Is there any facility to charge the battery from an external source? I'm assuming this is not a 'plug-in' hybrid?
The Prius is quite a large car, the thing that concerns me is a 15 year old diesel Mondeo can typically get 55mpg overall, without the complexity of a hybrid.
Not the HV battery. It's 200V DC, and charging it would only allow a couple of miles on electric alone. It's not designed to be an EV, it's an energy buffer. The 12V battery is a regular car battery that can be charged on any charger.
People quoting mpg numbers typically quote them 'on a run', when conventional diesels/petrols are most efficient at motorway speeds. They are less clear what they get running around town.
If all you're doing is motorway driving, buy a diesel. The hybrid makes sense when you do more driving at lower speeds. It's the reason hybrids are so popular as taxis.
Complexity is not really an issue apart from upfront cost - I was looking for a scrap part recently and the scrap Priuses were all 200-300K miles. I presume they just ran until the owners just had enough and they were worth more parted out.
Theo
Shame it's just 2 miles. The average journey is/was 7.
I saw those numbers and some other Mondeo diesels in that site give better numbers. They do seem low to me. Obviously UK mpg is higher than US mpg.
I was going from experience, and mainly rural miles rather than urban, so you certainly have a point. One tank when I was taking it easy I got
65mpg.
I was aware they are popular as taxis, historically well be before the Prius. I recall the Toyota Corolla being a popular taxi.
One of the big advantages for taxi use is regenerative braking. Brake components on EVs and hybrids generally last much longer than ?normal? cars.
Tim
And all the exceptions re congestion charging. ;-)
I would be interested to hear from Theo below what speed the breaking is still mostly mechanical (re urban / motorway driving).
Cheers, T i m
I think you mean ?braking?. I can?t speak for hybrids but on EVs there is no ?speed limit? for regenerative braking. The limits are the rate of deceleration that the motor can produce and the battery capacity. A fully charged EV won?t do regenerative braking as there?s simply nowhere to put the energy.
Tim
I think gen2 Prius regen goes down to about 7-8mph. At that point the amount of braking you can get from the motor alone is limited, and you want it to stop accurately (going 1 metre extra across a pedestrian crossing would not be great). You can feel it's a bit notchy slightly above that speed - as if you can feel the poles of the motor as it rotates - which is a bit disconcerting until you get used to it. Your instinctive reaction is to push the brakes harder which will bring in friction braking anyway.
Unless you're descending hills, on the flat it will keep some headroom in the battery such that there's enough space to capture energy in regen. It'll then use that energy next time you accelerate, so it tries to always have scope to regen. Although the motor isn't large, so if you're less than gentle on the brakes it'll bring in the friction system.
Theo
Yup, I thought it looked wrong. ;-)
Ok.
Well that was the bit I was interested in. If there was a speed below which electric braking wasn't sufficiently effective (above a walking speed I mean).
Understood, although I'm guessing it doesn't take many miles to create some space on a dedicated EV. ;-)
Cheers, T i m
That's lower than I thought but that said, I know all too well how 'heavy' a shorted electric motor can become when trying to push a mobility scooter. ;-)
So it *will* actually bring you to a halt with motor braking alone, noticeable above rolling resistance etc?
Makes sense.
So what does it do when descending hills, assuming you approach the top of one with a fully charged battery? Two questions really:
Does it 'coast' if you don't touch the brake like a car in neutral or 'hang' on the motor / transmission like one in gear but with you foot off the throttle?
What if you apply some (electric) brake that would maintain the same speed but then make the battery fully charged (either really or technically), does it then apply the mechanical brakes on it's own (like an ABS) 'instead' or start coasting faster till you use mechanical brakes?
The motors on the mobility scooters we have seem quite large (by comparison then) and the big one will bring it and me to a halt from full speed (8mph) down a fairly steep slope in a bit over a second. ;-)
Cheers, T i m
OTOH 1+ tonne of car has a lot of KE, even at low speeds. A 20hp motor isn't a lot in comparison.
It won't let you find that out, it brings in the friction below 7mph.
I think it's like a regular auto - it won't brake unless you press the brake pedal. It's not one-pedal driving like some EVs. It's not 'coasting' in the sense of running away due to having the clutch disengaged (the transmission is always engaged - I suppose you could try forcing it into neutral but it would complain mightily). If you take your foot off the accelerator then it's a fight between friction, gravity and momentum as in any other car.
When the battery is full it'll use friction brakes. You can't select what kind of braking it uses, you can only tell by paying close attention to the sounds and the feel. You just use 'the brakes' and it decides how to achieve it.
There is also 'B' mode which provides classical engine braking, in case you're doing a heavy descent and are worried about your friction brakes overheating. I've used it about twice, in neither case did I need it.
