Electric Assist Project: E-charger (2000 Subaru Outback)
 

The What: An electric motor assist with PHEV capabilities.

The When: Should start work in the next month. I plan to get the batteries with the next paycheck and the motor with the one after that.

The Why: Partly for fun, partly for fuel saving, partly for just outright doing something that hasn't been done before.

The How: Less than 5000$

And begin..

OK, after some research, I've started saving up my pennies (and nickles, and dimes, and quarters, and dollars..) to buy the necessary parts. Here is the current plan:

Start off with 8, 6Volt Trojan T105's that I can get locally for a good price, giving me a 48V 225AH pack. These will fit in my trunk area without limiting too much space, and I would still be able to access the spare tire well. I plan to keep the car as functionally stock as possible with this project. And Subaru's are very annoying if you don't have a full sized spare with you. (Ask me how I know that.) Ideally, I'd like to cover up the batteries with something like a fake sub-woofer box to hide them, but that's way down the line.

With the batteries in the back, an independent throttle somewhere in the cabin (Thinking the gear shifter right now, but nothing certain) I plan to get an electric motor from Thunderstruck EV, and am considering to attach it to one of 3 points:

1) Chaining it into a half-shaft and powering one wheel with the motor. This is what Coyote X has done with his Metro, and it was shown to work.

2) Bolting it between the drive-shaft and the rear differential. This is what the Eco+Muscle project did on there similar project, and it was also shown to work. The only plus side I see here is power would go to both rear wheels versus 1 wheel using method 1. Both of these methods have a problem with proper gearing (An important aspect in WV, both of these methods would essentially have a 1 speed transmission, I either wouldn't have enough power for hills or I would run out mph on the highway and over rev the motor) which leads me to option 3..

3) Attaching it directly to the engine via a drive belt. A sort of "Electric Supercharger" This would be the most practical, but probably least efficient method. (Since the stock engine would still have to spin up to RPM X to get me moving, according to scangauge this max's out around 100 mpg, but in neutral I've seen as high as 400 mpg). Essentially, the car will be driven normally, but with the assist it will drive as if it's always going downhill. This method is probably what I will be going for. I was worried that the belt might not be able to handle the power at first, but I realized that a parasitic drag of a supercharger is anywhere from 25 to 100 HP, and that power is transmitted via a serpentine belt. If that much power can be transmitted via a belt, why couldn't it work in reverse?

Using either of the first 2 methods, I was worried that gearing would be a major problem. I would either not have enough gearing to go up hill, or I'd have to find a way to disable the motor after XX mph. Using method 3 I still get to keep full use of the stock transmission, giving me proper gearing at all times.

Here is a picture of a similar engine bay to mine, that someone added a supercharger too:

http://i131.photobucket.com/albums/p...d/IMG_3467.jpg

http://i131.photobucket.com/albums/p...d/IMG_3466.jpg

The e motor would be roughly the same size, so assuming I can get a proper sized pulley on the motor, it should be good. I'd also plan to power the crank directly with a 3rd belt instead of powering it off of the P/S pump as shown in the picture. In fact, the person who did the above later used the same method!

http://i131.photobucket.com/albums/p...d/IMG_0259.jpg

Lots more piping and things in this picture though. But you can see what he's done still. He says it works well and he's completely satisfied with it after many miles. :thumbup:

One last thing: I can't simply put the car in neutral and go around with the engine off, the transmission's clutch pack will not accept it and will burn up in just a few miles.

Any questions or comments from you guys? I'd like to have at least someone tell me this idea could work. :eek:

It could work - BUT, 500+ pounds is a lot of extra weight to be carrying around all the time. And if you put all the batteries in the back, your vehicle might be a little tail-heavy. You might need helper springs or higher-rate springs in the back. And watch it on the curves!

I highly recommend Mike Brown's book Convert It! as a great guide. He shows how to build an EV safely, and what he says should apply to what you're trying to do also.

It will work, and it will be a lot of work. :)

I don't like option #1. Too much problem with suspension and the drive axle moving around on you.

What motor were you thinking of using?

Option 3 is the better, and I can explain why.

Less fabrication, and almost no modification of the vehicle. Simple is sometimes much better, and generally more user friendly.

You have to use the transmission anyway; as you said you can't go around in neutral, BUT you could get most of the benefit of coasting with the engine off with the electric motor in place of a supercharger.

