Belt Alternator System (BAS) hybrid - general discussion thread
 

At the suggestion of Green Hornet on another thread yesterday, I am starting this thread as a place on EM to collect some specs on GM's BAS mild-hybrid. I am putting it in the "hybrids" subforum, but maybe it will belong in the ecomodding central subforum. Depends on how/if EM members participate.

The system's advantage to GM has been that it is relatively cheap to implement, since the electric motor can replace the alternator and starter and fits on the engine, belted to the crank pulley. For a moderately ambitious modder with fabrication skills, the advantage of such a system is the same. It is *relatively* easy to implement as a mod on a standard ICE.

I searched EM and found mentions of the BAS but no thread devoted to it. I'll come back to this OP to edit it for corrections.

There have apparently been two generations of this system, with the first being launched in 2007 and the second in 2012.

According to a Hendon Media Group article, a the system has five major components:

1) An electric motor / generator. AC current from the motor / generator is converted to DC current to charge the batteries, and vice versa.
2) A coolant-cooled power electronics that controls the motor / generator and provides 12 volts to the vehicle’s conventional battery.
3) A nickel metal hydride battery pack capable of 10 kW of power.
4) A separate engine-control module with Hybrid Supervisory Software to manage both the gas engine and hybrid system.
5) A different engine accessory drive with a dual tensioner assembly and aramid cord belt. This belt transfers torque to the gas engine from the electric motor for starting and acceleration, and torque from the engine to the motor to generate electricity.

And there is a more detailed and longer description from "Under Hood Service." Here is a key section describing the functions:

"The BAS alternator’s output is controlled by two modules: the main generator control module, and an auxiliary control module. In normal driving mode, the generator control module converts the alternator’s three-phase, 36-volt alternating current (AC) output to 36 volts direct current (DC) to keep the hybrid battery charged. In start/stop mode, the generator module also converts 36 volts DC from the hybrid battery back into 36 volts AC when the BAS unit requires power to restart the engine, or to provide some extra kick when accelerating."

And then these images and charts from around the internet:

http://ecomodder.com/forum/attachmen...1&d=1463891206

http://ecomodder.com/forum/attachmen...1&d=1463891206

http://ecomodder.com/forum/attachmen...1&d=1463891206

http://ecomodder.com/forum/attachmen...1&d=1463891206

http://ecomodder.com/forum/attachmen...1&d=1463891206

http://ecomodder.com/forum/attachmen...1&d=1463891206

http://ecomodder.com/forum/attachmen...1&d=1463891206

Another GM good idea that looked good on paper.
This was from back in the day when GM just thought people wanted a hybrid badge on their vehicle to be cool and didn't actually care about fuel mileage.
If I remember right the real world driving showed the same or less highway milage as the non hybrid and most of the city mileage improvement was attributed to the auto start/stop tech.

But part of that failure would be because nearly all driver would fail to understand how to use the system, and perhaps the system was not optimalized for their either. For example, if I had something like this in my Civic, I would use it heavily in electric only for initial launches from stops, for crawling around parkinglots, for stop/go traffic. And I would use the enhanced regen braking. I rig it for plug in. If I could to those things my FE would improve substantially.

That motor generator GM used looks like it's maybe 1 to 2 horsepower. Pretty much useless for moving a 3000+ vehicle.

Some of the specs I saw claimed it could draw 10kw... so that would be more like 12hp, wouldn't it? EDIT: deleted a misread of the chart.

10kw only very briefly like when restating the main engine.
10kw sustained would undoubtedly smoke it.
Then look at the motors natural environment, a hot 180°F engine compartment making it even more difficult to cool it's self and making usable horsepower even more difficult.

This is a suitable motor that I will be using for a series hybrid project that would work well for a home built BAS system.These are Brushless and over 90% efficient. Use one of these models in conjunction with a sinewave controller and you would be in business. These are powerful, lightweight, inexpensive and can be customized to suit your needs. These are very robust and rugged motors that are also proven and no I am not affiliated with them in any way just know from many others that they are for real.

Brushless Motor Options:

#1. RV-160 Short | REVOLT
#2. RV-160 Pro | REVOLT

Sinewave controller options

#1. KLS7250D,24V-72V,400A,Sinusoidal Brushless Motor Controller - Kelly Controls, LLC
#2. KLS7275D,24V-72V,500A,Sinusoidal Brushless Motor Controller - Kelly Controls, LLC

Now battery options which will depend on how much electric you want if it is for just stop and go traffic and launches then you need for little in KWh less than 1kwhr to put in perspective. The first Honda Insight had less than 1kw in its pack of NiMH batteries. I would go with Lithium Iron Phosphate which are not the lightest most compact lithium batteries but are the safest and easiest to work with in my opinion. If you go with true 20ah 12V batteries then GBS are a good option for price and support. A 48V system would give you 960 watt hrs pretty close to the First Gen Honda Insight but these are Lithium so superior in my opinion. Or you could go 60V which I would recommend and then you are at 1.2 kilowatt hrs. With a larger car this would help a lot. Remember that the heavier the vehicle the larger system you need. More volts is more efficient. The Honda Insight first Gen used a 144V system. There are a ton of battery options available the first and most important thing to decide is priority like launching, stop and go etc then appropriate voltage to make it happen. Then you can go from there.

