HV Battery care " parking in the red

What sort of fuel economy do you typically get on these trips with your battery management strategy?

 

hmmm

 

hmmm, never thought of that

 

I was under the impression that keeping the NiMH battery within a narrowly confined operating limit helped prolong its life

 

+1. The car is programmed to keep HV Battery charge at about 60% on average.

 

My Prius came with an ECU that takes care of the HV battery for me.

I don't have to worry about such things as full peak charge, the typical pulse and glide, going warp steal, rolling windows up and down or cycling my battery.

I can just enjoy driving this great car.

 

NiMH batteries don't have a "memory" like the old mercury batteries. Deep cycles can actually be harmful. That's why the Prius works so hard to keep it between 40% and 80%. I paid good money to have the car worry about the battery.

 

Everybody needs a hobby :_>

 

Somebody needs a life, you mean.
:ninja:

ZC1

 

:hand:

 

How long do your R/C car batteries last? Can you get 150,000 miles out of a battery?

 

Sorry that I came off snobby. I am also trying to share information. But to be blunt, I haven't read anything in the Toyota owners manuals or service manuals that indicates that I need to do anything regarding maintaining the HV Battery. The tech training manual describes how the Battery ECU and the HV ECU work together to try to keep the SOC as near 60% as possible.


You seem to be suggesting that we should manipulate the charging/discharging in a way that wasn't programmed in by Toyota. They provide a 10 year /150,000 mile warranty for the battery in Calif emissions states. Do you think they (Toyota) do not understand how they should maintain the battery?

 

Snobby, no. (Usually. ) Skepticism, yes. A healthy dose of it is inevitable when someone's very first post runs contrary to the incredible amount of collective knowledge and experience in these parts.

So while you're sharing, please share your answer to my question. What is your fuel economy with your battery management strategy?

 

Not snobby, but we want to make sure that when people come to PriusChat, they don't get misleading information or bad advice.

I may well be mistaken here, but I'm pretty sure that. . . .

"Memory Effect" is a very specific situation that applies to NiCd batteries, although people have adopted the term to refer to any situation where a battery appears to hold less charge than expected.

In NiCd batteries Memory Effect was a situation where a battery is repeatedly discharged to an identical state before recharging. The battery apparently develops a short duration voltage drop at this discharge state which can be a problem for some electronic devices. While this sounds like what you are doing with your "cycling" of the battery, and as such would seem to indicate that you are going to induce a "memory effect" into your battery, it is important to remember that the Prius uses NiMH, and not NiCd.

It is also important to note that NiCd batteries tolerate deep discharge better than many other rechargable battries.

As for the more general use of the term, some of the potential causes of reduced battery capacity are:

Dendritic shorting, in NiCd batteries, is caused by leaving a battery unused for an extended period of time. Thin conductive crystals can form which penetrate the membrane between the electrodes and create internal shorts.

Voltage Depression - Caused by repeated over-charging, which causes the formation of small crystals of electrolyte on the plates. This increases internal resistance and reduces the voltage of some of the cells in the battery.

Deep Discharge can cause individual cells to reverse charge if they are reduced to zero charge before the rest of the pack. This will reduce the output of the pack as a whole.

Fortunately, since the Prius uses NiMH, it won't suffer dendritic shorting. Since it charges and discharges to different levels all the time as you are driving, actual memory effect isn't a concern. Furthermore, the vehicle protects itself from well-meaning attempts such as yours so that it won't experience repeated over-charging (voltage depression) or deep discharge. It does this by forcing the vehicle to begin recharging itself when it reaches about 40% of a full charge (and dispaying this 40% state on the "Energy" screen as an empty battery), and by cutting off all charging of the battery when it reaches about 80% of a full charge (and displaying this 80% state on the "Energy" screen as a full battery).

So first, you are never really fully discharging nor fully charging the battery with your process. Second, you are attempting to protect your battery from effects it will not experience. Third, the battery management system is protecting itself from you. Fourth, all that heat that you are generating in the battery, by charging and discharging it as much as the vehicle will let you, is energy that could have been put to better use pushing the car down the road. As such the vehicle will need to generate more energy for the purpose of moving itself than it otherwise would have. In other words, you aren't really gaining much, but you are reducing you MPG for each tank of gasoline you use.

 

They don't call the battery sub-c, but [SIZE=-1]prismatic.
Plastic Case Prismatic Module | Panasonic EV Energy Co., Ltd.

Ken@Japan


[/SIZE]

 

It amuses me that people think they can get better results than multi-million dollar engineering projects. Then they expect the more technically minded among us to accept unverifiable hearsay or anecdotal evidence over the results gleaned by trained and experienced scientists and engineers.

I choose to believe those who are rigorous in their approach. I, by default, accept well known principles of science and engineering until VERIFIABLE evidence to the contrary is presented.

In the context of this discussion, I'll believe what Toyota says is best for the HV battery. They have a significant risk in failure because they have to replace batteries that fail before 150,000 miles. They have an even larger risk because if batteries fail en masse their customer base will defect.