Traction battery life-usage vs. age

I'm not aware of statistics, but my guess is that:

1) age is worse than miles logged
2) miles driven on mountainous terrain is worse than miles driven on relatively flat terrain.

 

Didn't someone on here post a chart showing how the different types of useage affects the battery? Probably BobWilson but I could be wrong.

I think it went along the lines that mild discharges such as a 60 mph commute is good for the battery, but many full discharges such as the use my taxi Prius gets is not good for it.

Patrick is right too - heat is the enemy of the battery. So if you live in a desert then park the car in the shade whenever you can, but also the bettery getting hot on hills or people blocking the back seat vents is not good either.

But equally I wouldn't get too paranoid about the battery. They appear to be very resilient and long lasting. There are a few Prius cabs out there will 100's of thousands of miles and still going strong. The only problems seem to occur after serious accident damage.

 

I wish to restate your question (I do not have an answer)

In the big city taxi tests where they got huge miles before battery failure, the taxis ran 3 shifts a day, the HV Battery was virtually always watched over by a computer, providing it's every need.

In my Prius, it sits 12 hours a day idle, turned off at what ever state it was when I powered down. A future Plug In Prius would run the computers while it was charging.

How much battery life am I losing because my battery is not being tended to 24/7 by it's ECU?

My guess is "not much", but it is just a guess.

(The Gen I batteries were more failure prone than Gen II and III batteries, so some raw data may be skewed between the 2003 and 2004 model years)

 

Hi Patrick. While I totally agree with you on point 2, I'd go the other way around on point one. I'd say miles logged is a better indicator of battery wear than is age.

Heres why. NiMH batteries age and lose capacity due to both calendar aging and due to cycling (usage) but Ive read that the calendar aging is actually fairly slow and that good quality NiMH batteries might be good for 25 years or more in terms of straight chronological aging.

So realistically its going to be the amount of cycling, particularly under heavy usage (as per very hot conditions or the mountainous terrain as you mention) which is going to have the biggest impact on battery aging.

Of course we may not always know how much or how hard the batteries have been cycled, and its always possible that a car with low mileage could have had more hard cycling of the battery than a car with higher mileage. Given no other info than the age and the mileage however, youd have to conclude on balance of probability that the higher mileage one had seen more hard cycling and therefore was the "oldest", irrespective of calendar age.

 

I have heard that the Li ion batteries have an age issue independant of use... don't some of the totally or mostly electric cars use them?

 

I thought I heard for a Lithium battery it will be noticeably degraded in ten years, regardless of usage. Not entirely sure of that.

The Prius of course uses NiMH, but if you have a plug-in conversion, those are usually Lithium. Tesla and other high-end EVs are lithium (not the NEVs or the California EVs from last decade).