#1. Elite Power Solutions

http:// http://gmauthority.com/blog/...k-engine-1.jpg

M 2.4 Liter I4 Ecotec Hybrid LUK Engine

The LUK is a hybrid engine system produced by General Motors for compact, midsize, and full-size vehicles. Displacing 2.4 liters in an I4 configuration, the LUK is part of the Ecotec engine family. It is essentially the LEA Ecotec but modified for GM’s Belt-Alternator Starter (BAS) mild-hybrid drivetrain. It is available on the Buick Regal eAssist and LaCrosse eAssist as well as on the Chevrolet Malibu and Impala.

Overview
Specifications
Vehicle Applications
Pictures

The Ecotec 2.4L LUK uses a state-of-the-art lithium-ion battery system and electric motor-generator to enable regenerative braking capability to improve fuel economy by an estimated 25 percent. The engine is based on the proven Ecotec 2.4L engine, but with features to support the eAssist system.

Engine highlights:

eAssist System: the eAssist system uses power stored in an advanced, 115V lithium-ion battery and channels it to a 15-kW motor generator to provide an electrical boost in various driving scenarios, optimizing engine and transmission operation and increasing fuel economy through:
Regenerative braking, which provides up to 15 kW of electricity to charge the battery
Providing up to 11 kW (15 hp) of electric power assistance during acceleration
Automatic engine shut-off when the vehicle is stopped
Aggressive fuel cut-off during deceleration down to zero vehicle speed, enabled by the torque smoothing provided by the motor-generator unit
Intelligent charge/discharge of the high-voltage battery.
Engine Block: the Ecotec 2.4L’s sand-cast cylinder provides excellent structural support, as well as enabling greater control of noise, vibration and harshness. The main bearing bulkheads, which support the crank bearing, as well as the cylinder bore walls, have been significantly strengthened to support increased engine loads.
Aluminum Pistons with Jet-Spray Cooling: the Ecotec 2.4L’s pistons use lightweight aluminum pistons, for less reciprocating mass inside the engine that enhances efficiency, decreases vibration and bolsters the feeling of performance as rpm increases. Each piston has its own directed jet that sprays oil toward its skirt, coating its underside and the cylinder wall with an additional layer of lubricant. The extra lubrication cools the pistons, reducing friction and operational noise, while also bolstering the engine’s durability.
Cylinder Head: the Ecotec 2.4L has a SPM 319 aluminum cylinder head that is cast with advanced semi-permanent mold technology. This provides excellent strength, reduced machining and optimal port flow. The cylinder head is designed specifically for direct injection into each combustion chamber and includes premium valve seat, valve guide and valve materials. The cylinder head also has integral cast oil passages that feed a set of internal oil control valves that activate cam phasers, enabling variable valve timing.
DOHC with Continuously Variable Valve Timing: overhead cams are the most direct, efficient means of operating the valves, while four valves per cylinder increase airflow in and out of the engine. This arrangement is integrated on the Ecotec 2.4L’s lightweight aluminum cylinder head. Both the intake and exhaust cams have hydraulically operated vane-type phasers that are managed by a solenoid and directed by the engine control module (ECM).
Direct Injection: direct injection moves the point where fuel feeds into an engine closer to the point where it ignites, enabling greater combustion efficiency. Direct injection also reduces emissions, particularly cold-start emissions, by about 25 percent. With direct injection, the higher compression ratio is possible because of a cooling effect as the injected fuel vaporizes in the combustion chamber. This reduces the charge temperature and lessens the likelihood of spark knock. The direct injection fuel injectors have been developed to withstand the greater heat and pressure inside the combustion chamber and also feature multiple outlets for best injection control.
Cam-Driven High-Pressure Fuel Pump: a high-pressure, cam-driven pump provides the fuel pressure required of the direct injection system in the Ecotec 2.4L. The engine-mounted fuel pump is augmented by a conventional electrically operated supply pump in the fuel tank.


Here is a link to read more = http://gmauthority.com/blog/gm/gm-engines/luk/

Notice how GM has now gone to Lithium at 115V. Also notice that the E-motor is 11kw.

These are the main differences from the 1st gen BAS to the 2nd gen BAS.

The 2nd gen now uses Lithium vs the NiMH and you know have a more powerful E-motor up from 5kw to 15kw. Utilizing a larger more powerful 15kw motor gives it a practical E-boost that can be used in a more sustained manner. While 5kw was a good start it was no where close to what was truly needed for a 3,000lb vehicle. Another strong distinction is the increased voltage 115V is way more efficient than the 36V they used in the 1st gen system.

The system has its own cooling, right? The first generation had it's own water pump, separate from the engine, so that the system would be cooled even in start/stop mode. So you think any such system would require that? Seems like a DIY without some cooling system would get mighty hot, as Oilpan4 says above. A separate cooling system really increases the complexity and cost a bit, no?

