are you actually using reverse current into the batteries? or does the circuit just reduce current for a second to allow the batteries to recover?

if you are actually using charging current into the batteries (which i doubt) i would be interested to see the effects, some forms of charging essentially use the opposite to this.

If its the latter then wouldn't a current limit be a better option?

Its questionable whether this is going to have a positive effect on your batteries, your controller or your drivetrain.

 

When ever the accelerator is pulled back enough and the motor and controller operates in regenerative mode, voltage is returned to the batteries which will help the batteries to recover. The circuit does this for me so that I no longer have to take my foot off the pedal to rest the battery. I used to have to do this to get up speed on a steep hill. I guess the best answer to your question is that both events take place. The battery gets a reverse current at times and the battery will get a rest at times.

An easy experiment to demonstrate the effect of resting a battery is to take an essentially dead battery that will not turn a motor. Next charge a large capacitor. Next connect the motor to the battery and parallel capacitor. The motor will run for a short time but, it will start up at full speed. Repeat the cycle over and over until finally the battery is truly dead. Now start with a fresh battery and try this all over again, still connecting the motor to the battery and the cap for a few seconds at a time. The fresh battery will last a very long time.
Now, put a flywheel on the motor and do this all again. Record your results. Tell everyone. No one will believe you. Now put it all in a car and drive it. People will tell you to buy a real car that burns gas. Amazing! LOL.

A current limiter will not help you to accelerate in pulses or to lift the voltage sag. The limiter will limit the performance of the car. A few miles from home, the batteries were weak, I needed to squeeze the juice out of the batteries if I was going to get home without walking. I could only get home by letting up on the pedal and then going full out again and then repeat the process. This is how I learned to do this and I did not have to walk home. But, subtle is the operative word here. I would not want the car to be jerky, I want it to coast for a second and then get up and move out, up hills, etc.

 

Hi sir,

What you are experiencing is sensory illusion, similar to optical illusion. There are no real gains in performance over what could be achieved with a steady throttle position reduced from full on. And certainly any regeneration would come at the expense of kinetic energy and be a net loss. Nice try but it won't pass the test of theory or lab.

Regards,

major

 

Motors pull excessive current when under heavy load and when supplied with low voltage. Pulling the accelerator back 25% and allowing the car to coast for a moment is not a huge loss. Making assumptions is not science. You have not performed this experiment in any lab or on the street to make these observations.
To get up a steep hill when the voltage badly sags, you may have to rest the battery. Holding your accelerator at a constant will not do anything but draw excessive current under heavy load which will further pull down the voltage. This will rapidly discharge the battery and you may come to a stop before you reach the top of the hill. To accelerate, you must lift the voltage sag and restore peak operating conditions and restore performance. I am talking about speed. Instead of crawling up hill at a constant but slow pace or even having to stop half way up the hill, I can accelerate up that hill. The hill is not an illusion of any kind nor is the speed of which I can attain.
I have a long list of the things people have told me an electric car can't do.

 

I suggest you not tell me what I have or have not done in the lab, or on the street, or on track, or on the salt. You have no idea. I figured you'd resist reality. I'm not going to argue about it. You will hurt your ceditability if you publish such fairy tales.

 

I suggest you not tell me what I have or have not done in the lab, or on the street, or on track, or on the salt. You have no idea. I figured you'd resist reality. I'm not going to argue about it. You will hurt your ceditability if you publish such fairy tales.

Major, really- Please don't take offense. I only meant to say that you replied to my posts within a very short time. Not enough time to fully examine my circuit, to build it or to test it with an open mind. I have never posted the full schematics either.
Salt? Creditability?
I have put this into use in my own car and have driven it many times. But, I will concede to the fact that it has not been independently tested. It has only been installed in my car and I do publish the fact that I have done so.
I do leave room for doubt. I have labeled it experimental. I am not afraid to try or to fail. Not, afraid to be wrong either. But, I also have never found another solution to the problem. I want to hear it from any expert. Even a proper explanation of voltage sag and what will cause it would be a good start.

I really do have a very long list of the things my car can't do that have been authored in hast by many persons. And, I am always wrong from the very start before anyone even takes the opportunity to examined, to test, to apply the scientific method or ,just simply to ask the very first thing about it. The unproven negative is waiting for us all.

 

I agree the circuit is a waste of time and just uses more energy. You cannot change the relationship of power and regeneration. It is impossible to what what you claim.