As you likely know, when the vehicle is coasting in gear, the fuel turns off. Breaking that down, your throttle position sensor reads 0, your vehicle is in gear which keeps the crank turning, so the computer turns off the fuel. If you had an electric motor helping to keep the crank turning for longer you would be able to have extended coasts with no fuel being burned, which is equivalent to coating with the engine off.

Since the only scenario where the fuel would go off would be during 0 throttle, a switch could be wired to activate the motor when the throttle is at 0.

Option 3 also means you'll only need a limited rev range for the electric motor, which is right in its ballpark.

And with the correct sized belt, they are capable of handling extreme torque and power. Many industrial motor applications use belts to transmit power, and generally do a great job of it. Somehow I doubt you'll be needing all the power a good belt can transmit.

Obviously there are huge gaping holes in how to do it, but with the EV community alive and well here, I doubt it'll take long to learn what is needed.

Good Luck. I've been thinking about doing the same exact thing myself.

some cars, like an alpha romeo I recall, have the transmission in the rear. So that adding an electric motor between the clutch and transmission is relatively easy (sprocket).

Patrick: I regularly carry upwards of 1000 lbs inside the car, and in highway driving it seems to cancel itself out with pulse and glides. I know in the city my mileage will be worse, but the battery pack should pay for itself then. (: The car already has heavy duty overload coils in the rear, stiffer struts all around, and upgraded swaybars front and rear, so I know it can handle the weight.

Daox: Yes I know it will be but a lot of work sounds fun to me. (: I plan on going with the AC12 from Thunderstruck. They recommended I go with 72V with the motor, but I'm going to try 48V first to see how it goes. 72V would be a problem with my goal of keeping the car functionally stock (Don't know where I'd set the 4 extra batteries) I also know I could probably get by with a smaller motor this way, but I really wanted regenerative braking and for the system to be able to pull it's own weight. Looking around, it looks like the only thing I'll have trouble making myself will be the pulley on the motor. I might have to find a machine shop to match the splines to a pulley to connect to the crank. The motor is good for 7000 RPM and my stock engine maxes out at 6000 RPM, so to match them up I'm going to go for close to a 1:1 drive.

Shadetree: Watching the scangauge, at low speeds (<40 mph) it is very hard to get my automatic to go into fuel cut. It's also downright impossible to get it to fuel cut with the A/C on, but that's rare that I use it anyway. But when the engine does go into fuel cut, the electric motor is going to have to move the weight of the car AND turn over the (not running) engine it might be a bit much power to ask of it, which is why guessing from the scangauge, the motor will still spin up to accelerate but be using very little fuel. Even with the the throttle closed I still don't always see fuel cut unless I'm decelerating. I can go down a mountain and will gain speed and hover around 100 mpg. This is true from about 35 mph all the way up to 75 mph. Even though I'm gaining speed, the motor has to use more fuel to spin the motor up to X RPM. It might take some getting used to, but I do plan to have 2 independent throttles. This also has the nice ability that anyone can drive the car, I'll just have a switch that I can turn the E-drive off.

Just a thought. If you do somehow wire it so that when the engine cuts fuel the electric motor takes over, be sure to turn the electric motor off when braking.

Also, not sure how you are going to get regen braking in this scenario.

Good Luck!

LDJ

Why? Is this a regular clutch or part of the 4WD system?

If you really want regen, you should have it so it can capture the max amount of energy. I'd avoid the engine accessory belt setup.

Also, why not go with 6 - 12V batteries?

I've thought about this (but haven't done anything) and came up with a few possibility:
1- mount it where the AC compressor used to be, easier for me than you, as my compressor is in a box in the spare bedroom. There are a lot of complications with this, and you seem to have spotted most of them. And I don't really know if that little belt is idea for transferring more than 5hp

2- mill gear teeth into your brake disks (2 or 4 of them) and mount a little brushless motor to you strut mount. This would require a lot of machining and you would only be able to gear it for the highway, but that might be okay...

3- (the one I'm considering at the moment, if only I had the $$) A electric assist boat tail trailer. Two birds with one stone. It would be a little hairy having a trailer pushing your car, but with the right linkage it could work out. This idea needs much more planning.

Edit: Speaking of boat-tails, can you hit me up with a link to your boat tail thread? I found it via google some time back, but I just skimmed it then. never mind, found it.