I imagine you don't weigh a tonne? :-)
Theo
Understood.
Ah.
Ok.
No, I didn't think the Prius was like that for some reason (I'd consider them more 'traditional' that way).
That was my question. I guessed the transmission would always be engaged and I believe it 'blends' a mix of inputs and outputs (but not disconnects). It was in the overrun situation but with no need for regen charge I was wondering about.
That wasn't my suggestion. ;-)
Quite, where none the 'friction' is introduced, it's whatever present.
So with that, does the pedal have physical travel ranges where it would first only be electrical and then mechanical after that or is the actual braking used linear from the outset (decided by it as you next mention)?
Ok.
The only time I seen that was on a Daf 'Daffodil' and it was like a choke knob that affected the CVT. ;-)
No, but my point was more how effective even a small motor can be as a brake, dependant maybe on the gearing between wheels and motor.
eg, If you do the same thing on a loose surface it will lock one of the (tranaxle / diff) wheels up.
Or when racing slot cars or the 12th scale RC 4WD comp cars where you could also lock the wheels up (well, ABS stylee) under heavy (electrical) braking.
Cheers, T i m
I remember doing a long journey in an early Prius. Due to being rather underpowered, it had to be driven near flat out on the motorway. And used more fuel than my Rover V-8. ;-) But it gave very good MPG in town - I suppose that's why they're so popular as mini-cabs.
[snip]
The high voltage battery can never be fully charged under normal driving. It is only charged to 80% capacity and allowed to discharge to 40%, this preserves the cells. The energy monitor inside the car normally has one bar left.
So when descending a hill with a fully charged i.e. 80% battery, the regenerative braking charges the battery to 100% filling the remaining bar on the energy monitor regardless of the gearbox normal or the additional braking mode.
It takes quite a bit to fill this one bar and I have only seen it happen once in the two years I have driven my Prius generation 3.
The transmission never coasts it is always engaged going down a hill is like a manual car with your foot off the throttle. I hope this answers your questions.
Understood.
Understood.
So it knows there is 40% left but inhibits you using it any further?
Ah, 'additional', so am I right in thinking it would typically include electrical / regenerative braking *and then* mechanical braking under all circumstances? I believe Theo suggested that the mechanical braking can come in quickly if you aren't gentle on the brake but I wasn't sure if it *always* applied both or if there were instances where you just had mechanical only (other than when it was 100% charged etc)?
Nice long down hills where you had to apply some level of braking the whole time?
Understood.
I'm getting a better feel for it all (thanks).
Actually, whilst watching (typically) taxi drivers dropping people off when out walking the dog when it's quiet at night and being fascinated by the 'silence' as these (typically Prius's) waft about, I have suggested to the Mrs we see how much it would cost to hire one for a day, when we have somewhere 'urban' to go?
I am familiar with pure EV's as I have had one for over 30 years, but it's very basic (std mechanical brakes and no regen), not a hybrid and it's those that interest me from these technical / usage POV.
Cheers, T i m
The bars are fiction - they're an indication of the battery status but not a direct measure of it. You can read out the SoC with OBD if you want the actual numbers. I think 'nearly full' at the top of the blue bars which is where it prefers to keep it is something like 66% of SoC and the extra two green bars come up to at about 80%.
If you do regen you can get those green bars to fill up, but it won't do it from the engine out of choice.
I believe it's mech only below 7mph on Gen2. If you emergency stop I don't know what it does with regen, but it stops like any other car.
Way to think of it is that it's basically normal mechanical braking but with regen creaming off energy when it can. If you brake gently you hear the regen, if you drive it heavily the friction will take over.
Not sure about the Gen3 but it's easy on a Gen2 - motorway offslip with nobody behind you so you can brake through it gently down from 70mph. Or on hills, I hear they have them in other parts of the country.
The older ones are easier to work out what's going on. The newer ones have it blended more smoothly so it's harder to tell what it's doing. In general you just drive it like a normal car, there's nothing extra to do.
There's a display that shows what's happening with energy transfer which is useful when you first get it and want to understand what's going on:
Some of the newer ones have this as a prettier display but much less readable when driving:
Theo
Yes and it then starts the petrol engine being a hybrid car.
I'm surprised. I know (from personal experience) it's difficult to accurately indicate the current SOC of a battery but you would have thought that with all the engineering that Toyota obviously put into even the first Prius, it would have a fairly accurate battery gauge?
That makes even less sense then if 'better' information is available but not used?
Ok.
Understood.
Yes, I believe you said.