 

Your focus is on the regeneration. I only pull back 25% and let the car coast for 1 second while the voltage pops up. If you have a volt meter in your own car and you take your foot off of the accelerator after it has been to the floor, what happens to the battery voltage? I think it recovers? Does anyone see this? This is all I am claiming. This is all the circuit does in this universe. Next push it back to the floor. It will move in any universe.

 

Major, Sunking,

Let me get this straight, this guy built a throttle limiter, and thinks it makes him go up a hill faster?

Wouldn't it just make more sense to have a battery pack that could handle the current to get you up the hill in the first place? Last I checked steady throttle and vehicle speed were ideal for conservation of energy.

 

Major, Sunking,

Let me get this straight, this guy built a throttle limiter, and thinks it makes him go up a hill faster?

Wouldn't it just make more sense to have a battery pack that could handle the current to get you up the hill in the first place? Last I checked steady throttle and vehicle speed were ideal for conservation of energy.

Voltage sag is what reduces your performance and speed. Pressing the throttle (there is no such thing in electric cars) will cause a voltage drop as the current rises. Motors run slow if the voltage is low. On the street you really can't drive at steady throttle. Maybe on a track but, I drive to work on actual roads with stops, turns and potholes. Batteries are heavy and add weight. No matter how big the battery, it will still get weak and the voltage sag is back.
You might read about coasting technology and how that works. You might say it can't

 

Ok Ok I see your perspective. LOL

But hey I want to reduce weight. Add more weight to make this crazy thing fly don't make sense to me. I remove anything heavier than a paper clip.

 

Yep. I love the list also. Here goes--

1. You can't have any room in the trunk for groceries now can you!

Well, I do.

2. You can't pull a boat with that crazy thing! I could pull a small boat but it never could.

3. You can't allow a battery to recover it's voltage because that would violate the laws of thermal dynamics. This is still under discussion.

4. You can't get up to 70mpg and drive on the highway because you would need gasoline for that.

Wrong!

5. Electric cars have a longer tail pipe, I know because I am an expert and I would be offended by the very fairy tale of solar and wind energy. Coal is how electricity is made.

Really?

6. It is a conspiracy and you are on the payroll aren't you? Yes you are! You electric car people are trying to take away my freedoms. Darn Liberal.

Yea I am all of that. So what.

7. You can't go 63 miles with a 140 Ah battery!!!!!!!

Believe what you want. It does!

8 thu 80

Yes the list goes on and on.

 

Now-
tell me about the algorithm used to control "coasting mode" as applied to electric vehicles. Yep- coasting in gear. What is that? Some big engineers with big car companies think it is a way to use less energy and go farther.

I really want to know how this can't work.
anyone?

 

I get what you are saying sirwattsalot.

I have certainly experienced the voltage drop you are describing and also the recovery after a brief pause.

I don't think sirwattsalot is suggesting anything that breaks any laws of physics etc. I also see that the circuit in question doesn't actually "solve" the problem at all. All it does is introduce an automated way to provide the batteries with the break they need to avoid the threshold that triggers the issue. The circuit has the same effect as removing your foot from the pedal every 3.5 seconds. But the circuit is just for convienience so you don't have to think about it. If that is a suitable solution for you then great.

 

Yes and thanks, it works for me and I am happy with my experimental circuit but, let me tell you what the objectives have been for my own project.

Since AC motors are more efficient ( a well established fact) and do climb hills better, an AC motor is for me also. Anything that produces heat is a waste of energy unless you are trying to heat the car.

Batteries are heavy. Lead acid was out early in the project but I did try them. But also, too many LIPO4 cells can add too much weight and reduce both performance in terms of acceleration and even range can suffer if you go to extremes.

Weight in general is something to reduce as much as possible. I am an electronics tech and I have built aircraft with my father. Both have influenced me. If a car is built light but strong like an aircraft, it will perform well. Electronics can solve many problems and I have to do just that every day.

I had to determine the cost of everything and, the range that would work for me. I ended up with 63 miles before the BMS alarm goes off. I do this with a 140 Ah battery with a total of 72 LIFEPO4 cells.

But finally, I love to experiment and I will do just about everything differently. If not I could simply buy a electric car and be happy. It seems many of you have done the same in as much as you have converted your own cars. I will work hard and try anything and everything. I would even be willing to run a car on snake oil. If you are unwilling to try, to dream, to test, to do what they say can't be done, what is the point?

 

This "experiment" is a waste of time.

1. You are really the only expert when it comes to your own car. You build it to please yourself. In the end you will know every nut and bolt. My advice, don't try to impress others.

