T i m wrote:
On Mon, 07 Jun 2021 15:12:11 +0100, John Bryan
wrote:
The energy monitor inside the car normally has one bar left.

So it knows there is 40% left but inhibits you using it any further?

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.

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)?

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.

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.

Nice long down hills where you had to apply some level of braking the
whole time?

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.

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.

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:
http://john1701a.com/prius/prius-how.htm
('Classic' is a Gen1, 'Iconic' a G2)

Some of the newer ones have this as a prettier display but much less
readable when driving:
https://car-images.bauersecure.com/p...taprius_91.jpg

I think other Toyota hybrids have a similar screen, possibly more hidden in
the entertainment system. Almost all new Toyota autos are hybrids these
days (apart from the diesels and the sports cars), so probably wouldn't be
too difficult to hire one.

Theo

In message
T i m wrote:

On Mon, 07 Jun 2021 15:12:11 +0100, John Bryan
wrote:


[snip]

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?

[snip]

The high voltage battery can never be fully charged under normal driving.

Understood.

It is only charged to 80% capacity and allowed to discharge to 40%, this
preserves the cells.

Understood.

The energy monitor inside the car normally has one bar left.

So it knows there is 40% left but inhibits you using it any further?

Yes and it then starts the petrol engine being a hybrid car.

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.

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)?

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.

Nice long down hills where you had to apply some level of braking the
whole time?

The transmission never coasts it is always engaged going down a hill is
like a manual car with your foot off the throttle.

Understood.

I hope this answers your questions.

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


--
John Bryan

On 07 Jun 2021 18:14:31 +0100 (BST), Theo
wrote:

T i m wrote:
On Mon, 07 Jun 2021 15:12:11 +0100, John Bryan
wrote:
The energy monitor inside the car normally has one bar left.

So it knows there is 40% left but inhibits you using it any further?

The bars are fiction - they're an indication of the battery status but not a
direct measure of it.

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?

You can read out the SoC with OBD if you want the
actual numbers.

That makes even less sense then if 'better' information is available
but not used?

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%.

Ok.

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.

Understood.

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)?

I believe it's mech only below 7mph on Gen2.

Yes, I believe you said.

If you emergency stop I don't
know what it does with regen, but it stops like any other car.

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.

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.

Understood, where the 'taking over' is simply mechanical braking
effect out-performing the electric braking effect (both are likely
still running in parallel).

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.

Nice long down hills where you had to apply some level of braking the
whole time?

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.

Gotcha. So not that long / difficult then?

Or on
hills, I hear they have them in other parts of the country.

Apparently.[1] ;-)

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.

The older ones are easier to work out what's going on.

I imagined they might be. Not that 'evolution' can not also include
'simplification' but it rarely seems to.

The newer ones have
it blended more smoothly so it's harder to tell what it's doing.

Do you feel they have done that with advanced software or are you
aware of significant advances in the drivetrain / rolling gear?

In general
you just drive it like a normal car, there's nothing extra to do.

Funnily, that also applies to my old EV, just that there is no engine
noise when you turn it 'On'. ;-)

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:
http://john1701a.com/prius/prius-how.htm
('Classic' is a Gen1, 'Iconic' a G2)

Interesting ta. I might make a replica one with an Arduino to put in
the Meriva. ;-)

Some of the newer ones have this as a prettier display but much less
readable when driving:
https://car-images.bauersecure.com/p...taprius_91.jpg

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 think other Toyota hybrids have a similar screen, possibly more hidden in
the entertainment system. Almost all new Toyota autos are hybrids these
days (apart from the diesels and the sports cars), so probably wouldn't be
too difficult to hire one.

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
wrote:
snip

It is only charged to 80% capacity and allowed to discharge to 40%, this
preserves the cells.

Understood.

The energy monitor inside the car normally has one bar left.

So it knows there is 40% left but inhibits you using it any further?

Yes and it then starts the petrol engine being a hybrid car.

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

T i m wrote:
On 07 Jun 2021 18:14:31 +0100 (BST), Theo
wrote:

The bars are fiction - they're an indication of the battery status but not a
direct measure of it.

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?

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 can read out the SoC with OBD if you want the
actual numbers.

That makes even less sense then if 'better' information is available
but not used?

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.

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.

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.

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.

Gotcha. So not that long / difficult then?

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 newer ones have
it blended more smoothly so it's harder to tell what it's doing.

Do you feel they have done that with advanced software or are you
aware of significant advances in the drivetrain / rolling gear?

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.

Interesting ta. I might make a replica one with an Arduino to put in
the Meriva. ;-)

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:

https://play.google.com/store/apps/d...l.app&hl=en_GB

(I tried an app called PriiDash on a Windows tablet - gave me lots of stats
which were nice but ultimately distracting. Only worth doing if something is
broken really)

I think other Toyota hybrids have a similar screen, possibly more hidden in
the entertainment system. Almost all new Toyota autos are hybrids these
days (apart from the diesels and the sports cars), so probably wouldn't be
too difficult to hire one.

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).

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

On 07 Jun 2021 21:39:58 +0100 (BST), Theo
wrote:

T i m wrote:
On 07 Jun 2021 18:14:31 +0100 (BST), Theo
wrote:

The bars are fiction - they're an indication of the battery status but not a
direct measure of it.

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?

It's not an EV, so it doesn't need to show you accurately how many miles
you've got.

Ah, good point (my baseline is EV's / battery powered stuff etc).

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.

Cool. ;-)

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%.

Quite. It's those AFAYAC.

It's the same with laptops and others these days: 0% does not mean
the battery is at 0V.

Sure.

You can read out the SoC with OBD if you want the
actual numbers.

That makes even less sense then if 'better' information is available
but not used?

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.

Understood.

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.

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.

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)?

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.

Gotcha. So not that long / difficult then?

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.

But if in 'electric mode' that wouldn't be a net gain (less the
journey was downhill). ;-)

It's more limited by the motor capacity in
that you typically need to brake in a short-ish distance.

Understood.

The newer ones have
it blended more smoothly so it's harder to tell what it's doing.

Do you feel they have done that with advanced software or are you
aware of significant advances in the drivetrain / rolling gear?

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.

Quite. Similar to 'load shedding' (disconnecting the output of the
alternator) on std IC cars.

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 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.

Interesting ta. I might make a replica one with an Arduino to put in
the Meriva. ;-)

I'm sure there's some fun to be had with writing a fake display app for
Android Auto or Carplay.

Don't know those.

On that note, I should try this one:

https://play.google.com/store/apps/d...l.app&hl=en_GB

I would if I had a Prius. That's why I have OpComm and Forscan. ;-)

(I tried an app called PriiDash on a Windows tablet - gave me lots of stats
which were nice but ultimately distracting. Only worth doing if something is
broken really)

Yeah, or to get a better understanding of what's going on. I like the
'Heads up display' on Torque. ;-)

I think other Toyota hybrids have a similar screen, possibly more hidden in
the entertainment system. Almost all new Toyota autos are hybrids these
days (apart from the diesels and the sports cars), so probably wouldn't be
too difficult to hire one.

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).

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.

Ah. ;-(

All the other auto 'normal cars' in the
current range should be OK.

I think I will specifically look for a Prius as they sorta set the
scene at the beginning?

Cheers, T i m

T i m wrote:
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?

There's an EV mode button. You can press that and it won't start the engine
when you start driving. Eventually it will when the battery gets low. You
aren't supposed to run it without fuel in - I don't know what happens if it
can't start it. Possibly you can force it to limp a bit further somehow, I
don't know.

Theo