Automatic alternator cut out/regen braking
 

If the alternator produces parasitic drag when the field windings are powered up, but its not really needed to charge the battery, how about this for an idea?

A smart controller that cuts the power to the alternator's field windings in normal cruise or accel conditions, thus removing the electrical load on the engine caused by the alternator.
When decelerating (0% pedal and no fuel injected so 0% duty cycle) the alternator is switched back on and charges the battery at a high current, thus providing more braking effect.

If the battery voltage gets too low the controller can switch the alternator back in until its within a reasonable range again.

Any thoughts?

All new BMWs have this.
http://www.greencarcongress.com/2006...troduces_.html
Pair it with a deep cycle battery and you have yourself a winner.

This would be a real problem for us P&Gers haha.

Shouldn't be as the charging wouldn't occur without the engine turning :) :cool:

I'm sure even the most hardcore P&Ger has to brake sometime??? LOL

I read the whole thing now. It seems the system monitors battery charge, so if you get low enough it should just kick in no matter what. But, normally its not charging during acceleration. When your P&Ging, your engine is only on when your accelerating. :)

http://www.msdignition.com/2006/06-18.htm

http://www.msdignition.com/rpm_6.htm

http://www.msdignition.com/new_products/8940.html

These are links for switches that might work for you.

It would have to charge during accel if the battery got too low, well that's what I'd set my system to do :)

On board battery charger. Keeps the battery fully charged. Link>>> http://batterytender.com/default.php...855899dc011c2c

Use only one deep cycle "AMG" battery for everything including starting.

I used this set up in 2003 Suburban worked great.

Ok, I have it sorted. Two systems required. First is the duty cycle switch system which will switch an output if a duty cycle goes above a set value. This would be set to 1% and then the output reversed (so 1 is 0 and 0 is 1). Therefore when the duty cycle drops below 1% then the alternator is energised. The reversing of the output could be simply done with a small relay.

Secondly there would be a voltage controller switch that cuts the alternator back in at a set voltage (say 11.5v) and then switches it off again at another value (say 12.5v).

These circuits are available here http://www.autospeed.com/shop/category_579/browse.html

Item numbers KC5375 & KC5377

Nice link. Can't wait to hear how it works for you.

I still think you are better off just running a deep cycle battery charged at home every night and completely eliminate the alternator. 100 miles range is good enough for me 99% of the time.

I've posted this in another thread, but it's the same idea. If you MUST recharge the battery on the go instead of like tjts1 suggests doing, belt the alternator to a driveshaft and only energize the coils with the brake lights. That's REAL regen braking. You'd only be charging when you're trying to stop when you're trying to bleed off energy anyway and you could still put in a switch to kick it in full time if the battery got too low. The only problem I see is possiby the speed the driveshafts turning could be a lot different than the engine, but that just requires a different sized pulley on the alternator.

I'd love a write up if anyone has success.

I figure the easiest way would be to switch the alternator fuse on/off with a microswitch attached to the brake. Every time the brake is depressed, the fuse contact is closed and the alternator starts functioning again.

Low battery voltage can be solved by monitoring and using a switch to permanently engage the fuse.

- LostCause

Some good ideas, but I want a system that I DON'T have to plug into the domestic power supply after each journey. If I had that then I may as well have an EV ;) I don't think there would be enough braking time during a normal drive cycle to keep the battery fully charged..... unless each wheel had an alternator that was energised during the first stage of braking, and a second stage actuated the hydraulic brakes (two stage brake pedal)?

And why only regen when braking? I tend to use over-run deceleration more than braking. As the engine is already slowing the vehicle then why not regen during this phase? Of course this will also work when braking :D

My thinking too. I'd put the microswitch on the throttle. 0 throttle = charge. Besides charging while decelerating, that would also charge during my neutral coasts on the hills where the stupid a/t is pushing the rpm's up around 1100. I'd also add a parallel switch so you can energize at will (eg the battery is low, headlights or fan on, etc)

I've bought the parts for a manual version (wires, switch and ammeter). I'll have to remember to switch it on when I'm coasting. I've already tested to verify the engine runs ok on 12V (some ECU's prefer the 14.5V from the alternator). I intended to do a highway test to verify it also likes 12V when under load. But my daughter (she used to own the car) said she drove it 60 miles at night without the alternator, and she had no issues with the engine running poorly.

Sounds like a plan S2man :thumbup:

I've ordered the parts I need for my automatic system. I'm too lazy to flick switches :D

Let us know how it goes.

I love the idea of being able to "turn off" the alternator.

Simple question - how does one do that?

