Braking best techniques

[Melinda]

I just got a C-Max and want to get clearer on best driving practices.  I am tapping the brake as I slow to a stop, betting as much regen time as I can. I am accelerating slowly and stopping gradually.  Is this the idea?

[Jus-A-CMax]

That's a great start, and WELCOME to the forum :)

 

I know you have a TON of questions you would like to ask but may I suggest you peruse this forum and the sub-sections. Most of the useful threads like tips & techniques are pinned (on top) of the sections and there is always a search function here. Have a look at the links in my signature as well.

 

One thing to always keep in mind as a new hybrid driver:

 

1. Be patient with yourself, none of us were born with MPGs in our brains.

 

2. Stick to the right and be courteous to the driver behind you - that is - don't go turtle slow if there is traffic behind you. Go with the flow of traffic. Theres plenty of roads to save the MPG later on.

 

 

If I were you, drive the CMax like a regular car for 2 tanks before worrying about getting the MPGs since it will take some time to get to know the battery & brakes and how the moves & glides.

 

Jus have fun for now, ok ;)

 

ps in the meantime, hang around this forum and check out the many, many cool threads & posts :rockon:

[C-MaxSea]

Welcome Melinda !  Jus's advice is golden - have fun and be patient. 

 

Yes take it easy on the brakes and you will see the brake scores reflect good 'MPG braking' (storing energy in the hybrid battery). 

 

Acceleration is a bit more challenging, a little bit of EV followed by a more aggressive ICE burst, then tracking at speed limits with as little use of gas as possible.

 

That is a crude overview, but Jus's posts and others will be helpful as you get past your 'just have fun' break-in phase.

 

Enjoy,

 

Nick

 

(PS  Get rid of those leaves and put something on that screen more useful to you)

[fotomoto]

In the left screen settings menu, make sure "Brake Coach" is enabled and strive for 100% scores.  It's a great learning tool/aid.

[joe]

Melinda - You indicated that you "tap" the brakes.  I would suggest "riding" the brakes gently when slowing up. 

 

In regards to acclerating, you should speed up to the speed limit using the gas engine rather than starting slowly and using the battery.  Why?   High mpg comes from covering more ground using electric than gasoline.  When accelerating to the speed limit, it might take a quarter mile to get up to the speed limit.  If you use electric to cover the quarter mile, it drains the battery and forces the C-Max to switch to gasoline when you get up to speed.  Whereas, if you use gasoline for the first quarter mile to get up to the speed limit, it results in having electric power to cover the next half mile or mile on electric at the speed limit. This will give you better mileage.  It took me months to figure this out.

[mtb9153]

It is vitally important to brake slowly and gradual as you approach a light or stop sign.  Abrupt braking will really cut into your AvMPG and braking scores.  I always try to start braking early with a light but even pressure on the pedal when coming to a stop.

[mtb9153]

Melinda - You indicated that you "tap" the brakes.  I would suggest "riding" the brakes gently when slowing up. 

 

In regards to acclerating, you should speed up to the speed limit using the gas engine rather than starting slowly and using the battery.  Why?   High mpg comes from covering more ground using electric than gasoline.  When accelerating to the speed limit, it might take a quarter mile to get up to the speed limit.  If you use electric to cover the quarter mile, it drains the battery and forces the C-Max to switch to gasoline when you get up to speed.  Whereas, if you use gasoline for the first quarter mile to get up to the speed limit, it results in having electric power to cover the next half mile or mile on electric at the speed limit. This will give you better mileage.  It took me months to figure this out.

Joe this is still something I haven't quite mastered, I find myself pulling out slowly and trying to keep the ICE from coming on.  Thanks for the tip.

[wab]

I probably got a ZERO brake score this morning.

But hay now I do KNOW the ABS works. Someone :drop: pulled out RIGHT in front of me, we got stopped with barely a foot between us.

 

[fbov]

The old metaphor is to imagine an egg under your foot - then don't break the egg!

