[unclehan]

What happens after the battery get fully charged? Does the engine shut off and simply let the motor power the vehicle? Because if the load is low and the engine is running, then the extra power made will be wasted.

 

[john1701a]

What happens after the battery get fully charged?

You've struck upon a very, very common misconception among newbies. Welcome!

Many people equate the charging to work like the rechargeable batteries they've been using for countless years now. When it gets drained to a "low" level, charging begins and continues until "high" is reached.

This is NOT true for Prius. There is no cycling like that. Thank goodness. If there was, the battery-life would be much shorter, like people expect with regular rechargeables. This is the primary reason why the battery-pack is expected to last the entire lifetime of the vehicle.

Instead, the Prius battery-pack is in an almost constant state of charge & discharge. A little bit of electricity gets used, then a little bit gets immediately restored. So the charge-level typically hovers around the middle... which leads to the common question of: Why haven't I ever seen "full"?

 

[unclehan]

What happens after the battery get fully charged?




Instead, the Prius battery-pack is in an almost constant state of charge & discharge. A little bit of electricity gets used, then a little bit gets immediately restored. So the charge-level typically hovers around the middle... which leads to the common question of: Why haven't I ever seen "full"?

Okay. I see.

But what if you are under light load like cruising at a low speed? Either the engine gets turned on or off. If the engine get turned on, it'll produce way too much power and this have to go to the batteries. This will make the battery charge go up , unless the engine is working at a lower speed (inefficient). But if you turn off the engine, the car will be solely on the battery and this in turn will make the battery charge go down.

So unless you are constantly turning the engine on and off, it seems pretty hard to keep the charge level of the battery constant.

 

[efusco]

Further, when your Energy screen battery SOC shows all green...what you perceive as "full" the reality is that the batteries are really only at about 70% of their maximal SOC. Even at that the computer systems will go through many gyrations to prevent you from charging it more fully and will, preferentially, use more battery power than ICE power until it's back in the most 'happy' SOC level (all blue).

Once in a while, say after a long downhill coast to a stop you may get all green on your battery SOC. The ICE will shut down normally, then spin up, shut off, and do that for a varying number of cycles. That is one way the ECU uses up the 'excess' battery charge...it takes quite a bit of energy to 'spin up' the ICE.

 

[zinzindorff9]

The internal engine does constantly start, run, and stop. It can run to charge battery, to provide additional power to "motovate" and to do both at same time. Everything in the Prius is constantly cycling. Two electric motors and one internal combustion engine. (ICE)

 

[unclehan]

What's the energy capacity of the battery?

 

[DaveinOlyWA]

max output is 21kW

storage capacity is about 80-120 amphours (guesstimate based on weight and makeup of traction battery)

actual capacity of the battery is not really relevent since you only use slightly less than half of the total capacity anyways. to preserve battery life, the computer keeps the charge bet 40-80%.

 

[BIF]

... to preserve battery life, the computer keeps the charge bet 40-80%.

If I remember correctly,

"zero bars" on the MFD means that SOC can be 40% or less.
"eight bars" on the MFD means that SOC can be 80% or more.

My car only goes down to two bars when I wait in long lines with the AC on, and never while in motion. The computer always starts the ICE at two bars, so I have never seen it go lower than that.

Likewise, the MFD never goes to 8 bars on my car. I don't drive down any long mountain passes here in Florida, so it's not likely that it ever will get "topped off."

My car typically goes between three and six bars, occasionally flirting with the seventh bar and the pretty "green battery" color. But seven bars only happens two or three times a month, and usually only lasts for a few seconds to about a minute.

So, if I guess that each bar on the MFD is worth roughly 5% of SOC (40% range divided by 8 bars), then it appears that my car generally keeps the battery between 45-50% at the low end, to about 55-60% at the upper end.

That's a range of only 15%.

And that, as John1701a mentioned above, is the reason the batteries last for hundreds of thousands of miles.

 

[dkchin]

Battery Power

max output is 21kW.

I am not so sure about that. Toyota site spec list it as 21kW but it really should be 25kW(34hp). As discussed on Prius-Technical yahoo group, ICE 76hp+HV battery 34hp = 110hp total output. [email protected] pointed out that panasonic module specs show even higher output.

The 21kW number seems to be from the classic battery rating. I called Toyota up and let them know about this but don't know if my message will get through.

