Regenerative braking?
 

I was thinking... In order to lessen the load on the alternator, or even make it easier to eliminate the alternator altogether...

Could you retrofit a regenerative braking system onto a non-hybrid car? Like find a junked insight or prius and pull the brake systems off them.

If you could, then braking would be far less of a worry for the hypermiler, and the alternator wouldn't have to work nearly as hard to keep the battery charged.

Or is it something far too complicated to fuss with?

I would be interested in this as well, but I'm uncertain of the viability of doing it.

Then again, I can't weld. I'm sure if I could it would bea much easier project.

The regen braking in the Prius is in the electric motor that moves the car not the wheels. It really is regen engine braking regulated by the gas pedal and brake pedal. There is no easy way to do it without some sort of transmission connection and maybe a clutch so you don't keep spinning the rotor of the alternator all the time.

I've toyed with the idea of an AC clutch on an alternator that is coupled to a driveshaft.

Problem is that regen is only like 18% efficient when reused for traction, but it would be more efficient than having the alternator spinning with the engine as you could reclaim SOME energy lost in braking. There can be good mpg gains in no alternator (like up to ~%10), and if it is only used in braking then even better. But you would want to gear it such that it actually recharges when you brake, and would have to cycle it on hiway trips.

How about some clutch activated device that winds up a spring or some elastic stuff. This would only be good for about one stop and one go but that should be enough. (A stop is always followed by acceleration.). The conversion efficiency should be pretty good.

Another idea would be to use some analogy to the "bottle rocket" with water and compressed gas to store and release a powerful burst of impulse. Air tools are very simple, robust and compact and have a high power to weight ratio. Efficiency is bad but maybe it could be improved a lot by using a fluid in the system. I wonder if the compressed gas can be taken directly from the exhaust system?

Other projects (including getting my solar panel wired into my car's battery) are still a higher priority. However, considering my successes with lowering electrical usage (but keeping the alternator hooked up), and the reported successes of others disconnecting their alternator, I have toyed with the idea of having a three position switch put on the dash:

Position 1) Normal alternator, just as I have now.

Position 2) Alternator is electrically (although probably not mechanically) turned OFF. By simply turning off the alternator electrically, I'll still suffer the "static losses" for spinning the belts/etc. But by electrically disconnecting the alternator, all actual "electrical drag" would be eliminated. And if the alternator is one of the many on the market that has an on/off "control wire/signal" with it, I could probably get away without even needing to use a relay to disconnect the alternator (and instead just play with the wiring to the alternator control signal on the alternator itself).

Position 3) This is the key "pseudo-regen" position. In this switch position, the actual alternator control signal comes from the same car circuit that the brake lights are wired up to! By doing it this way, the alternator is off normally, but turns on the instant your brake lights come on. While the brake lights might not be the best "regen braking" control out there, they are easy to wire up to, and they do at least signify that you intended to slow down (so they aren't a totally unreasonable control either)!

NOTE: I would suspect that such an arrangement would give you more "regen braking" than you get normally with the alternator connected all the time. The reason I suspect this, is that alternators do put more drag on the engine when more electrical power is needed. And more electrical power is clearly needed (to charge the battery, if nothing else) if your battery is running a bit low (as it likely would be if/when you have otherwise been running with the alternator turned off). So such a wire setup may actually save wear on the brakes (by giving you more regen braking than normal), even more than it might help you go with "alternator off" for extended periods of time.

Again, this isn't a complete solution. It's just a thought for one cute way to retrofit a limited "regen braking" mode into an (optional) "alternator off" switch. And since I've not actually tried this myself, YMMV. But unless I'm missing something in my tentative design, this should be reasonably easy to wire up, as well as at least moderately effective. But I guess we will have to wait until someone tries it, to know for sure...

Maybe a good idea to get into the alternator and drop the output voltage a bit normally then bump it up to full voltage when braking or down hill with your foot off the gas. Next step would be a bigger more efficient alternator that can put a bigger load on the engine when you need it to charge. Only problem is the battery takes a beating.

I think BMW has some alternator smarts so that it works more for some regen. There's many little things they auto manufacturers could do if it got into a features war on less expensive cars: autostarts, electric water pumps, steering, AC etc...