I guessed it would but I was (only) wondering if the braking role was a direct function of the pedal position / hydraulic pressure in that it went though the 'electric' then 'mechanical' braking no matter how fast / hard you pressed the pedal or if the electric was bypassed (as opposed to not having time to come in) if you did a rapid stop. Not because of the outcome (as you say, it should / would stop like any other car), but the process behind the scenes.
Understood, where the 'taking over' is simply mechanical braking effect out-performing the electric braking effect (both are likely still running in parallel).
Gotcha. So not that long / difficult then?
Apparently.[1] ;-)
I imagined they might be. Not that 'evolution' can not also include 'simplification' but it rarely seems to.
Do you feel they have done that with advanced software or are you aware of significant advances in the drivetrain / rolling gear?
Funnily, that also applies to my old EV, just that there is no engine noise when you turn it 'On'. ;-)
Interesting ta. I might make a replica one with an Arduino to put in the Meriva. ;-)
Why do they do that. ;-(
It looks 'bling' but as you say, probably doesn't convey the information as clearly as the 'old way'.
It was a bit like that with my older Garmin GPS's and the newer one. The newer one is obviously more targeted at 'Consumers' but there was a load more information you could optionally select / display (that probably wouldn't be of interest to 'most people').
I'll see what's about (I'd want to have at least a day driving it 'normally' myself, rather than blagging a test drive etc).
Cheers, T i m
[1] Something you don't necessarily notice till you are on a cycle or driving a pure EV. ;-)On Mon, 07 Jun 2021 20:33:18 +0100, John Bryan snipped-for-privacy@gmail.com wrote: <snip>
Understood (I should have said 'inhibits it using it on battery alone any further' ...).
OOI, is there an 'emergency, take it down to (say) 20% option', (user option, rather than workshop / tech) in case you were out of fuel and wanted to get somewhere safe?
Not that I understand you can go that far on battery alone (especially a depleted one). ;-)
Cheers, T i m
It's not an EV, so it doesn't need to show you accurately how many miles you've got. It's just really three states: 'low, I'm going to start the engine', 'a few levels of normal' and 'high: I've got plenty, thanks'. You don't need to care - when it gets low it'll kick in the engine.
I'm sure there are rules that determine 5 bars is between 42 and 51% SoC or whatever, but you don't need to know them. You also don't care if it says 'empty' or 'full' - 'empty' does not mean 0% and 'full' does not mean
100%.It's the same with laptops and others these days: 0% does not mean the battery is at 0V.
You're overthinking it. You can, and I usually do, drive it with the screen turned off. I don't care what the battery SoC is - it's a car, it worries about that.
No idea - the pedal position goes into the ABS ECU, the comms to the hydraulics and motor ECUs come out. I don't know what that software does.
Each bar is about 50Wh so about half a large laptop. It doesn't take a lot of
0.5mv^2 where m = 1tonne to capture that. In normal town driving you might capture 25-50Wh every 5 minutes. It's more limited by the motor capacity in that you typically need to brake in a short-ish distance.The motors are much more powerful so it's like you have a bigger engine - put your foot down and you get full engine power plus full motor power at the same time. It doesn't last for long (at least on the non-plugin versions with the small batteries) but makes up for the smaller engines. More recent Prius have 1.8 engines over the original 1.5, which is now found in the Yaris. That helps with acceleration and possibly motorway efficiency as it's not running quite as hard.
I'm sure there's some fun to be had with writing a fake display app for Android Auto or Carplay. On that note, I should try this one:
Forgot to mention, the Aygo still has a miserable 'X-shift' computer-clutch that everyone else abandoned a decade ago. So if you hire and get a small auto you might end up with that. All the other auto 'normal cars' in the current range should be OK.
Theo
Ah, good point (my baseline is EV's / battery powered stuff etc).
Cool. ;-)
Quite. It's those AFAYAC.
Sure.
Understood.
I didn't think you would specifically, just you might be aware of the higher level processes involved (beyond what you may have mentioned so far)?
But if in 'electric mode' that wouldn't be a net gain (less the journey was downhill). ;-)
Understood.
Quite. Similar to 'load shedding' (disconnecting the output of the alternator) on std IC cars.
I wonder what the sweet spot is and (so) if they will come out with a different size?
When buying a new (company) Sierra Estate you could get 1.3, 1.6, 2.0 and a 2.3 (might have been diesel) but ignoring the diesel if it was, the 2l (from memory) offered the best 'all round' MPG, especially if you were doing a fair bit of motorway work.
Don't know those.
I would if I had a Prius. That's why I have OpComm and Forscan. ;-)
Yeah, or to get a better understanding of what's going on. I like the 'Heads up display' on Torque. ;-)
Ah. ;-(
I think I will specifically look for a Prius as they sorta set the scene at the beginning?
Cheers, T i m
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