Regenerative braking?

[8307c4]

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.

Originally Posted by mjo

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.

There might be something to it at this angle.

[JanGeo]

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.

[Jim Dunlop]

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.

[8307c4]

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

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.

[dkjones96]

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.

[GasSavers_HAHA]

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

[FritzR]

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

[GasSavers_Ryland]

Originally Posted by FritzR

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.

[s2man]

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.

[DrivenByNothing]

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. ( http://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