For manual controlling of the motor; I was thinking a T-handle throttle from a boat would do the trick (and with style), with a switch to put it into a charging circuit for slowing.

I really like this concept and would love to try it myself. When I first read your post I thought "yeah, why the heck do you have to buy a new vehicle to have a PHEV?" I think it would be great if you could just bolt on a kit that would swap out the A/C compressor with 5-10hp electric motor. I envision something with a similar clutch as an A/C compressor that would allow you to turn the system on and off as you wish. Any idea of what kind of range extension or mpg increase you might get with an extra 225ah?

Well lets say we have a 25% mechanical loss (low end guess), so that brings us down to about 170ah, at 45V that's ~7.6kw hours, or about 10hp hours.
That's roughly the energy you get out of 1.5 gallons of gas per charge.

Patrick: Yup. The AWD clutch pack (center differential) requires the engine to be running while moving. A big disadvantage when you want to hypermile.

Daox: I'm not attached to regen really, but I was thinking simply slowing down without brakes (gearing down) it should still regen? I also don't know how much regen amps my batteries can take. As far as why them, I know they're proven and they're cheap is why I'm going for them. Plus, I can fit all 8 without losing any real trunk space:

http://ecomodder.com/forum/attachmen...5&d=1279698729

I do think higher voltage would be a good idea. Ask any EV owner, the higher the voltage the better.

This may be a stupid question. Would the electric motor have to overcome compression in the ICE engine or would it only operate as an assist option ?

I like the 'electric supercharger' idea. I was considering the Mars or eTek motors, but the AC12 looks good too.

If you want to go direct-drive, you could always toss out the RWD portion of your AWD and directly drive it with the electric motor. As a side effect, if your batteries were getting low, you could recharge them by regenning slightly while having the ICE power the car.

Remember that in either case, you'll have some heavier batteries on board. That means you could power the PS pump and A/C compressor with a small electric motor (90VDC treadmill motor, perhaps?) and toss the alternator for a DC/DC converter, reducing parasitic drag on the engine.

A battery pack with that many KWh would let me do most of my trips without firing up the ICE, assuming it can provide enough amps.

As the owner of a plug-in mild hybrid, I can tell you setup #3 will prove inefficient on short trips. The ICE ought to be moderately loaded or off for best efficiency, but with heavy assist, it's just going to be lightly loaded all the time.

I like the option of driving the rear diff with your electric motor. Alternately, delete the rear diff and drive one rear CV axle with your motor if that would get you a more appropriate motor speed.

I'm liking the rear wheel drive idea, you could just re-angle the diff so that the electric motor was where your spare tire would be (the back seat seem like a fine place for a spare anyway). I guess that would make it difficult to change the diff oil... well not to drain it at lest...
then there is the problem of the wheels connected to the ICE. It would be really nice to have locking hubs like on old 4WD trucks.

Well I should be ordering the motor/controller today or tomorrow! Here is hoping. The teardrop trailer needs to get finished (doors and trim still needed) before I can start on this project, so it still might be a week before I can start making any progress.

Robert: Yup, I know that it is an inefficient method, but it's also the most practical and should be the easiest to fabricate. I'll probably get a block heater at some point since the engine will never warm up under heavy electric assistance.

Jerry: Ayup, that's my back up plan if the belt method ain't work. Every thing seems to have advantages/disadvantages at this point. I'd worry about gearing with the single gear ratio though. I've also considered a pusher trailer, mainly so I can switch it easily from car to car, but don't know how that would drive either. It's worth looking into though.

Obviously mine was a stupid question. :D

Arragonis,
I think the plan would be for it to just assist, so the engine would still be turning with out this, it would just be putting out less toque than with the whole system.

Brucey,
Which motor & controller are you getting?

On the engine not going into fuel cut, it could simply be a matter of adjusting your throttle position sensor so it reads 0 when the throttle is closed.

I realize it'd have to move the vehicle + turn the engine, but even with just extending your coasts, it may be worth it.

