Best way to brake / decelerate?

I think C would answer your question.

So you just want to try to charge the battery or are you trying to get the best mpg?

 

Good question!

I normally just coast to bleed off speed, and then do final braking as I approach the final stopping point. It may not be optimal, but it's most convenient with a lot of stop and go traffic.

To maximize regenerative braking, I think the goal would be to maximize the time where the CHG bar is over half full (but not maxed out). At low charge rates I haven't seen the battery charge increase much at all, presumably because losses in the system for voltage conversion result in little real charge returned to the batteries.

This, of course, assumes that you KNOW you will need to stop. If you're able to decrease speed until the light turns green or until traffic clears, then so much the better since you can avoid the need to accelerate from a standstill.

 

Someone else mention to drive like you don't have brakes. Of course traffic these days doesn't always allow for this but it does work good when you can glide.

 

I have always wondered at what point on the charge bar or at what speed does the friction brake kick in? This way I can keep it in regen when possible.

 

The switch over is around 7 mph. Oh course you slam on the brakes and the switch over is instantaneous.

 

Adamace1 asks a relevant question that you should hear again:

Do you want to charge the battery as much as you can, or do you want to maximize fuel savings? They are NOT the same. Recall that hypermilers take the battery out of the equation as much as they possibly can. There are inefficiencies in charging and discharging the battery. The momentum of the car is totally wasted with the friction brakes, of course. But understand that you still loose MOST of that momentum even with regen. You get just a fraction of your energy back out of the battery as motive force. So the bottom line - use your brakes (including regen) like they don't exist.

 

If there is a stop sign and you must stop I use c as you get more regen with that system of braking.I keep the braking as light as possible. H

 

As others have posted, try to coast and avoid the stop. That is your best bet. If you can't do that and must use the brakes to slow down, try to use moderate braking. Heavy braking may exceed the capacity of the regenerative system, forcing friction brakes to come on line. Very light braking, at least with the Gen IIs, is less efficient since there appears to be some fixed overhead in the inverter system. In very light braking a significant portion of the regenerated power is consumed by this fixed overhead. Braking a bit harder puts more into the battery. Of course it's possible that this has changed for the Gen IIIs.

Tom

 

Assuming we have to come to a full stop...
d) Perform continuous breaking with constant deceleration until 25 mph, shift to B for max regeneration, then shift to N at 7 mph to eliminate the power consumption of creeping.

Ken@Japan

 

charging or mpg's? must be lost in translation.

 

I always brake using the C method. I never brake with HSI maxed at regen if I can help it. Of course if someone cut in front of me or if light turns yellow, I brake hard if I have to. Using the C method, I constantly have 7 bars on the battery charge.

 

A constant 7 bars is not a good sign. Did this start happening recently?

Tom

 

It's a great sign. my mileage is higher with 7 bars than with 6 bars. I accelerate into the pwr bar on HSI and use only regen for braking. I avoid friction braking if I can. I can easily go 2 miles on EV and still have 3 to 4 bars. Ok it's not a constant 7 bars but I get 7 bars half of the time in city but never 7 bars at highway speed. I'm only getting 7 bars now that I'm not using AC so yeah it happened recently.

 

For those who say you should not maximize charging when stopping--I think that's not quite so. As I understand it, when you slow, you usually do not burn gas--so the real question is how do you use the energy from the gas you have already burned--and saving as much as you can in the battery is a good idea.
I suspect that your choice C is the best shot there, as it maximizes regeneration.
I would also say that dcscm's point that strategizing to keep your minimum speed as high as safely possible is a good one--even though your hypothetical is the case where this is difficult or impossible.

 

if you must you must. what others are implying is that if you must stop, that usually means you are driving too fast. there is no reason to drive normally up to a few hundred feet of a light you know will be red.

that is not a great sign. 7 bars usually means your battery capacity is failing. in city driving for me, i try to stay at 6 + bars, but that is hard to do and drive efficiently. i am frequently in the 4-5 bar range.

 

Who would they be?

I see more of a message to think back to the last fuel burned before needing to stop -- could some of the burn been avoided by some better planning? For typical driving styles, the answer is very frequently 'yes'.