 

Enable Brake Coach, so you have feedback

then find the "near 100%" point

then apply the brakes at the "near 100%" level as soon as you see a stop coming, modulating up or down so you stop where you want

 

Set the left screen to "Empower" display, so you have feedback

 then find the "still charging" point when running ICE (battery has a "hat" or "^" above it)

use ICE at the "still charging" point whenever possible; EV if less is needed, hybrid (ICE+EV) when more is needed

 

The trick is to use ICE under high load, when it's most efficient in converting gas into energy, then store the energy as motion, height or battery charge.

It looks something like this:

 

Have fun,

Frank

Edited April 28, 2014 by fbov

[fotomoto]

I probably got a ZERO brake score this morning.

But hay now I do KNOW the ABS works. Someone :drop: pulled out RIGHT in front of me, we got stopped with barely a foot between us.

 

I couldn't score a zero even with full ABS actuation from 70+ mph.  This is the lowest I got after several attempts:

 

[fbov]

foto, you're nuts, but I love you!

 

Regen should always be active. After all, it's the same as engine braking with a manual tranny, sans idle, and with a reservoir to store the energy. Given the seat of my pants tells me we regen-brake at less than 0.1g, 9% seems reasonable.

 

Have fun,

Frank

[plus 3 golfer]

Welcome Melinda.  Practice, practice, practice and you will achieve 100% brake scores anytime you want to (but for an "unplanned" traffic light change). :)  I have always tried to "time" traffic lights and coast to stops as using ones friction brakes in conventional cars wastes energy. I do the same in the C-Max (time lights) to lessen the chance of getting a lower brake score.   Also, become familiar with the "grade assist" button as it can be used when going down hills to maintain speed (so car does not begin to accelerate and pick up speed). Grade assist will first use up to maximum regenerative braking and then use engine braking to maintain ones speed going downhill.  But if speed continues to increase, you can always use the brakes to engage friction braking.

 

Okay, so it looks like fotomoto is the guy to beat.   So, what's the prize for the lowest brake score?  Just some thoughts below on how one might minimize ones brake score.

 

Probably need the HVB full (go down a steep hill to full charge the HVB) and then slam on the brakes to achieve a near zero brake score.  Otherwise, if there is HVB storage space available and since the traction motor MG2 is always spinning when the car is in motion, one would think the traction motor should be charging as one is slowing even under full ABS activation as ABS should not allow the wheels to lock up. Even with a full HVB, one might not be able to get to zero brake score as there will always be load on the car when running that needs supplied and the PCM will likely regulate the operation of MG2 to meet the load (sum of  HV power interfaces = zero) when the HVB is full.  

 

Also, does one want to be going fast or slow when trying to achieve a zero brake score assuming brake score is a % of the energy captured to the available energy that could be captured. Since vehicle load (watts) should be virtually constant during the braking, the energy would simply be load * time.  The time to stop will be a function of the kinetic energy at the time of brake application and maybe potential energy if the ground is not flat once one starts the braking. One would also have to account for the drag (aero and rolling resistance) on the moving vehicle as it is slowing down and the ABS brake load such that the wheels don't lock up.  Any volunteers to come up with the equations that tie all this together or to run tests :)  

[SnowStorm]

The old metaphor is to imagine an egg under your foot - then don't break the egg!

 

I keep an egg on the brake but not always on the gas!  The C-Max is too much fun to never "step on it" now and then!  Its gotten so bad I'm actually happy to see a slow car on a two lane road so I have an "excuse" to gun it! :shift:  And at a 31,000+ lifetime mileage of 46.8 MPG it can't hurt that much!  At risk of considerable repetition, here's my tips for new hybrid drivers.