Assuming your Subie wouldn't get too pissed about being turned into a 2wd, I like the idea mentioned of using your rear (or front, depending on ease of application) as the drive axle for just the electric motor. But your AWD transfer case would likely get pissed off about it. Where is your tranny located, under the hood, or under the floor? Ie, is it a front wheel drive car with auxillary prop shaft to the rear, or is it a rear wheel drive with transfer case sending power to the front? Only Subie I ever saw was an older Legacy, and it had a transverse mounted engine like a front wheel drive.

regarding option 3 (turn the engine over with an electric motor and drive the car that way). Most cars already have a motor that turns the engine over, the starter, so it is easy to get an approximate idea how much power/efficiency that will cost.

If your starter takes 200 amps, at 12ish volts, thats a 3.2 hp penalty for turning over the engine at sub-idle speeds, say 500 rpm. If you need 3000 rpm then you need at least 6 times 3.2hp to keep it running, or 20 hp, probably a lot more.

This is totally wasted power from the battery to wheels perspective for option 3.

Compound with extra weight/cost of the electrical setup.

The other aspect is if you "boost" the stock engine during cruise you will move the engine farther from bsfc and reduce its efficiency.

Just my $0.02, maybe I'm wrong.

Arragonis: Oops. Didn't see your question. Yeah, it would have to force the motor to turn over too. I think anyway. I'm yet to see anyone actually do it this way so it's all pretty much theories right now.

Jerry: AC-12/ whatever controller comes with it.

Shadetree: Yup! It's possible, although I don't know how much my trans would like it. They're notoriously picky. I guess I could swap with a FWD trans but they are hard to find.

Here's a picture of the subaru AWD Set up:

http://www.leoidea.com/wp-content/up...awd_250-op.jpg

The engine and transmission are located as if they were in a RWD car. The front differential, transmission, and rear transfer case are all a single unit. Then a regular drive shaft and rear differential (R160) to the back.

So why does the clutch pack burn up if you coast in neutral? Doesn't it run in an oil bath?

I think its the centre diff or something which lunches itself if only one set of wheels (front or rear) is turning. Similar advice is never to tow a Subaru AWD with wheels on the ground - i.e. use a flatbed.

There is a 2WD version of the Imprezza so the gearbox could be swapped leaving the rear shafts in place and then drive that assembly seperately as shadetree tapped.

Starting to get expensive though.

But it's 200A to START a cold engine, not to keep a hot engine spinning at 500RPM. Maybe a better place to start with this math would be to measure engine braking on flat land in low gear, or to consider your gph in neutral at 2000 RPM.

Car-part.com tells me you can get a tranny for $150, but then you need the shift linkage, pedal set, maybe some wiring... not an easy job.

Iirc, I've read about people converting from AWD to FWD by welding shut the center differential. But this is probably all off-topic, right?

Motor, controller, instruments ordered!

Yeah, I don't want to get into a lot of fabricating if I don't have to. And I have no idea what kind of increase this is going to show. My best guess is the car is going to drive like it's always going downhill. Which shows me around 100 mpg. As the speed gets higher, the rpms in the motor get higher too and it cancels each other out. But I'll have proper gearing at least!

Robert: I've heard the opposite, people weld their center diff and get a RWD drift car. The EA (80's) Subies might be possible to do something like this, since they have a real transfer case and selectable FWD/4WD/LO

Don't forget that a starter is a high-torque low-efficiency device as well; most of that 200 amps goes to heat, which is why you burn up the starter if you run it for more than a couple of minutes at a time.

It was offered as a swag, but I offer my gph readings from my 1.9 liter saturn warmed up in neutral if you would like to try to make sense out of them:
RPM GPH
1000 0.35
2000 0.65
3000 0.80
4000 1.02

Here's the bsfc chart if a correction is in order. Dunno what to use for load or even if it is constant. Maybe just go with 15.6Nm, though that doesn't explain the non-linearity of the readings (they should be more evenly spaced if the load is 15.6 looking at the chart at these rpm) Image:Saturn 99 1.9l dohc bsfc.jpg - EcoModder

Since you will be using the motor to assist it would probably work best to have the controller base the output on Load and RPM. That way if cruising at 60mph on flat ground then you hit a hill and the load normally would go up say 40% the controller sees the increase in load and increases the output of the assist motor reducing the overall load on the motor making it easier to stay at speed with out adding throttle.

That's the plan! Except it's going to be much simpler than that:

I'm simply going to have 2 independent throttles. I'll control the electric motor with my hand and the regular gas engine with my foot.

72Volt system is what I'm going for now, after talking to the motor people. I might change for a smaller battery to make mounting them easier.