I'd love for vehicles to come with a 110 volt plug and the option to set a timer for warming up the interior and a warmer engine. it could monitor when to start the block heater and then the interior preheat based on outdoor temperature. Smart outlets in malls would help.

Heck if you had those pay plugs in parking lots and had a fast charge short range EV or vehicle that can go EV for short trips it would be ideal if there is greener electric capacity. If uou could get the loads and distances low enough then the they could do another short hop 10 miles maybe, after maybe 45 minutes... dunno, but it would be interesting.

Mechanically it may be feasible, but not as a practical application on a non-hybrid because there simply isn't enough of a voltage requirement in the first place.

I got to a point it's not so much about the mpg anymore, it's about how long a tank of fuel lasts. I can drive slightly more aggressive and don't have to hold up ten miles of traffic so long I leave the car home most of the time, so to me the biggest booster is not driving.

I was amazed, it consumes NO gas when the engine isn't running :p

I'll contribute a few ideas:

- A turbo driven alternator
- Having an alternator being driven by fluid in an automatic transmission. Then you can charge a battery more and brake at the same time by downshifting.

I would think a different size pulley for the alternator could reduce alt. rpm's and thus load, thou it would also reduce battery recharge and for this matter just getting a lesser-amp alternator would have a similar effect and the last thing I'm doing is messing with that!

Yes I think a solar panel that can recharge the battery when the car sits might help, if nothing else it's free energy, but whether it will help mpg on a non-hybrid is still doubtful.

A 30amp alternator simply doesn't put much strain on an engine, maybe with ALL accessories running (wipers+fan4+lights) but that's somewhat unusual.
The a/c is far worse, that's where to start with economy, so long the a/c is running there's no need to think along the lines of alternator improvements.

There might be something to it at this angle.

This all leads back to what I and Dan at eCycle thought up and that is to add one of their ISA motors (Integrated Starter Alternator) to your car and use it to start charge and drive your motor thus making it a parallel hybrid and all you need to do is add a higher voltage battery and their motor and controller and some sort of control system to make it all work. Basically you operate your gas motor like usual and add power to it from the electric motor which also recharges the battery very efficiently - more efficiently and quickly than the convential alternator. Plus by operating at a higher voltage and up to 450 amps you charge and regen brake with more energy that an alternator. Now if there was only a way to get the engine to freewheel by holding valves open or maybe closed you could run on pure electric right though the conventional drive train. All you have to do is connect the motor with the right size syncronous pulleys and a belt off the crank pulley.

I keep thinking about harnessing the thermal energy by running water through tubes against the brake pads. The intense heat would create steam. There has to be a good way to capture this energy such as a steam turbine alternator.

Well now that's an interesting angle, to have regen braking do 99% of the battery re-charge, the alternator itself does almost nothing while driving. DO keep in mind the spark plugs need a lot of power, specifically the coil, reduce this and you reduce engine efficiency. And yes, if you reduce the spark's power too much your mpg will suffer, I am 100% sure of this :p

But you know, you're as well off if you have a clutch-driven fan to replace that with an electrical thermostat-controlled one, they're like 80 bucks each and a short afternoon... Supposedly this shaves 4-5 hp off the engine load, but I will also say that doing this to a 1988 T-bird didn't do anything I could feel or notice, neither in performance nor mpg, mostly a waste of time it was.

Another idea is high performance alloy pulleys (like for racing), they're made of a light weight aluminum and might be slightly larger in diameter to allow rpm reduction. Still, I checked into this and most are for racing only, they're just not practical in road applications because it will over time do more harm than good.

I think he means an under drive pulley. A lot of race enthusiasts use them to free up some power by reducing the diameter of the crank pulley so all the accessories run slower and hence take less power from the engine. I personally have never recommended this because of the fact that it does turn everything slower.

As for the alternator being switched. Wouldn't it be better to connect it to run as long as the throttle body is fully closed? Especially for the people here that rarely need to use their brakes. At lights when I drive a manual, I don't hold the brakes if it's flat.

As for harnessing thermal energy. What about getting it from the exhaust? that gets more than hot enough. Especially at the catalytic converter.