1. Don't Drag.  Accelerate moderately.  No need to be a slow poke - just don't "floor it" all the time. (And don't worry about the battery!  It will take care of itself.)
2. Don't Speed.  For speed limits of 60 and above, keep to the limit (or below) when practical.  I often drive 65 in 70 zones if traffic allows (not usually in a hurry).
3. Plan Ahead.  Get off the gas early ("coast" awhile) then brake gently for intersections and stops.  I say any "score" above 90% is great.
4. Cruise.  If you can do it safely, use cruise control as much as possible (it works down to 20 mph).  You can also use Eco cruise for gentle, smooth acceleration.  Accelerate manually to 20 mph then tap Resume and the car will go back to the set speed beautifully.  I love it. 
5. No Goosebumps.  Go easy on the A/C.  Use recirculate.  Close unused vents (including back seat).  If by yourself, direct center passenger vent to driver and close the other one (at passenger door).  Set temperature as high as possible and turn up the fan a bit more.  In the end of course, suit yourself.  We're all different (and so is our weather).
6. Drive In Fair Weather!  OK, I'm mostly joking but don't be surprised to see head winds, precipitation and cold dropping your mileage.  It takes a toll on all cars but it seems worse in hybrids since they start with such high MPG numbers.
7. Be Safe.  Don't do anything that jeopardizes safety.  However, I think that developing the "hybrid habits" will make you a better driver overall.  The unsafe crazy, speeding, lane changing maniacs get the worst mileage!
8. Have Fun.  Practice hybrid driving and don't worry about the car or battery.  It will be a long time before you can outsmart the car (except for watching the road ahead!).

[ScubaDadMiami]

There are basic techniques, and then there are more advanced techniques for things. Don't get frustrated by trying the advanced moves from the start.

 

A good acceleration basic is to use EV to between 10-18 mph, ICE at between 1.75 and 2 bars until you get up to speed (or just above), and then to cruise for as long as you can in EV--perhaps slowly losing speed down to your next ICE burn. There are variations that depend on things like battery state of charge, intended speed, etc., but don't worry about those for a while. Just get your basics with something akin to this.

 

For braking, the ideal is to glide to a stop without using the brakes. Since that won't work well with traffic on your tail, try to work things out to brake in a short enough distance not to get people behind you upset while also not waiting until the last second to slam on the brakes. As long as you can apply the brakes evenly from the time that you start to press down on the pedal (you can press a little harder as you near your stop point), you should be getting mostly 100 percent scores, or pretty close to that. There will always be sudden requirements to stop due to road conditions, but you will find, after a while, that you can keep your average at about 98 percent.

Edited April 29, 2014 by ScubaDadMiami

[mtb9153]

My average is far from 98 percent.  I don't know if it's just me but I find it very hard to land a100 percent more than 3 times in a row.  Traffic patterns here in the sillycorn valley are just too unpredictable to maintain a pattern.  My braking score is pretty up and down and why my AvMPG never has gone beyond 58 and that wasn't for long.  Would be nice to get a 700mile tank, but I think I'll have to settle for the 600+ I earned last summer.  But I can dream of better MPG this summer. :future:

[mtcmax]

Really enjoy how the  brake coach helps me be a better driver.. I now look at my driving before the c max as being very crude. 

[fbov]

 

I keep an egg on the brake but not always on the gas!  ...

 

You may want to review the late Dick Turner's autocrossing videos... the egg is attached to your foot, regardless the pedal it's actuating. This, and learning to look ahead (12 sec. per Roger Johnson) were the critical skills of the autocrosser that translate directly to street driving.

 

Any top endurance racer already knows how to drive a hybrid...

 

Have fun,

Frank

[mtb9153]

I probably got a ZERO brake score this morning.

But hay now I do KNOW the ABS works. Someone :drop: pulled out RIGHT in front of me, we got stopped with barely a foot between us.

been there done that, I have severely tested the ABS system on Maxus on multiple occasions.  That pulsing brake pedal is weird but it is working.

Edited April 30, 2014 by mtb9153

[wab]

:headspin:

I probably got a ZERO brake score this morning.

