Homebrewed I-Eloop
 

I am starting this thread to document my efforts to make a homemade I-eloop system for Champagne. The plans thus far;

Research and make electrically engaged clutch to activate the regen cycle on the alternator when decelerating.

Research capacitor bank size necessary to produce enough energy to be effective and realistically beneficial to use as a source of power.

A DC/DC converter will be necessary for this. When it comes to electronics I know enough to get this off the ground but will rely heavily on input and advice from the more experienced members. This will be an all together effort :thumbup:

For logic control I plan on using my Arduino. I would prefer to do this on the cheap and try to reuse my alternator only design the clutch for the current pully. I have axis to machinists through work so I don't think this will be a problem.

Otherwise if this is not feasible for Champagne it will still serve as a very useful learning experience.

I will continually update this as I go and acquire/ design the required components for this system.

Cheers!

I like the idea and think it could somewhat work if the components were carefully selected and engineered, however the cost and complexity might not make it worth it.

If it were me, I'd instead focus on programming the alternator to electronically shutdown during normal engine operation, and startup during DFCO. Then I would select an appropriately sized LiFePO4 to replace the inefficient lead acid battery, trying to locate it somewhere within the passenger compartment or under a seat (for better temperature control). You could program the Arduino to re-engage the alternator if the voltage drops below some set threshold.

The trick would be keeping the battery from frying, which might be where a supercap and DC/DC converter might come in to act as a buffer.

The cruze alternator uses RVC (regulated voltage control) technology already to improve fuel economy by reducing voltage being sent to the battery when the battery is fully charged. So instead of producing 14V continuously it will drop down to 12.5V and reduce the pull on the engine in order to provide power to the vehicles electronics. I guess it could be considered charging cycle on and off. Once a the battery drops to a pre-determined level of charge to alternator voltage will increase back to 14v in order to recharge the battery. The technology is already similar to I-eloop in reducing alternator load. I still think however that the system can be further improved using the I-eloop.

The alternator also enters a "batter recharge" mode when decelerating (turns up to 14v). This explains why the I-eloop is more efficient as the alternator will vary the voltage to smoothly fill the capacitor bank. I am more curious now to figure out the recharge efficiency of the recharge cycle on the cruze alternator.

This will be the starting point:

The alternator max recharge voltage: I have seen this as high as 14.4 on the DIC.
Going forward will measure battery voltage realtime and see how efficient the "recharge" cycle is on the alternator when decelerating.

This will then be compared to using the same recharge voltage of 14V to attempt a charge up on a capacitor bank. The capacitor bank charge will then be compared to the voltage gain on the batter. The energy stored will then be compared in Joules.

Comments, and advice are appreciated.

This is also a great idea to be explored. The supercap bank would have to be sized appropriately, even over sized to protect the battery. Could a bleed off resistor be used as well in this case?

Do you need the clutch or can you disable the alternator by disconnecting the field windings?

If you are using a capacitor as a buffer can you use a 24V alternator? Many alternators have 24V and 12V variants within the same basic design. Capacitor charge storage is increased with increased voltage.

Check the power requirements. There is only brief period available for energy recapture. To make it effective the power requirement is likely to be quite high. Higher voltage will help the current requirement. A capacitor bank is likely to be more effective than a chemical cell battery where power requirement, in and out, is the important criteria.

Mmmm I like your intention to work on the Cruze but I think you're going about this the wrong way. The logic behind the alternator is actually pretty complicated, not just "ON if voltage falls below X." For example, the alternator is automatically ON if the headdlights are on. There was a thread about it on Cruzetalk a couple days ago.

I agree with ^, why do you need a clutch? I think a better way to go about it would be:
1. Replace the Pb-acid battery with lithium ion.
2. Replace your lights with LED.
3. Set up a system to plug in and charge your battery at home.
4. THEN, set up a switch to manually disable recharge while you're driving.

No clutch needed.

could you please post a link to the thread on cruzetalk

Ideally I would like to use a 24V setup to do as you mentioned. The mazda I-eloop system uses a variable 12/25v alternator to regulate the charge build up in the capacitor bank. I know the logic behind this will be a challenge but I do think it is quite possible.

That being said from my understanding (which could be wrong) most newer cars come with variable alternators already. I could monitor this by using a multimeter to see what voltage is being produced during the recharge of the battery. I know it says on GM's website that the alternator produces 14v during the charge cycle and 12.5 in the normal running cycle but, today while driving I watched the voltage on my battery go up to 15.1v on the DIC. I wonder if the cruze alternator is already capable of 25v output.

Found this on cruzetalk, I think this is what ME_Andy was talking about. Other than this all I could find was people wanting to keep the alternator charging to feed their power hungry aftermarket sound systems. This information is the same that is on GM's website.

I had been thinking that this might just be a side effect of the deceleration fuel cut off (DFCO) system since the car wouldn't need to be firing the cylinders while fuel wasn't being supplied to the engine but then I found this article on the Cruze's Regulated Voltage Control (RVC).