Here is a good overview of different methods of using waste heat to regain power: https://www.heat2power.net/en_benchmark.htm

What about replacing the rear brakes with motor/generators? If they were both 5 HP you would only really need to store 30 seconds of charge or so. 600 amps is about 10HP do you would need to store about 600/120 5 amp hours. Put a switch when you barely press on the brake pedal it goes to full charging. Put a button on the top of the stick that goes to full power forward. Push the button for a little while on start and then drop it in second. Save a lot on the clutch wear and gas

two motors of that size should be able to lock up your wheels at nearly any speed.
For what you could spend on designing your own system, there at least used to be a system that was avalible that would replace your alternator with a motor/generator, giving you both more power, and regen braking, and it was suposed to be rather simple to install.

I've been thinking along DracoFelis' lines; disabling the alternator during cruising and enabling it during braking. Except instead of just turning the alternator on when braking, I would enable it any time TPS is at 0. This cover the braking situations, and generate some juice while downhill coasting. When I neutral-coast with my automatic, the engine continues to spin at around 1100 rpm. Turning the headlights or heater fan on reduces the rpm by about 30 for each. So I know the alternator is working at those rpms, and I figure I could use some of those 'free' rpm's to run the alt. (I know, they are not free. The energy is coming from my momentum or from gravity at 0 TPS) I would also enable the alternator anytime I was using high-load accessories, such as the headlights or heater, to prevent excessive discharging.

I've got a 100 amp alternator for decent charge rates. And an AGM battery, which should handle the discharging and rapid recharging just fine. I ordered an ammeter and pillar mount this week, so I can monitor the charging system better than with just a volt meter.

Now the question. I see Metro removing his belt, and Brock pulling the fuse, to disable the alternator. Has anyone cut the field wire to their alternator to disable it yet? I may be the guinea pig. :)

As mentioned, BMW has experimented with the idea of using regen braking in place of the alternator. If the charge gets too low, the alternator is then engaged to produce the needed power. ( https://www.autobloggreen.com/2007/03...raking-system/ )

I hate braking. If there's any single enemy of the hypermiler, it is braking. Brakes are designed to remove energy from the system. Now, there are methods you can use to limit how much braking you do, but you can't eliminate all of it.

There are many, many ways to do regen braking and probably even more uses for it. Personally, I want a system that will power my car at about 5mph for intermittently for maybe a total time of 2 minutes (that's 2 minutes of rolling at 5mph). PWM would do wonders for it once it got rolling. Here's why I want this. Whenever I'm in traffic at rush hour, I'm constantly moving a little forward and then coming to a stop for about 30sec. It puts quite a strain on the battery and starter to keep shutting the car off and turning it back on. It's also a pain in the *** and the angry souls behind me probably get all pissy if I'm my front bumper isn't almost touching the rear bumper of the car in front of me.

It seems as though the most efficient regen braking is electrical in form. My car is front wheel drive, so I'm thinking one of the rear wheels would be a prime candidate since there's a limited number of stuff in the way back there. Any thoughts on how to accomplish this or what sized motor would be needed? It'd be great to just engage a big 'ol spring between the rear wheels when slowing down and then releasing its energy as needed, but I don't think that'd work all that well.

Matt

I think that you'd just make a three position switch normal, off, regen. Where normal: the voltage from the ingnition switch goes to field like normal, off: the voltage does not go to the field, regen: the brake light relay goes to the field.

I think the field is there so: the engine turns off when the ignition turns off and so the field voltage does not drain the battery when parked. Otherwise it would just be hooked to the battery full time.

I don't think you would get much stopping power as a 60 amp alternator is only a little over 1 horsepower

"Any thoughts on how to accomplish this or what sized motor would be needed? It'd be great to just engage a big 'ol spring between the rear wheels when slowing down and then releasing its energy as needed, but I don't think that'd work all that well."

I think an air compressor and tank would be lighter than electric motor and battery

You know, the air compressor idea was one of the other options I was thinking about. I could also possibly weld one of the frame rails closed to use as a tank.

An air pump may also do a better job of braking.

Good thinking.

I just DWB, problem solved.