Battery size vs. power from MG
#1
Instructor
Thread Starter
Battery size vs. power from MG
The nerd in me got to thinking this morning about various hybrid batteries out there in the market and couldn't figure what 1) battery capacity is vs 2) electric motor power rating.
1) my 2013 450h has 37 kw battery capacity. I think this means amount of power stored.
2) MG2 is rated at 116 kw and MGR(rear) is rated at max output of 50kw.
What I don't get is: How does the 37 kw get used over time???? is this kilowatt per hour? does that pump out all 37 kw in 2 seconds and done with it? how sustainable is that 37kw before we need to go to regen mode? And why do we have a 116kw motor when we don't have 116kw electricity available anywhere???
1) my 2013 450h has 37 kw battery capacity. I think this means amount of power stored.
2) MG2 is rated at 116 kw and MGR(rear) is rated at max output of 50kw.
What I don't get is: How does the 37 kw get used over time???? is this kilowatt per hour? does that pump out all 37 kw in 2 seconds and done with it? how sustainable is that 37kw before we need to go to regen mode? And why do we have a 116kw motor when we don't have 116kw electricity available anywhere???
#2
Instructor
Thread Starter
Some more information from Mercedes Benz hybrid GLE (as a comparison)
its battery is 9 kwh (note the "per hour" figure) in capacity and the electric motor's max output is 85kw (note the absence of "h") in there. How in the world is the 9kwh battery gonna power the 85kw motor????
its battery is 9 kwh (note the "per hour" figure) in capacity and the electric motor's max output is 85kw (note the absence of "h") in there. How in the world is the 9kwh battery gonna power the 85kw motor????
#3
Moderator
Some more information from Mercedes Benz hybrid GLE (as a comparison)
its battery is 9 kwh (note the "per hour" figure) in capacity and the electric motor's max output is 85kw (note the absence of "h") in there. How in the world is the 9kwh battery gonna power the 85kw motor????
its battery is 9 kwh (note the "per hour" figure) in capacity and the electric motor's max output is 85kw (note the absence of "h") in there. How in the world is the 9kwh battery gonna power the 85kw motor????
For simplicity lets assume there is no loss [there is always a loss of energy, but for now lets assume there is none].
Amount of energy stored in battery [9kwh] is 9K watts that can be sustained for 1 hour before being depleted [assuming no charge is done. There is another leap that I am making here that the chemical reaction is no longer regenerating energy .. treating the situation as a large Capacitor]
Motor can produce a max of 85K watts ... [once again assuming no loss it can consume 85Kwatts to produce 86Kwatts of turning power]
Now assume you mate the above battery with the above motor you can produce 86Kwatts for 9/86 hrs ~ 1/9.6 hrs.
Seems like a short time, but realistically you do not put the demand on the motor to produce max power. The sustained current most likely will not be supported by the actual wires. What is being quoted is the actual max specs.
Salim
#4
I've only had my 2010 RX450h for six months, but as an engineer I've looked at lots of YouTube videos in order to try to understand the brilliant Toyota hybrid system.
In short, it's much more complicated than one would first think. I don't think of it as an "electric" car, but rather a gas-engined car that maximizes the efficiency of that gas engine. The HV battery is not meant to drive the car along, but rather to provide instant (unnoticeable) engine starts (dozens or hundreds in a typical trip) and to accommodate regen braking. I imagine Toyota experimented with various battery sizes and picked the one that was the best balance of cost, weight, performance, and life. Similarly they probably sized the MG2 motor based on different criteria. MG1 and MG2 are both motors AND generators, and the computer blends their operation with the operation of the gas engine to deliver transparent power--and combines all that with a CVT-style "transmission" effect. Remarkable.
In short, it's much more complicated than one would first think. I don't think of it as an "electric" car, but rather a gas-engined car that maximizes the efficiency of that gas engine. The HV battery is not meant to drive the car along, but rather to provide instant (unnoticeable) engine starts (dozens or hundreds in a typical trip) and to accommodate regen braking. I imagine Toyota experimented with various battery sizes and picked the one that was the best balance of cost, weight, performance, and life. Similarly they probably sized the MG2 motor based on different criteria. MG1 and MG2 are both motors AND generators, and the computer blends their operation with the operation of the gas engine to deliver transparent power--and combines all that with a CVT-style "transmission" effect. Remarkable.
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vlad_a (05-18-17)
#6
Sorry, what I mean is that the electric system is not meant to "primarily" power the car. All the energy moving the car comes ultimately from combustion of fuel in the engine. All the supporting stuff is designed to help that engine run in its most efficient mode. A full-throttle start uses both the engine and the stored electical energy, but that maximum effort can't be sustained, nor was it meant to be. By contrast a plug-in or EV car assumes that most or all of the required energy comes from the mains.
