual gives any details other than 'do not leave the car fully charged for long periods of time'. i charge mine for about an hour and a half in the morning in case i need to go somewhere unexpected, i will only need another hour for full charge. i don't think anyone knows what is best for the battery. i have heard it will lose about 30% over 3,ooo cycles, so 3%/year maybe? but this may not be correct.

 

I think we all talked about this early on when the PiP came out. But really, if you think about it, the battery is constantly being charged up and discharged while you're driving (regenerative braking). Granted, it may not be charged to its maximum allowable capacity, but it is possible to add quite a few EV miles (and at a much quicker rate than any charger). Personally, I don't worry about it. I do try to finish my charging right before I plan to use it though. Having a Level 2 charger helps in some cases.

 

I charge most any chance I get--which at most amounts to 3 times in a day, typically more like 1.5--to drive and expend the energy (not simply to have a full battery) with the following in mind: batteries are highly likely to improve markedly, and aftermarket packs are already available for the PiP. If I suffer some loss in capacity over the next few years I will happily reinvest those dollars saved in more battery.
I should however state that one of the reasons my family bought the Prius instead of the LEAF, Volt, etc, is due to Toyota's dogged insistence on long-term reliability, and I am hoping this car carries the standard.

 

I used to charge after midnight, but there have been days where I needed the car again later that day, so now I just charge it when I get home unless I am 200% sure I won't need it later that day. That said, the battery is covered by warranty, so I don't think you have to worry about it too much (unless you plan on keeping the car in storage).

 

i don't think the warranty is good for much except total failure.

 

I am still looking for the site in my history, but I read somewhere, I think on a DOE website, that the Prius NiMh battery is rated good for about 2,000 cycles according to them, and the Lithium Ion battery on the PiP was listed with a range 800-1400. I am fairly certain this was about the numbers that were reported.

 

ouch! at 300/year, that won't be long.

 

Below is a piece extract from wikipedia on the NiMH battery.

"Battery life cycle
As the Prius reached ten years of being available in the U.S. market, in February 2011 Consumer Reports decided to look at the lifetime of the Prius battery and the cost to replace it. The magazine tested a 2002 Toyota Prius with over 200,000 miles on it, and compared the results to the nearly identical 2001 Prius with 2,000 miles tested by Consumer Reports 10 years before. The comparison showed little difference in performance when tested for fuel economy and acceleration. Overall fuel economy of the 2001 model was 40.6 miles per US gallon (5.79 L/100 km; 48.8 mpg-imp) while the 2002 Prius with high mileage delivered 40.4 miles per US gallon (5.82 L/100 km; 48.5 mpg-imp). The magazine concluded that the effectiveness of the battery has not degraded over the long run.[114] The cost of replacing the battery varies between US$2,200 and US$2,600 from a Toyota dealer, but low-use units from salvage yards are available for around US$500.[114] One piece of research indicates it may be worthwhile to rebuild batteries using good blades from defective used batteries.[115]"

This exceeds the estimates posted earlier. I would bet the same holds for the lithium batteries. I will see if I can find more info on the lithium battery.

 

I agree with RBooker. I think there is a lot of misinformation about the prius battery and replacement time. I think the 2000 cycles is 0%-100%. And Toyota has designed and tested the batteries to minimize those effects, so I would be interested to see a more pro Toyota comparison of the cycle life.

 

while the pip battery is well protected by buffering at the high and low charge and discharge, it is a completely different animal than the non pip. both in chemistry and usage. especially for people who use it more like an ev, completely cycling it 5 days a week or more. all this is not to say it won't hold up 10 years on avaerage, but only that testing of a 2002 is completely unrelated.

 

R&D on batteries is ongoing. All EVs are using lithium batteries. Battery life cycle is a standard rating system and not a measure of the life expectancy of a battery I the real world. To be honest Lithium batteries are old technology. The primary reason lithium batteries have not penetrated the hybrid market is not reliability but cost. There is a small chance that the real world data WE generate may prove that current lithium batteries technology is not up to the task. If that is the case the engineers will have the data they need to I prove the technology.

By the way the PIP's control software does not allow the battery to "completely cycle". Since lithium batteries do not have a memory it's capacity is not deminished by where in the cycle nor the number of times it is charged.

 

admitedly, i know less than nothing about batteries. (except that one end is pos and the other neg) but i have a hard time accepting the statement that the 'number of times it is charged' does not diminish it's capacity.

 

It does, but the "damage" to the cells occurs leaving them in a very high, or low SOC (State Of Charge), Toyota controls this within certain predefined limits, I think I remember it being about %20 on the low end (this basically when it's emulating a standard Prius), and about %85 on high side, so they are using from roughly %20 to %85 of the SOC, or %65 of the packs capacity (which is why you get a little under 3KW of usable energy from a 4.4KW pack). Under these tightly controlled conditions it's a lot more than 2,000 cycles.
I am fairly certain I am little off on the bottom and top SOC percentages, but I am close.

 

Where in the cycle the battery is charged, and where it left sitting, has dramatic effects on Li-Ion.

All PEV have set buffers at the bottom (the far most dammaging region), and most, with the leaf being the exception, have keep the battery from ever getting 100% charges. (Even the leaf may have left a little above the "100%- user fill). Sitting fully discharged (well below the minimum SOC of the PiP) can destroy the battery very quickly. Sitting fully charged in hot weather can degrade it. Charging it to fully charged in hot weather is also damaging -- it adds even more heat.

Some related papers can be found here and here the most useful one I know from nrel is here which includes the following projected state of battery graph


Note that they presume 1 charge of the PHEV10 (10 is battery range) and one charge of the PHEV40 per driving day. Multiple charges per day would lead to an accelerated battery degrade. The model includes effects of both charging from the grid as well asd regen in CD and CS modes. Note the PHEV40 is assuming a 90SOC max, which is higher than current manufactures use-- which may be slightly accelerating the degradation on the PHEV40 -- also since they presume 1 full cycle per day its covering many more EV miles.

That said, the engineers at Toyota have a long history of considering the science and designing for reliability.

 

I was wondering what cycling a 4kWh battery 4x the cycles of a 16kWh battery would result in over the course of 200,000 ev miles.

 

You and Toyota time will tell, all they have now is "simulator tests" based on mfr claims for the cells, real work will take years to discover, but will probably be close. There is also an "aging" factor to lithium cells, they last only so many years (shelf life) irregardless of usage, so as they say "use it or lose it"

 

Check my math ...

200,000 ev miles ~ 17,000 plug-in charge cycles on 4kWh (3kWh user) vs 5,000 plug-in charge cycles on a 16kWh (10.4kWh user).

15 years at 15k combined, 80% ev = 12k ev, 180K ev miles total

Any idea what the regen charge cycles per mile would be, and if they are different for a larger battery than a smaller (Prius HV versus Prius PiP)

 

The Volt is made by GM, comparison of the different manufactures batteries should be accompanied by a manufacturer reliability coefficient to account for differences in manufacturer reliability

 

I'm not sure if we have that for the battery manufactures yet. I have a contact at Tesla in the battery group. I'll see if they can point to some data. I know they swear by the benefits of thermal management as well as capacity.