Prius GT article confirmed the stock battery can output 25kW.
"To cope with the extra power, the battery has been upgraded to develop 34 kW or 46 DIN hp (a gain of 9 kW / 12 DIN hp)"
http://www.canadiandriver.com/news/040628-4.htm

Dennis

 

[DaveinOlyWA]

you are confusing the max output of the battery verses the max output of the EV maybe?

although the EV is rated at 50 kW max, the total power is not additive.

the battery by itself cannot provide enough to power the EV at max capacity. talk to anyone who has run out of gas and they will tell you that the first thing they noticed was an immediate and significant loss of power.

 

[frenchie]

What's the energy capacity of the battery?

The battery for the 2004 is made of 28 modules, 7.2 V and 6.5 Ah capacity each. That makes 28*(7.2*6.5)=1310 Wh total capacity. However, all the capacity is not used as you probably know. For the Classic the total capacity was about 1.8 kWh (because of 38 modules instead of 28) and people seem to agree that a 40% of this is used, which means about 720 Wh. When the new Prius was launched some Toyota people said that although the total capacity was less, the usable capacity was about the same, which would mean a wider SoC window. I haven't seen however, any "official" Toyota figures...

storage capacity is about 80-120 amphours (guesstimate based on weight and makeup of traction battery)

Wrong. Toyota clearly states it's 6.5 Ah :
http://www.toyota-europe.com/showroom/P ... asp?body=S

 

[DaveinOlyWA]

according to Frank Hudon (he is on Priuschat.com) who owns both a classic and an 04, he says the charge in the classic is much larger and noticable.

he says he can EV much longer in the classic than he can in the 04.

 

[john1701a]

Having driven 60,000 miles in my 2001 and 22,000 miles in my 2004, I can strongly disagree with that claim. I can clearly drive further in stealth now.

I never used to be able to reach the end of the 35 MPH road that I commonly drive without the engine starting for recharging, in my Classic. But with the HSD, I can make it the whole way.

 

[DaveinOlyWA]

well distance you can drive and the rate of power output wouldn't be comparable. they are two different measures of the same thing.

that is like putting 10 gallons of gas in a pinto and 10 gallons in a corvette. the pinto will most likely go farther but the corvette will get there a lot faster. same amount of power either way.

what he was saying is that there is more power under the battery for acceleration in the classic. according to Toyota's website, the battery charge and distribution efficiency for the 04's was increased something like 30% over the classic so it should go further even if the batteries were equal.

 

[john1701a]

what he was saying is that there is more power under the battery for acceleration in the classic.

I disagree with that vague claim too.

Got any details?

 

[ken1784]

what he was saying is that there is more power under the battery for acceleration in the classic.

Toyota says as follows...
http://www.toyota.co.jp/en/tech/environ ... power.html

Regards,
[email protected]

 

[DaveinOlyWA]

im sorry i dont. just relaying info that ive heard. i will be the first to tell you that i know practically nothing about the classics. and other than Frank's, i've never seen one really run before.

to be honest with you, i was surprised that it had a regular key, started and ran like a regular car until it warmed up, etc.

 

[DaveinOlyWA]

ken:

toyota states that the battery power density was increased 35%. that maybe so, but the battery in the 04 is 36% lighter than the classic battery. so you are looking at a nearly break even stat.

as i said, i dont know.

lets go for a better question since battery charge is neither here nor there in the overall scheme of things,

what is the performance numbers for both vehicles in a 0-30 or whatever is available. that would be a better indicator of power although differences in the cars will play a part in the numbers.

i know the 0-60 time in the classic is way slower.

 

[ken1784]

what is the performance numbers for both vehicles in a 0-30 or whatever is available. that would be a better indicator of power although differences in the cars will play a part in the numbers.

i know the 0-60 time in the classic is way slower.

I think the 0-30 MPH time data is not available, but the power of 2004 Prius is always better than classic in all range.

Please refer to...
http://www.toyota.co.jp/en/tech/environ ... utput.html

I would like to recommend you to read through the site from the beginning...
http://www.toyota.co.jp/en/tech/environ ... index.html

Also...
http://john1701a.com/prius/presentation ... ion_01.htm

Regards,
[email protected]

 

[frenchie]

what is the performance numbers for both vehicles in a 0-30 or whatever is available. that would be a better indicator of power although differences in the cars will play a part in the numbers.

i know the 0-60 time in the classic is way slower.

Acceleration times are a good indicator of total power, not battery power. Engine power is much larger at low speeds in the 2004 because of increased rotation speed of MG1 (engine can rev faster).