Anywho, had a few minutes extra today and decided to mock up the motor.

http://ecomodder.com/forum/attachmen...1&d=1280174081

http://ecomodder.com/forum/attachmen...1&d=1280174081

I apologize for the crappy mock up, but look it has the motor written on it! :thumbup:

Anywho, it looks like it will fit with some work. I'm going to have to move the power steering reservoir for sure. It seems on some subaru's it's located on top of the steering pump.

http://www.ludicrous-speed.com/g2/ma...g2_itemId=5264

Which is what I'll be going for. Hopefully I can fit the stock one in place, if not I guess I'll have to go to the junkyard and find one that fits.

The ABS Pump/lines seems to be less of a problem. I might need to move it, I might not. Depending on how big the bracketing is for the motor. If I do have to move it, the plan is to simply copy what others have done and shove the pump into the fender:

http://i131.photobucket.com/albums/p...d/IMG_3304.jpg

Man is it a nice day to be working on a piece of lego.

Anywho, the engine redline is 6000 RPM, and the motor is 7500 RPM. Which means I need a 12:15 or 1:1.25 ratio?

they changed around the power steering between 99 and 00. I think they would be easy to swap, but the newer ones turn off as you go faster, so you might just want to try and relocate the holding tank, or if you don't mined driving with out PS for a few days I'll Fed Ex you mine in trade for yours.

Thanks Doc, I'll take that into consideration if I can't find something. Although I also have my girls forester which has that style reservoir, which I might just trade with her if she says it's alright. Looks dead simple to move anyway it goes.

I also found info tonight about the GM B.A.S. Hybrid which is basically a really big alternator that can start the motor/regen. Well that's a lot of confidence with me knowing the belt should be able to handle the power! And hey, if my starter goes I'll have a redundant one wouldn't I? I could just spin the motor up with the AC-12.

In fact, I think I'll have a lot of redundant things on the car with this system in place. I could undoubtedly run a 12V converter in place of the starting battery, the alternator would also be mostly useless. Along with the starter too. Oh well, that's stuff to worry about once the system is operational right?

The nice thing about a redundancy is something being a bit more fail safe. And i suspect the car would be "happier" with its OEM alterator in place.

just my .02.:D

Brucey do you have any other info on the B.A.S system I'm wondering how exactly that did it as they have the same car with out it and and option with it. If I find anything use full I will let you know.

Geneva '08: GM announces new second-generation mild hybrid system &mdash; Autoblog Green

That's the best explanation I've seen. Looks very very simple and easily adapted to any car.

Ok, so had about an hour to fiddle with my engine bay today. I looked into relocating the power steering reservoir and can't find an easy location. I'm considering simply pushing it all the way back of the engine bay, near the air filter box.

I'm also considering swapping out mine with my girlfriends forester, since we both have the EJ25 SOHC, it should bolt up. This would be less ghetto but a lot more time intensive.

OK, so my original ideas of using T105 batteries might be questioned.

I really would like the entire battery pack fit into the area shown earlier in this thread, as to keep the usefulness of the trunk still. But fitting 12 of the T105's into the car might be a bit of a hassle. I still would like to go for lead, since it's cheap. And eventually switch up to lithium of some sort.

Any ideas of from anyone for a battery that can handle 400Amps regularly? I'll be calling my local golf cart guy tomorrow.

I also looked into the bracket itself. I found a design that would suit both the cars engine, and the electric motor.

http://i760.photobucket.com/albums/x...e/IMG_8852.jpg

It attaches on the front of the motor via the Power steering pump bolts and a secondary bracket attached to the intake manifold. I might add a few extra braces on mine though.


Then dug up some diagrams of a smaller bracket for a different set up:

2000 Subaru Impreza 2.5RSC Build Diagrams - Ludicrous-Speed

and used the dimensions given between the bolt holes on SC5 as a measurement, and got these rough dimensions:

http://ecomodder.com/forum/attachmen...1&d=1280911096

And started digging in the scrap pile.

As it happened, I have a 10" by 15" piece of 1/4 6061 aluminum. So I think the first bracket should be starting to come together soon. I really would prefer steel for this, but we'll see if this is good enough. I also can't finish the motor until the bracket arrives, for final fitment. Then it's just a matter of finding the pulleys and tighten'er down! :thumbup:

PS: All information is found via google and owns to their owners. GG