Best way to brake / decelerate?

I vote for option e: Stop as quickly as possible, and then hop out of the car and use the hand crank to manually increase the battery state of charge.



Wait, there isn't a hand crank...

Never mind...

 

:cheer2:

Ha ha, that makes a lot of sense.

I guess that what we all want to know is the level of regen efficiency vs magnitude of braking.

I'm pretty sure a Scangauge II device would help in that matter since I've heard that it's able to show the amount of Amps going out or IN the HV battery. But even there, during a test, one would need to record the amps AND the time that this current is supplied to the battery. Not an easy task at all.

 

remember that hint!!

owning both the gen 2 and 3, i am beginning to think the only reason the gen 3 is rated slightly higher for mileage is because of the screens it has that allows more info on what mode you are driving in. the HSI allows you to see how close you are to getting to battery power as you accelerate.

the objective is to accelerate as slow as you can without using any battery power. after i take off from a light, i accelerate to just past halfway which kicks on the engine, obtain my speed, then do what i can to keep the engine running ALL THE TIME which usually means keeping it just right of center if i have 6 or more battery bars.



eventually SOC gets high enough, that wont be possible at street speeds.

 

+1
Even for us unwashed non-hybrid drivers, it's always best to drive as if there's an egg on your brake pedal, and you don't want to get the inside of your car messy.

 

This is a very wrong advice. You might be getting decent MPG, but blocking the traffic and spreading Prius hatred. One is supposed to accelerate quickly (end of ECO, near Power) and then glide with no power when cruising speed achieved, especially when red light ahead. I'm getting 60+ MPG with this technique when city trip is at least 11 miles and it's not too cold. Max speeds are 55 MPH in my commute.

 

"Spreading the Prius hatred" hmm.. I think Prius drivers are just smarter and look ahead to anticipate stops. I've been driving this way with my late model Camry's pretty much right after I left my 16-17 yo range and started to appreciate gas savings. Its funny watching people swerve around me (because I am off the accelerator because I see a red light ahead) and they have to lock up their brakes.. If they would look ahead they can see all red lights and stopped cars.

 

yes either C or D. D would be:

D) perform initial hard breaking just enough to ensure that you can perform C all way to full stop then release brake and do C at 100% recharge rate.

 

D) As soon as you know you are going to need to stop, apply the brakes briskly (in the optimum regen range) until the car slows enough that you will glide to a stop (no regen), then glide. This reduces your average speed over the distance (lowest air and rolling resistance) while extracting the maximum energy you were going to need to throw away, as battery charging.

If you only suspect you will need to stop, this method should be tempered with a bit more momentum, to provide more options, in case you don't need to stop.

 

A comment made a while back, which I thought about and is of course true, is that if you are braking so late that you know you'll need friction brakes, you should try to use them early to "jolt" your speed down and then spend the rest of the braking under full recharge only. This opposed to doing full recharge only until you're forced to use friction brakes.

Two reasons this is better:

1) Safety (not braking late, trying to squeeze in charge)
2) Your average speed ends up being lower. This is good, since that means longer time spent recharging

 

I believe I read in another thread that the optimum regen rate (when you have to burn off speed) is half way into regen region in the HSI. While I will glide to the stop when no one is behind me and am in no hurry, more often when there is following traffic, I make it a hobby judging the optimum point to begin the slowing process such that I will come to a stop at just the right place, noting that slowing from 50 mph requires 4 times the stopping energy of slowing from 25 mph. This does not necessarily equate to 4 times the stopping distance (for a constant braking force) as air resistance comes into it. Also time to cover a given distance is much less at the beginning portion of the deceleration event due to the higher speed, and along with taking into account slope, etc., one's mind can have a lot of sub-conscience calculations going on. If one is in the middle of the regen region, one can slightly adjust left or right to correct for the early/late application of the brakes, as distance to stop decreases and distance judgement feedback improves. If I get it wrong sometimes bleeding off the last few mph from the teens down with friction braking is no big deal, noting that the fuel consumption penalty for using friction from 50 mph is 8 times worse that using friction from 12.5 mph if you ignore air and some rolling resistance. After all it's about optimizing mpg in real traffic and not in a secluded test track. BTW I usually accelerate in the mid PWR region when above 15 mph, because the low hanging fruit in optimizing city mpg is nearly all in the braking techniques, i.e. driving like you don't have any brakes, gliding not coasting, and yes staying out of the electric region (and not going beyond right side of PWR region) when motive force is required. One can read other threads for the other higher hanging fruit, for example, optimum HVAC use in winter/summer.