But hay now I do KNOW the ABS works. Someone :drop: pulled out RIGHT in front of me, we got stopped with barely a foot between us.

 

 

You may want to review the late Dick Turner's autocrossing videos... the egg is attached to your foot, regardless the pedal it's actuating. This, and learning to look ahead (12 sec. per Roger Johnson) were the critical skills of the autocrosser that translate directly to street driving.

 

Any top endurance racer already knows how to drive a hybrid...

 

Have fun,

Frank

 

 

been there done that, I have severely tested the ABS system on Maxus on multiple occasions.  That pulsing brake pedal is weird but it is working.

 

If I hadn't been looking/thinking 12 seconds down the road I would have TBONED her.

The car in front of me made a right turn (blocking me to the right) and THERE SHE was,

but I had already seen her, lifted and had my foot on the brake.

 

I asked a co worker, after I thought she was going to kill us, how far down the street she looked?

She looked/thought a few seconds and said "2 or 3 stripes"... I suggested she start looking 4 or 5 :headspin:.
 

[C-MaxSea]

 

".............and at a 31,000+ lifetime mileage of 46.8 MPG .............................

 

 

A big :hat_tip: on those miles and MPG's SnowStorm !

 

Oh, and number 6 works great for me also, especially with a tail wind. :secret:

 

Having fun,

 

Nick

Edited May 1, 2014 by C-MaxSea

[fbov]

30 mph is 44 feet per second. We tend to think 30 is slow, and it is, but it's instructive.

 

12 seconds at 44 ft. per sec. is 528 feet, 1.75 football fields. At 60 mph, it's half that distance, but still a lot farther than you think. And remember, this was an autocross technique, intended for use at speeds in the 30-70 mph range, right where we do most of our driving.

 

Have fun,

Frank

[Noah Harbinger]

The brake coach kind of sucks, but I assume that's intentional - they don't want you focusing on the display when you're braking because the fact that you're braking probably means there's some hazard or limit in front of you. 

 

That said, you would be surprised how hard you can brake and still capture 95-100% of energy. The catch is that the more rapidly you apply braking pressure, the more of the braking will be done by the friction brakes (i.e. WASTE!). So you have to press the peddle extremely evenly. 

 

I would love it if anyone knows more about how the braking system proportions force between the regenerative braking and the friction brakes. 

[marshtex2]

After decades of driving so as to minimize using brakes, I have abandoned trying to change to a style that maximizes dragging the brakes and don't notice a change in actual mpg.  Anyone else have mental trouble joining the brake dragging club?

[Jus-A-CMax]

Brake coach, acceleration coach and whatever-I-forgot-coach is useless, imo. It's not all about braking, if anything is LESS about braking as I get attrocious scores in the LUNATIC Los Angeles City driving and yet I can pull 60-65MPG driving daily in real traffic conditions as I go back and forth from home to work and wherever I care to go in my banged-up-Lemon Maxine.

 

Learn and read the roads better, if you want your MPG. Read the traffic lights, plan ahead but becareful of the red lights - not worth it. Watch the rear traffic....so a road less travelled is an MPG saver. A road with downward incline and a road with the least upward incline (at the expense of additional distance) are preferred options.

 

Remember, MPG is at the expense of time.

Edited May 4, 2014 by Jus-A-CMax

[plus 3 golfer]

After decades of driving so as to minimize using brakes, I have abandoned trying to change to a style that maximizes dragging the brakes and don't notice a change in actual mpg.  Anyone else have mental trouble joining the brake dragging club?

Why do you want to abandon such? Are you saying you downshifted to slow down or coasted to minimize braking? If you've got the time, coasting is better than using brakes. In the C-Max when you coast, there will be regeneration to simulate ICE engine braking as would be the case in non-hybrid cars but not in the C-Max powertrain. Using the brakes increases regeneration and slows the car down faster than coasting but there's energy losses in MG2, inverter, HVB when both storing and using the captured braking energy.