What constitutes a charge and recharge?

The Prius battery -never- goes through a "charge" cycle. It is constantly being discharged a bit and recharged a bit.

This is the whole idea of the design, never discharge below about 40% and never charge above about 80%.

I suppose if you managed to get it down to 40% you could say it was then being charged, but that happens all the time and only partially. Ditto if you get all green bars. The system then tries to "use up" some of that charge, but it will still dump charge into the battery on braking if you get it down even slightly.

So there is no real "charge/discharge" cycle. The battery is constantly being charged and discharged as needed, never letting the SOC (state of charge) get below about 40% and above about 80%.

 

"Recently" totalled in an accident, there was a Gen 1 Prius (Owner: Jesse) with over 300K miles on it w/ the original battery. A few years back...there was a Prius taxi in Canada w/ over 100K miles on the original battery. Except for, maybe, the rare manufacturing defect, I have never heard of a Prius traction battery wearing out (except maybe for some bad mods that damaged things).

 

Obviously there is a finite limit to charge cycles. The reason the question is hard to answer is that it depends on the depth of the discharge/charge cycle. Some types of batteries that can only go through a couple of hundred full cycles can go for thousands of shallow cycles. The answer also depends on how you define dead. Is a battery at 50% capacity still alive, or is it dead?

The Prius uses a very shallow cycle, and it will still function well at 50% battery capacity. Because of this the traction battery will last for over 200,000 miles, on the average going through several small cycles for each of those miles.

Tom

 

I've owned three Toyota hybrids (none of which have had drivetrain modifications) and have had two traction battery failures so far:

2001 Prius at 61K miles, DTC P3006 Battery SOC Uneven

2006 HiHy 4WD-i at 26K miles:
DTC P0A80 Replace Hybrid Battery Pack
DTC C1259 HV System Regenerative Malfunction
DTC C1310 Malfunction in HV System

I have 56K miles on the 2004 Prius and the SOC gauge seems to show 7 and 8 green bars more than before - maybe this is early warning of an impending failure?

If you look at my Classic Prius Repairs poll, you will see five out of 32 respondents who have reported the need to replace the traction battery.
http://priuschat.com/forums/generation-1-prius-discussion/45766-classic-prius-repairs.html

 

by the way, do anyone know if the MFC display actually show the battery being charged to full level? I seem that sometime in the last four months. it doesn't happen all time. and before last four months, I have never seem that happen.

 

One thing it depends on a lot is your driving cycle. I leave my house and go down a long hill (about three miles of hill, losing about 800 feet of altitude)

Depending on how I hit stoplights, if any, temperature, etc. that generally gets me to seven or eight bars by the end.

But I believe if I launched into regular stop and go city traffic on the level, or a level Interstate, I'd probably never see eight bars.

By the way, I fear this may mean I'm using up my battery life faster than do flatlanders.

 

When all 8 bars are full, the battery is at ~80% SOC. When all the bars are empty its at ~40% SOC. By default the controller tries to maintain the battery at 60% or about 6 bars (scale is non-linear). The car will not normally charge above six bars unless you do something to add more charge than it was expecting like drive down a long hill, or decelerate off the freeway. After that the car will quickly use a little more electric drive to burn off the extra charge and get the battery back down to 60%. As you approach 80 or 40% the car gets much more aggressive about moving back towards 60%.

Rob

 

Please refer to following chart which shows how the battery SOC is maintained.
Anyway, the whole presentations are worth to read.
For the original 1997 NHW10 Prius.
John's Stuff - Toyota Prius THS Presentation 1
For 2004 NHW20 Prius.
John's Stuff - Toyota Prius - 2004 Tech Presentation 1

Ken@Japan

 

I agree with that thought, given my experience with failed traction batteries and the fact that I live at 1,100 ft. elevation and commute to sealevel.