As for the CVT effect, the hybrid does not use a conventional cone-and-belt mechanism. Instead, both the engine and the Motor-Generator are on a planetary gearset, and the Motor-Generator is driven in such a manner that the engine runs at an rpm appropriate for the amount of power needed at that moment. Very clever. And no belt to wear out, it's just a planetary gearset.
As for the CVT effect, the hybrid does not use a conventional cone-and-belt mechanism. Instead, both the engine and the Motor-Generator are on a planetary gearset, and the Motor-Generator is driven in such a manner that the engine runs at an rpm appropriate for the amount of power needed at that moment. Very clever. And no belt to wear out, it's just a planetary gearset.
Last edited by riredale; 05-06-17 at 01:03 PM.
#7
Moderator
Sorry, what I mean is that the electric system is not meant to "primarily" power the car. All the energy moving the car comes ultimately from combustion of fuel in the engine. All the supporting stuff is designed to help that engine run in its most efficient mode. A full-throttle start uses both the engine and the stored electical energy, but that maximum effort can't be sustained, nor was it meant to be. By contrast a plug-in or EV car assumes that most or all of the required energy comes from the mains.
As for the CVT effect, the hybrid does not use a conventional cone-and-belt mechanism. Instead, both the engine and the Motor-Generator is on a planetary gearset, and the Motor-Generator is driven in such a manner that the engine runs at an rpm appropriate for the amount of power needed at that moment. Very clever. And no belt to wear out, it's just a planetary gearset.
As for the CVT effect, the hybrid does not use a conventional cone-and-belt mechanism. Instead, both the engine and the Motor-Generator is on a planetary gearset, and the Motor-Generator is driven in such a manner that the engine runs at an rpm appropriate for the amount of power needed at that moment. Very clever. And no belt to wear out, it's just a planetary gearset.
Salim
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#8
Instructor
Thread Starter
then, what does this mean:
Hyundai Sonata Plug-in only has 9.8 Kwh battery - seems very small, with an MG producing 50 kw of power only. Yet, this can go so far without gas as well as to produce pretty good 0 to 60 times. Something doesn't sound right. Our EV range is pretty much parking lot only...... yet, our battery and MGs aer much bigger....
Hyundai Sonata Plug-in only has 9.8 Kwh battery - seems very small, with an MG producing 50 kw of power only. Yet, this can go so far without gas as well as to produce pretty good 0 to 60 times. Something doesn't sound right. Our EV range is pretty much parking lot only...... yet, our battery and MGs aer much bigger....
#9
Racer
then, what does this mean:
Hyundai Sonata Plug-in only has 9.8 Kwh battery - seems very small, with an MG producing 50 kw of power only. Yet, this can go so far without gas as well as to produce pretty good 0 to 60 times. Something doesn't sound right. Our EV range is pretty much parking lot only...... yet, our battery and MGs aer much bigger....
Hyundai Sonata Plug-in only has 9.8 Kwh battery - seems very small, with an MG producing 50 kw of power only. Yet, this can go so far without gas as well as to produce pretty good 0 to 60 times. Something doesn't sound right. Our EV range is pretty much parking lot only...... yet, our battery and MGs aer much bigger....
#12
Instructor
Thread Starter
1.9kwh is not that much. I wonder how other cars have so much more energy stored in them. and more importantly, why Lexus can't have as much battery capacity like that of the Sonata. in fact, I think our batteries are actually bigger (physically)
#14
Lead Lap
You can get approx 50 HP* out of the battery to drive one or both (or three, if AWD) of the motors, afterwhich the ICE is called upon to provide power to the wheels via MG1 (using up to approx 25% of the ICE as a generator) plus up to approximately 75% of the torque to the wheels from the ICE.
The planetary gears of the eCVT are approximately 25% to MG1; and approximately 75% (78%, IIRC) to the engine.
Depending upon the programming, the driver's input, and the alignment of Neptune with The Moon, the mix of electricity from the battery, MG1, MG2, the ICE, and even the motor in the rear of the AWD motor contribute to forward propulsion of the vehicle at any given time.
It's simply a bit shy of magic.
*37 Kw converts to 49.6 HP
The planetary gears of the eCVT are approximately 25% to MG1; and approximately 75% (78%, IIRC) to the engine.
Depending upon the programming, the driver's input, and the alignment of Neptune with The Moon, the mix of electricity from the battery, MG1, MG2, the ICE, and even the motor in the rear of the AWD motor contribute to forward propulsion of the vehicle at any given time.
It's simply a bit shy of magic.
*37 Kw converts to 49.6 HP
Last edited by NateJG; 05-24-17 at 09:34 AM.
#15
Lead Lap