When I took the Metro engine out, it looks like it's just one big power cable that goes from the battery to the alternator.

Are we talking about disconnecting that cable, or something internal to the alternator?

If I just wanted to test the effect of the alternator on fuel economy, could I just disconnect that big alternator cable?

I really like this idea :thumbup: -- I'm looking forward to see if it yields some positive results (may try it myself). I have an ancient batt, though... It just may do it in (it's overdue, best I can tell is 6-years).

RH77

you're alternator should have some smaller wires plugged into it somewhere. Those wires comprise the field circuit. The field circuit is what "powers up" the alternator. If you break the field circuit, you turn the alternator off. When you complete the circuit, the alternator resumes its normal functioning.

Would simply interupting this field coil wire actually turn alt off and on. I think one of the small wires is for the dash light correct? How much juice goes through this field wire? My thought is to just interupt during acceleration like some do with a/c. I know it would only save a little, but would like to use this switch for both if current not too high.

sorry this is switch

http://www.cadentech.com/smartswitch.htm

Yes, interrupting the circuit could (and should) actually turn the alt "off." Supposedly there isn't much juice going through the field circuit, just a few amps.

Hmmm -- interesting: a Load-Based A/C auto-disconnect...

RH77

My problem is my a/c is on when my defroster is on, no manual overide other than to turn fan switch off. I remember to hit the a/c button during acceleration during the summer, but always forget during winter.
I figured if I am going to get this switch for my a/c clutch anyways why not have it interupt the field coil of the alternator during acceleration also. This is all dependent on:: Does interupting the field at one wire actually turn off alternator (and is this safe to do) and does the combined amperage of said field and a/c clutch current exceed 8 amp limit of switch. Has anyone safely used this method (for turning off alternator, manually or auto) and what is the avg current of said field. Link to switch again and THANKS!!

http://www.cadentech.com/smartswitch.htm

Why exactly would you want to disable a/c and/or alternator when accelerating vs cruising? What is the logic behind it, cause I can't really figure it. If I was trying to get the most hp to the wheels then it would make perfect sense, but since I'm shooting for FE I would be inclined to do exactly the opposite and disable them when cruising and enable them when accelerating.

Well maybe I'm wrong. I was taught in 7th grade physics that it takes alot more energy to move something from standstill to x speed than to maintain x speed once attained. Imagine two identical cars. Lets say 3000lbs, both with 2L 4cyl engines, auto trans. On an imaginary 300mi straightaway with stop signs every 2mi. It's a very hot muggy night and there are deer crossing signs everywhere, so both are running a/c and high beams. Both are identical except one has a little electric motor that gives it a 10hp boost from 0-55 and then cuts out everytime it accelerates, (kinda like a Honda Civic Hybrid)
Which car would have used the least gas at the end of the 300mi if they both travel side by side?
I do understand that your way would indeed achieve better overall economy at the end of the same aforementioned trip. But it would first require at least one deep cycle battery and a driver who is not only much more tolerant of heat than I, but also with better night vision. I guess I would rather have the brighter high beam lights and a cooler car interior. That would indeed be a tradeoff on my part.
The little 10hp motor on the imaginary car above can be had (more/less) by cutting off the a/c and alternator during acceleration.
Then again, maybe I'm wrong. If so please point out my flaw before I spend 80 bucks on this switchy thingy. THANKS

The way I was thinking about it is that due the the ICE nature to be more efficient at high loads, the fuel cost of an hp at high loads (acceleration) is less than an hp at low loads (cruising).

You're statement about an ICE is indeed true to the best of my knowledge. Ideally I would use you're method and just go WOT between stop signs until I reached a velocity that allowed me to shut engine off and coast to the next stop sign, with a/c and alternator only during that time, it just isn't practical in the real world. I admit that my way is just a workaround to save a little with the way cars are designed today.
I figure coasting as far as I can to a stop sign once doesn't really save me alot of fuel, but do it everytime the oportunity presents itself and it can really add up. Same on the other end, if I relieve my engine of 10hp of work while it is trying to get me up to speed everytime it will also add up.
Honda does it with the aforementioned Civic Hybrid, I believe they call IMA and now even GM has there own little starter/alternator/motor that accomplishes the same principle. The one thing those and even the Prius have in common is they all work to remove work from the ICE during acceleration. For the most part this greatly boost their city numbers. Most of their highway numbers can be beaten with a VW 1.9L turbodiesel.
I don't have the 1000's it would take to re-engineer my little Mazda Protege to work the way these vehicles do, but I figure if I can do at least some of what they do for 80 bucks and some wire that I may actually see my ROI before the car rusts out.
The Mazda is EPA rated for 22 city 28 highway with a 2L auto trans. Mostly through driving technique and a few little mods so far I avg between 29.5 (lowest in winter with winter gas (CNY winters that is) and 34.8mpg my best tank avg I considered accurate. I would just love to break that illusive 35mpg I can't seem to get (w/o royally pissing off other drivers that is)
I did just build one of those PCV condensators. No not the simple air compressor water seperator ones. Pretty neat little device. First day of driving
(40mi or so) collected 4-6 drops of oil. Not bad considering my engine is still pretty tight and only 55k on the odo. I don't believe the MPG claims at all, but if it keeps my engine cleaner and would just give me that 0.3 mpg I need to break 35MPG then it was well worth the 2hrs and $30 for materials.
Sorry so wordy today, but my original question and reason for post was,,,
Has anyone actually used the field coil wire to effectively turn their alternator on/off safely and any idea of the juice involved. THANKS