Chevy Cruze regulates voltage to boost fuel economy — Autoblog Green

This article says that the alternator normally provides reduced voltage during normal driving to reduce load on the engine and it implies that the alternator engages a bit more than usual when you are decelerating and no fuel is being supplied to the engine (due to DFCO). The alternator reclaims some kinetic energy to keep the car's electrical systems running and charge the battery. Kind of cool I guess

I've messed about with this kind of alt on UFI and here's what I found:

1. The alternator monitors charge acceptance, not just voltage (voltage can't tell you much frankly). If you fit a LiFe or supercap, you'll change charge acceptance and the alternator will become confused. I often had to stop and reset the system as it would go into safe mode (constant 14.0V). S/S was never going to work as again, charge acceptance was too high as judged by the ECU.

2. Disconnecting the alt is all but pointless. Essentially (assuming you have a serpentine belt), it's already free spinning much of the time so removing it and fitting an idler pulley won't help.

3. Charge the battery every night. You'll get a solid 5% gain as essentially the alt is now off because the battery is full. It will still ramp up on overrun for some free charging.

Battery volts

(~5th post)

This probably falls under TMI, but here it is for those that might be interested.


2014 Chevrolet Cruze 2.0L Eng Diesel

Charging System Operation

The purpose of the charging system is to maintain the battery charge and vehicle loads. There are 6 modes of operation and they include:

Battery Sulfation Mode
Charge Mode
Fuel Economy Mode
Headlamp Mode
Start Up Mode
Voltage Reduction Mode

The engine control module (ECM) controls the generator through the generator turn ON signal circuit. The ECM monitors the generator performance though the generator field duty cycle signal circuit. The signal is a pulse width modulation (PWM) signal of 128 Hz with a duty cycle of 0-100 percent. Normal duty cycle is between 5-95 percent. Between 0-5 percent and 95-100 percent are for diagnostic purposes. The following table shows the commanded duty cycle and output voltage of the generator:
Commanded Duty Cycle Generator Output Voltage
10% 11 V
20% 11.56 V
30% 12.12 V
40% 12.68 V
50% 13.25 V
60% 13.81 V
70% 14.37 V
80% 14.94 V
90% 15.5 V
The generator provides a feedback signal of the generator voltage output through the generator field duty cycle signal circuit to the ECM. This information is sent to the body control module (BCM). The signal is PWM signal of 128 Hz with a duty cycle of 0-100 percent. Normal duty cycle is between 5-99 percent. Between 0-5 percent and 100 percent are for diagnostic purposes.
Battery Sulfation Mode

The BCM will enter this mode when the interpreted generator output voltage is less than 13.2 V for 45 minutes. When this condition exists the BCM will enter Charge Mode for 2-3 minutes. The BCM will then determine which mode to enter depending on voltage requirements.

Charge Mode

The BCM will enter Charge Mode when ever one of the following conditions are met.

The wipers are ON for more than 3 seconds.
GMLAN (Climate Control Voltage Boost Mode Request) is true, as sensed by the HVAC control head. High speed cooling fan, rear defogger and HVAC high speed blower operation can cause the BCM to enter the Charge Mode.
The estimated battery temperature is less than 0°C (32°F).
Battery State of Charge is less than 80 percent.
Vehicle speed is greater than 145 km/h (90 mph)
Current sensor fault exists.
System voltage was determined to be below 12.56 V

When any one of these conditions is met, the system will set targeted generator output voltage to a charging voltage between 13.9-15.5 V, depending on the battery state of charge and estimated battery temperature.

Fuel Economy Mode

The BCM will enter Fuel Economy Mode when the estimated battery temperature is at least 0°C (32°F) but less than or equal to 80°C (176°F), the calculated battery current is less than 15 amperes and greater than -8 amperes and the battery state-of-charge is greater than or equal to 80 percent. Its targeted generator output voltage is the open circuit voltage of the battery and can be between 12.5-13.1 V. The BCM will exit this mode and enter Charge Mode when any of the conditions described above are present.

Headlamp Mode

The BCM will enter Headlamp Mode when ever the headlamps are ON (high or low beams). Voltage will be regulated between 13.9-14.5 V.

Start Up Mode

When the engine is started the BCM sets a targeted generator output voltage of 14.5 V for 30 seconds.

Voltage Reduction Mode

The BCM will enter Voltage Reduction Mode when the calculated ambient air temperature is above 0°C (32°F). The calculated battery current is less than 1 ampere and greater than -7 amperes and the generator field duty cycle is less than 99 percent. Its targeted generator output voltage is 12.9 V. The BCM will exit this mode once the criteria are met for Charge Mode.

Thanks for all the information posted. This appears to be a much more in depth project. I like the idea of charging the battery overnight to reduce the alternator charge cycle(s).

I will research further and revisit with results. Thanks everyone for all your help. :thumbup:

What if supercaps are constantly charged to 14.8v with an external battery.

Also where is battery temperature measured?

Can the bcm signals be intercepted on the canbus? Or some other wire?