B-mode musings.....

[BoHenriksson]

Well, a few weeks in to ownership I'm trying to pick up some of the finer points of the Leaf experience:

I'm not quite sure about the B-mode. Having driven a 2006 Prius for 100 K plus miles (and consistently achieved MUCH better than sticker mpg) I assumed the Leaf worked the same way. Hitting the brake pedal just engages re-gen, progressively more as you push harder - up to a point of hard braking where the mechanicals kick in for safety. (Also below 7 mph I think). At least that's what I've been led to believe.

Now from reading the various threads here I understand that pushing the brake pedal lightly engages the mechanical brake even initially and somehow blends that with increasing re-gen the harder you push. So, there is some amount of energy wasted! That certainly explains the presence of the B-mode (also, of course, useful on long downhills).

The problem is that driving the Leaf in ECO and normal D-mode is very much like the Prius I've known and loved. I am already pretty much somewhat of a hyper miler and I find it much, much more comfortable than being in ECO+B!
So I guess my question is how much under real life conditions being in B really saves.

I would like to be very efficient (is why we have the Leaf, right?), but not to the exclusion of driving pleasure!

Bo

 

[Boomer23]

I'd say that use of B mode is situational based on what kind of driving you are doing. The following is my opinion, informed by way too much reading in this forum.

For high speed freeway cruising without much stop-and-go, you will do better in D, with or without ECO. This is because gliding and coasting will carry your momentum best, which is more economical than using regen because regen is inefficient.

For city driving with stop signs, traffic lights or freeway/highway with lots of stop and go, B mode will be helpful for the reason you stated, minimizing friction braking until it is needed in the last stage of stopping. The key is that you need to learn to modulate the throttle to avoid invoking regen when you just want to coast. The arc of power "bubbles" above the speedo is useful for easily telling when you are at zero power use but not into regen.

I've found that B mode is the most useful for aggressive "fun" driving, when it behaves likes engine braking as you let off the throttle, slowing you in preparation for a corner.

But I also use it in suburban driving depending on how much stop-and-go I'm doing. If the traffic is running freely, I might select D mode to enable better gliding, but then switch into B when a light turns red ahead and I know that I'll be stopping, in order to get as much regen as possible without invoking friction braking.

 

[hyperlexis]

I'd say that use of B mode is situational based on what kind of driving you are doing. The following is my opinion, informed by way too much reading in this forum.

For high speed freeway cruising without much stop-and-go, you will do better in D, with or without ECO. This is because gliding and coasting will carry your momentum best, which is more economical than using regen because regen is inefficient.

For city driving with stop signs, traffic lights or freeway/highway with lots of stop and go, B mode will be helpful for the reason you stated, minimizing friction braking until it is needed in the last stage of stopping. The key is that you need to learn to modulate the throttle to avoid invoking regen when you just want to coast. The arc of power "bubbles" above the speedo is useful for easily telling when you are at zero power use but not into regen.

I've found that B mode is the most useful for aggressive "fun" driving, when it behaves likes engine braking as you let off the throttle, slowing you in preparation for a corner.

But I also use it in suburban driving depending on how much stop-and-go I'm doing. If the traffic is running freely, I might select D mode to enable better gliding, but then switch into B when a light turns red ahead and I know that I'll be stopping, in order to get as much regen as possible without invoking friction braking.

Does B mode actually work if you have a full or near full battery? Is the engine braking effect increased as the battery drains or does the Leaf always seem to respond the same no matter the state of charge?

 

[Nubo]

Does B mode actually work if you have a full or near full battery? Is the engine braking effect increased as the battery drains or does the Leaf always seem to respond the same no matter the state of charge?

Regen is diminished or curtailed depending on battery SOC and temperature. Overcharging the battery has to be avoided, and there's no other mechanism in the car to dissipate the electrical power that regen would produce. Fortunately it doesn't take much driving before there's "room" in the battery for regen.

 

[GregH]

I had a 2013 rental for a few weeks and really enjoyed the B mode!! Not as aggressive as the AC Propulsion cars but much better than the 2011/12 'eco' regen. More regen at zero throttle and more regen at higher SOCs! I saw ALL regen bubbles just a few miles from a full charge.. 95% or so I think on the 2013 dashboard (maybe 92%-93% real SOC). Much better than the 2011/12 with almost zero regen in the first few miles and no full regen until about 80% SOC.

 

[CMYK4Life]

I'd say that use of B mode is situational based on what kind of driving you are doing. The following is my opinion, informed by way too much reading in this forum.

For high speed freeway cruising without much stop-and-go, you will do better in D, with or without ECO. This is because gliding and coasting will carry your momentum best, which is more economical than using regen because regen is inefficient.

For city driving with stop signs, traffic lights or freeway/highway with lots of stop and go, B mode will be helpful for the reason you stated, minimizing friction braking until it is needed in the last stage of stopping. The key is that you need to learn to modulate the throttle to avoid invoking regen when you just want to coast. The arc of power "bubbles" above the speedo is useful for easily telling when you are at zero power use but not into regen.

I've found that B mode is the most useful for aggressive "fun" driving, when it behaves likes engine braking as you let off the throttle, slowing you in preparation for a corner.

But I also use it in suburban driving depending on how much stop-and-go I'm doing. If the traffic is running freely, I might select D mode to enable better gliding, but then switch into B when a light turns red ahead and I know that I'll be stopping, in order to get as much regen as possible without invoking friction braking.

I use B mode exactly the same. Its great for driving fun and aggressive, turning corners, etc. I love to use it to coast to a few specific red lights on the way to work. I love to use it to 'time a light'.

I try not to use B mode around other drivers. When I let off the pedal I slow down a lot slower than other cars and this could cause a fender bender. I know I have irritated other drivers when I used it.

 

[TimLee]

I try not to use B mode around other drivers. When I let off the pedal I slow down a lot slower than other cars and this could cause a fender bender. I know I have irritated other drivers when I used it.

This is why NHTSA needs to get the rules changed and require the brake lights to go on at a certain level of deceleration. Whether it is an ICE decelerating from engine braking with just lifting off the throttle, or a hybrid /PHEV/EV decelerating due to regenerative braking; the brake light should come on. Would have been difficult / costly to do this 20+ years ago. It isn't that costly or difficult now. NHTSA and the regulators need to catch up with the technology and mandate safer activation of the brake light on ALL vehicles. :x :x