A PCV catchcan is on my todo list. I was going to go with the compressor water separator, but I would like to see how you did yours. Could you please post it in a new diy thread?

My plan was to disable the alt. except when NC or decelerating (the automatic trans keeps the rpm @1100 during NC on hills). I hadn't thought about the higher engine efficiency during acceleration. Hmmm. I'll keep that in mind if the "free" energy isn't enough to keep the battery charged.

some alternators are one wire everything is inside

but most energize through the light or resistor if the light burns out or by the computer, on the first alternators if the light burned out they quit charging.

"Has anyone safely used this method (for turning off alternator, manually or auto) and what is the avg current of said field. Link to switch again and THANKS!!"

it wouldn't hurt the alternator, what about all the electronic else where?



if i put a 140 amp alternator on the drive shaft, that's over 2 HP, i will feel that baby when i hit the regen button.

I like your idea best of most posted. That is to charge whenever accelerator is off. You stated you have the parts in an earlier post. Can I ask how you plan to cut of alternator with your microswitch.
Also don't quote me on efficiency of engine while accelerating. I believe that is probably it's most innefficient time. I only meant that an ICE is most efficient at WOT and fully loaded. Such as a generator charging a large bank of batteries. Not a car engine while attaining RPM.
I think your idea is a great one if well thought out. I'm just curious how you plan to implement it.

As far as the PCV catch can design I used it can be found here::

http://www.himacresearch.com/books/hydro8.html

Use a wide mouth Ball canning jar and lid. Instead of little V8 can use an empty small tomato paste can. It is actually kind of a cheap knock off of one I seen selling for $150

I just suggested someone else put *their* microswitch on the throttle - I don't have one. :) I bought a toggle switch, which I intend to mount on the shifter so it will be handy when I go in and out of neutral. I've just got to find time to install it. (Where do I get more time?)

I don't need to take your word for engine efficiency at higher throttle positions. The BSFC maps bear that out. Sure, that's a bad mileage time, but the engine is running efficiently. I definitely won't be charging while at idle.

All the parts have arrived for the automatic electronic alternator/regen conversion.

Time to build it :)

Has anyone considered which deep cycle battery they are going to use because I don't think a regular starting battery will last very long??

I'll be letting the alternator cut back in at 12.2 volts, which equates to 50% charge.
That's if the regen charging isn't sufficient to keep the battery topped up.
So the battery will never discharge less than 50%, hopefully allowing the battery to live a bit longer than if it was fully discharged then recharged.

Ax, it would be extremely nice of you if you could document the process. I'm sure it would benefit a lot of people.

I'm running an AGM battery.

Even deep-cycle wet batteries shouldn't be discharged past 50%.

Circuits are built & ready to fit.
Both are supplied with relays fitted to the PCBs. Either can switch the alternator back in.

The system requires 6 wires:

Ignition switched positive
Earth (negative)
Positive voltage sensing wire to battery
Injector supply sensing wire (back probed from ECU output)
2 Field supply wires from & to alternator.

The field supply to the alternator needs to be cut and diverted to the control circuit, otherwise its easily removed.

The point at which the duty cycle is set to switch the alternator back on is programmable by push buttons on the circuit, as is the hysteresis. The duty cycle is displayed on a pair of 8 segment LED displays, which is on a long ribbon cable for easy dash mounting. The display also functions as the programming interface.

The voltage switch point & hysteresis is adjustable by 2 potentiometers on the voltage switching circuit board, and can be set to any voltage easily with a multimeter. An LED indicates when the voltage based switching circuit is operating.

Oh, and the LED duty cycle display is self dimming at night with a variable brightness control!

http://ecomodder.com/forum/attachmen...3&d=1206565721

Awesome job, AX.