i think once the ELD is bypassed and the PCM is tricked, the voltage will be a steady 14.4VDC.

 

So i have a 96 accord and i just tapped in the toggle using-1. Cut ELD green/red wire as in your circuit.
2. The half of that wire coming from the PCM goes to the POLE of the toggle switch.
3. The other half goes to one of the THROWS of the switch; the POLE would be switched to this THROW when I want to ELD to work normally.
4. The other THROW goes through an 820-ohm resistor to the black ELD ground wire at the plug; switching to this THROW would bypass the ELD and cause the alternator to turn on and charge the battery all the time.- as the guide. So do I plug the pig tail back into the box? Also if I only wired in the toggle will it still work? I ask because it doesn't seem like it is. I would like to have a car that's not running on only battery. If I could get a bit more direction that would be awesome Thx guys!!!!

 

I have an Acura TSX and found this forum from a search on ELDs.

There isn't much info available on the subject, but I am looking for a way to disable the alternator output with a switch, while maintaining the ability to re-enable by switching back.

I would like the ability to run on battery only, which I realize is the exact opposite of the point of this thread, but should be achievable by utilizing some of the same methods.

Based on the article explaining the ELD that Keep Hope Alive shared, it seems there are 2 ways to disable the alternator.

1. Supply 5v on the FR circuit tricking the ECM into thinking electrical demand is zero.

2. Ground the C circuit output.

Are either of these methods correct if I want NO alternator output? Do I need a resistor if I ground the C circuit output?

Here is the Acura schematic

 

Although it can be detrimental to the battery if done continuously and may cause other electrical gremlins, if there is no power/voltage at the IG wire (Blk/Yel), then the alternator/regulator assembly is not turned on. The IG wire supplies the ignition input that turns on the alternator/regulator assembly; so, if a switch was installed in-line with that wire, it shoud effectively stop the alternator from charging.

Some info.
Honda's utilizes a dual mode charging system to increase fuel efficiency and reduce drag on the engine on start-up. The ECM/PCM determines charging based on info. from the ELD. During heavy load, the ECM/PCM can set charging voltage for high output (~14V - 15V). During light load and start-up, the ECM/PCM sets charging voltage for low output (~12 - 13V).

Most previous generation Hondas had alternator/voltage regulators which utilize five terminal wires: Ignition (IG), Control (C), Field Reference (FR), Battery (B), and Lamp (L). The wires between the alternator's voltage regulator and PCM are the C, FR, and L wires. The ECM/PCM can control charge modes (high or low output).

 

Thank you for the quick reply and detailed explanation Redbull. Do you know if switching the IG circuit off will cause a CEL, or any other strange behavior besides disabling the alternator?

I'm on another forum called Ecomodder.com, and the objective there is to improve fuel economy of the vehicles we choose to drive. From what I have read, disabling the alternator and allowing it to freewheel can improve fuel economy by an average of 5%. While that is not a lot, over the course of the 200,000 miles I plan to put on the vehicle, it amounts to about $1,150 savings in gas.

My plan is to eliminate the heavy lead-acid battery and replace it with a lighter weight LiFePO4 battery that can tolerate the deeper discharge without being damaged. I would then charge using a battery charger at home.

If done correctly, the battery should last the life of the vehicle, improve fuel economy, and provide slightly better performance by reducing weight and eliminating the drag placed on the engine by the alternator.

 

You may get a CEL. I don't know for sure whether you may get electrical gremlins. The reason I mentioned it previously is because your TSX and later model Honda/Acuras relies a lot more on a multiplex control system for communications of data. You can always pull the fuse to the IG wire for your car and see what happens.

This other thread is where I help someone with an earlier model Accord, which has less items running through its multiplex control system that had a blown fuse for the IG wire, which causes a CEL and a no charge issue.

https://www.hondaaccordforum.com/for...lved%5D-59976/

 

interesting approach.

you will need to run the alt when the headlights are on, and you will need a volt meter to turn the alt on when battery voltage drops below 12V. even if the battery can handle deeper discharge, the car's electronics won't function properly below 11V.

your ability to hypermile with the use of the gas and use of neutral will make a much larger difference than the alternator.

 

I applaud you for keeping the bigger picture in perspective. You are absolutely correct in pointing out that driving habits will contribute a much larger difference in fuel economy than modding the vehicle. After all, Honda has already gathered the brightest engineers they can to strike an optimal balance of performance, economy, and price.

Here is my fuel economy in an unmodified TSX utilizing some hypermiling techniques, including brisk acceleration.



Regarding the use of the alternator; I will be running an appropriately sized LiFePO4 battery, which has a slightly higher nominal voltage of 13.3v compared to the 12.5v of a lead acid battery. Much of that capacity is usable before the voltage drops below 12v. I will also be combining the battery with a supercapacitor "battery" that will provide power for large demands for energy, such as starting the vehicle.

I've decided to buy a donor 4-ping alternator wire harness so I can cleanly splice in switches, while leaving the factory wiring pristine so it can be returned to stock.

My design is inspired by this video;

 

i run a six-cell Maxwell BCAP3000 bank in my car and install them in other cars.

they are excellent as a supplement to a decent AGM battery. my alternator was failing my 2001 Accord but i didn't know because the ultracaps were supporting the vehicle. Once i removed the caps it only took a week for the car to shut down from low voltage/poor charging.

my 2014 CVT I4 Accord has a posted 34mpg HWY but at 55mph I can easily achieve 43mpg HWY average over hundreds of miles. the CVT + EcoAssist is a nice combo for hypermiling.

 

...perhaps I should create a new thread since this has taken a large tangent.

"keep_hope_alive"i run a six-cell Maxwell BCAP3000 bank in my car"

Maxwell has a new part out that is 3400 farad and 2.85v. Mouser has them for $68 apiece for a quantity of 5.

I'm tempted to see if I can get away with running 5 in series, which would give me up to 14.25v total. The specs show 3v as the absolute maximum voltage for an individual cell. Running 5 of these in series not only increases capacity due to the higher rating, but eliminating the 6th capacitor increases the bank effectiveness.

6x 3000 farad capacitors in series gives an effective capacitance of 500 farads.

5x 3400 farad capacitors in series gives an effective capacitance of 680; a 36% increase.

I believe I can run my 1998 Dodge/Cummins diesel on capacitors alone.

I'm already running my CBR600 F4i motorcycle on a bank of 400 farad capacitors, with no other battery.


"my alternator was failing my 2001 Accord but i didn't know because the ultracaps were supporting the vehicle."

Do you think ultracaps put extra strain on alternators due to their ability to absorb high levels of current, presenting very little resistance to the alternators attempt to charge? In other words, do you believe your alt had a shorter life due to the ultracaps?