Alternator delete with regen braking modification for better MPG

[MetroMPG]

Increasing wind resistance kind of defeats the purpose of this project.

Smiley face (maybe should have been wink face).

[Daox]

Okay. Time to finish up phase one of this project. Now that the alternator disable circuit is in and working like it should, I need a way to recharge the battery. This means a 110V charger that I plug in when I get home as Loren suggested. I happen to have the one I used on my last car. Its a Soneil 5A smart charger. You don't have to press any buttons on it to get things started, just plug it in and it charges. Once it is done charging it float / maintain charges the battery. So, when I get home at night, I plug in and when I leave the next morning I unplug and go.





To make things more convenient, I picked up one of these flange mounted outlets.





I drilled a hole in the front bumper cover hear the driver's side light to mount it.





And the outlet gets fished through.





A few more screws to hold the flange in place, and its installed.







Now, to install the charger. I want the charger inside the cabin to keep it out of the elements. This means passing the power cord, and the charging wires through the firewall. So, I found the main rubber grommet that the wire harness passes through, and I poked a hole in it. Then, I took a metal rod and shoved it through, taped my wires to it, and pulled them back through.







That is where the progress ended for the day as it started raining out. However, I did get a few shots that show how the plug looks and works. I think it blends in nicely and it really is quite convenient.

[Loren]

A bit late for this thought, but you could have accomplished the same charging with much less weight added to the car (and a simpler installation) by just running a pair of heavy gauge wires from the battery to the bumper. Use some kind of either RV, trailer or welding connector to connect the DC to your now EXTERNAL charger.

You've got my wheels turning now. From my personal performance perspective (which is autocross, where I need max power available for maybe 60 seconds at a time), cutting the alternator out, perhaps with a switch that's on a timer (so I don't forget to turn it back on), would potentially free up some power.

Did you verify whether or not the ECU cuts the alternator output at full throttle? If it does, then it wouldn't be worth doing. But, if the alternator is still charging at full throttle... there's some power I could free up. And for not a lot of money.

[Daox]

In my testing (which was only one 'pull'), the alternator didn't turn off or even turn down at all under WOT. Here is a picture of my scangauge. LOD is engine load. I've never seen it hit 100 on any car, so I assume 99 is WOT.

[Loren]

Wish I could remember what I did with my Scangauge. It's either buried in a box somewhere, or I loaned it to somebody and never got it back.

[Daox]

Disaster struck last night. My dc-dc converter got toasted I am pretty sure. The input voltage range for it is only 10.8-13.2V. Well, I think my switch (which actuates with almost no physical input) got bumped or jostled and the alternator turned on bumping the voltage up to 14.4V. Then, it got turned back off which exposed the dc-dc converter to more than 13.2V as the battery voltage slowly fell. And, while it can take a 100ms spike at 18V (which I had hoped would be enough), it stopped working. So, I am thinking that I have two choices:

1) Create a protection circuit so the dc-dc converter never sees above 13.2V.

2) Use a different dc-dc converter.

I'm partial to #1 because I bought two dc-dc converters just in case I fried one. However, I'm thinking #2 may be a better option. A voltage divider will not work for the spread of voltages I'm looking at. I did the calculations. I'm not aware of any other simple circuit that can keep the voltage to the dc-dc converter in the necessary range. I'm not looking to make this complex.

On the upside, this would have happened anyway once I figured out the regen side of things because that would have been intentionally turning the alternator on and off. So, the dc-dc converter has to be able to handle this scenario if I am going to go through with that phase of the modification.

[timw4mail]

Disaster struck last night. My dc-dc converter got toasted I am pretty sure. The input voltage range for it is only 10.8-13.2V. Well, I think my switch (which actuates with almost no physical input) got bumped or jostled and the alternator turned on bumping the voltage up to 14.4V. Then, it got turned back off which exposed the dc-dc converter to more than 13.2V as the battery voltage slowly fell. And, while it can take a 100ms spike at 18V (which I had hoped would be enough), it stopped working. So, I am thinking that I have two choices:

1) Create a protection circuit so the dc-dc converter never sees above 13.2V.

2) Use a different dc-dc converter.

I'm partial to #1 because I bought two dc-dc converters just in case I fried one. However, I'm thinking #2 may be a better option. I'm not aware of any simple circuit that can keep the voltage to the dc-dc converter in the necessary range. I'm not looking to make this complex.

On the upside, this would have happened anyway once I figured out the regen side of things because that would have been intentionally turning the alternator on and off. So, the dc-dc converter has to be able to handle this scenario if I am going to go through with that phase of the modification.

So, better to find out now, rather than later?

The more I learn about cars, the more amazing it is how infrequently they break, and how long they last.

There's got to be some sturdy circuitry to be able to handle the voltage variance of the battery/alternator combination.

[MetroMPG]

Disaster struck last night.

Scared me when I read that!

Not as much of a disaster as I thought.

[Daox]

Haha, nothing so bad. Just killed the dc-dc. There aren't any indications of visual destruction. It just doesn't seem to work anymore.

My current thought that would probably be the most robust is to use a linear voltage regulator like a 7805. These are extremely common chips. The one I linked to can handle up to 35V. I would need to go to one that puts out 5V though due to how they work. That means I would also need to get a 5V to 15V dc-dc converter instead of my 12V to 15V converter. However, this would pretty much ensure nothing would fry. That being said, there is one of these built into an arduino which is the programmable micro controller that I'll be using for phase two anyways. So, I wouldn't even need one if I got the new dc-dc converter.

[Loren]

The best long term solution would be to specify a higher-rated DC convertor.

But, since you have another one, a simple series resistor could be used to drop the input voltage to an acceptable level. Just figure what you expect the max input voltage to ever be, and size your resistor accordingly. But, if you drop too much voltage, then your DC convertor would cut out, which would turn the alternator on. (which could be used as a fail-safe feature...)