Concept-checking question: How is this system supposed to improve fuel economy?

Is this system more efficient at generating 12v than a traditional alternator?

I could also see recapturing a little energy with regenerative braking, but most drivers will probably capture 10% or less. It may or may not be worth the added weight.

Auto-stop can help, but it's not necessary to hybridize a car to get this feature.

Honda's mild hybrids downsize the engine while maintaining around the same power to improve economy. I could also see keeping the same engine-size but changing the gearing and using the hybrid motor to prevent downshifts in order to help economy, but simply adding a motor/generator to an existing engine/transmission should do very little for either city or highway driving.

This system improves fuel economy in a number of ways.

#1. Stop/Start capability which eliminates idling time prone to non hybrid cars.

#2. Used for low speed short distance driving whenever you can turn off the ICE and utilize an electric motor for propulsion you will be more efficient. A Gas engine at its best is 28% efficient vs an BLDC electric motor at over 90% efficiency. This type of motor has only 1 moving part compare that to an ICE. Then factor in the environmental aspect and pollution. There are other reasons why an electric motor makes more sense. ICE vehicles have there place but the vast majority of people living in and around Metro areas could absolutely do away with them completely.

#3. BLDC motors have the ability with the correct motor controller to utilize regenerative breaking. However without using ultracaps for harvesting this energy you will not gain very much back into your batteries. If ultracaps are used then you can capture upwards of 50% which then starts to get more attractive.

Honda could have downsized the engine even further to a .6L powerplant that they use in there Kei cars if they wanted to turbocharge the gas engine. Along with a little more capable lithium pack and E-motor you would have an extremely frugal Insight. Or better yet take an AC20 motor attach to manual transmission with 144V Curtis Controller and then use a very small like 200cc or less gas powered genset and you have a very fuel efficient set up for urban areas.

Adding a motor/generator to an existing engine if done correctly can make substantial improvements to fuel economy. There are a lot of factors however that play into it which also make it difficult for the average Joe to get correct. Car engineers have trouble getting it correct and they spend all day trying to figure it out and trying to find that winning combination. Can an average Joe do it? Yes it has been done with varied degrees of success.

Hybrid systems will be standard equipment with in the next 30 years due to emissions standards. They will have to find creative ways to downsize ICE without sacrificing power to help meet emissions standards. The E-motor is the best answer to this problem.

GH

I don't see how liquid is going to be used to cool the stator windings. Be better off ducting in cool out side air.

1) Other manufacturers have stop-start systems that don't require hybridizing the car; it's simply a matter of having a more robust starter.

2) Ultimately, that energy being used by the electric motor comes from the 28% efficient gasoline engine, but it needs the additional conversion of mechanical to electrical, storage in a battery, then back to mechanical energy, which is somewhat lossy. I'm not saying driving all-electric at low-speeds is a bad idea (quite the opposite), just that I'm skeptical of the viability of a belt drive motor that must still spin the engine's crankshaft as a very good way of doing it.

3) Regenerative braking that captures fewer percent of your kinetic energy than is added by additional mass to the vehicle is counterproductive. I'm not saying it does, but this is a factor.

A high-revving 0.6L would almost certainly deliver worse economy than the current 1.0L lean burn engine in the Insight. Below a certain point, downsizing an engine starts to have the opposite effect on economy, because you start needing to rev it up to make the same power. I'm not sure where boost falls into this, but if it's necessary to run rich when in boost (is it?) that would also be a factor. Cruising along at 70mph in 5th gear, the Insight has virtually no power to spare, it's nearly WoT, and when cruising at lower speeds, it leans out the AFR to is lean as 25:1 to keep the throttle plate almost completely open.

I'm not saying a smaller displacement motor couldn't work, just that you need to be mindful of avoiding revving it up.

I agree that hybrid systems will be standard, but they're probably going to be bolted onto downsized motors and allow for the engine to be decoupled from the drivetrain, rather than keeping the same displacement and needing to continue pumping air through the cylinders while the electric motor is providing power.

BAS system in operation (Saturn Vue)
 

Here's a pretty good video the BAS system being tested in a shop. You can hear them testing different scenarios as you watch the belts turn. But looking at the comments, it seems like the system is kind of glitchy. It seems like the tensioner allows a lot of slippage on the belt. Seems frustrating to maintain.

https://m.youtube.com/watch?v=uo0ZDg0vq0o

Green Hornet, any updates to your project?

that would be cool if he figured out how to get it working
I would like to have a Super hybrid :D


two hybrids are better then one I have the space in the rear anyways for an extra battery


also would this throw the engine timing off?? as I would be able to connect one of these Directly to the Crank shaft (obviously externally ) where the A/C compressor would normally go "it has a spot for it"

that little motor could help in a V4-deceleration fuel cutoff...... by coasting longer or acceleration boost.... that is where the MPG is weak on the lower speeds 35 or less

Combining that to a CVT, it might be a great way to keep an engine at its best RPM range throughout most of the driving cycles.