2. If you can't accept the first point, there is no point, and it is a waste of time to convert a car to electric.

3. I wish you well with your own project and I look forward to hearing more about it. I may not believe it thou.

 

Hi
I ended up with 63 miles before the BMS alarm goes off. I do this with a 140 Ah battery with a total of 72 LIFEPO4 cells.

So 72S = 230v? at 140Ah = 32Kwhrs - at 80% = 25.7Kwhrs
63 miles = 408 watthrs/mile

I hate to say this but that's not really impressive - my "Device" does 400 watt-hrs/mile and it is about as aerodynamic as a brick

Most cars do quite a bit better

If I drop the speed down to 50Kph then energy used goes to 200 watt-hours/mile

 

Hi
I ended up with 63 miles before the BMS alarm goes off. I do this with a 140 Ah battery with a total of 72 LIFEPO4 cells.

So 72S = 230v? at 140Ah = 32Kwhrs - at 80% = 25.7Kwhrs
63 miles = 408 watthrs/mile

I hate to say this but that's not really impressive - my "Device" does 400 watt-hrs/mile and it is about as aerodynamic as a brick

Most cars do quite a bit better

If I drop the speed down to 50Kph then energy used goes to 200 watt-hours/mile

I need to add some clarity here. There are two parallel banks of 36 cells. The peak voltage is not 230 volts. Absolute Peak is 120 to 124 volts at 140Ah. So that means less than 17Kwhrs. More like 16.8Kwhrs etc. This changes the picture quite a bit.

 

sirwattsalot,

I think the best thing for you to do is show a video to prove your claims, and for you to provide some real data a current and voltage probe might be a start.

you have also claimed that this circuit uses regen to and now you are saying that the car coasts and the battery recovers (as i thought you might)

what you have created is a work around for having batteries that suck. having impedances (read resistances) that do not match in your powertrain.

Or possibly a controller that is not tuned correctly?

this problem is usually solved by using a motor with a higher impedance or a battery with a lower one.

The capacitors that you have added are not working for the money or weight. If you want to make use of the capacitors they must be discharged to zero (or the reverse of the supply if they are AC caps) otherwise they are pretty much wasted. how much of the capacitor voltage that you have available is sitting idle? the supply voltage minus the difference between resting battery voltage and full sag. probably not a very high percentage.

I don't think what you have here doesn't work for you, there are better options, i mean you spent $600 on a capacitor bank you are hardly using, you could have got quite a lot more cells at the breakers with that.

You have really shot yourself in the foot with the way you have announced this, you could have gotten a much better reception.

 

sirwattsalot,

I don't think what you have here doesn't work for you, there are better options, i mean you spent $600 on a capacitor bank you are hardly using, you could have got quite a lot more cells at the breakers with that.

You have really shot yourself in the foot with the way you have announced this, you could have gotten a much better reception.

I appreciate your input. These are valid points worthy of careful thought and further investigation. This is the kind of feedback that I always hope for. Unfortunately, what has taken months to develop and test can be discredited in a few minuets. I simply report what I have done with my own car and the trolls come out. But, that is OK. I expect it. I even live for it. I get the very same at the car shows.

On the matter of more cells, I actually would like fewer. I am keeping the weight as low as possible and I am using stock suspension, brakes and tires. I have seen cars that were loaded with batteries and had no trunk space left over. Cost is a factor here. More battery weight means more expense to install hydraulic suspension etc. Someday, there will be better batteries with a much higher energy density. This will solve many problems and make my circuit totally unnecessary.

 

If you are running the AC 50, your controller can be set up to back the throttle off regardless of your accelerator input so that it never sags below a certain point. I have mine set up so that if any one cell goes down to 2.9 volts, the controller begins backing off, and then keeps backing off more and more to a point where no one cell can possibly go below 2.8 volts. If I climb a 6% grade on the freeway doing 80 mph, the voltage will start to sag, but then the car begins to slow down to whatever speed it takes to ensure that no cell drops all the way to 2.8. It is pretty smooth, and you can actually try to drive the pack into the ground by driving it until it stalls. The controller has a canbus, so you just hook that up to your Orion and get the BMS and controller talking. You can set it so that you can drive down a steep grade with a full charge and not overcharge the pack, you can set it up so that the pack never sags below a certain point, or so that no single cell ever sags below a certain point. All without having to feel any transition. Your AC 50 was a great choice.

 

I actually agree, He has said nothing that breaks any "rules"
It seems your a naysayer.

 

I found while driving my own EV that, if I hold the accelerator down too long, the motor draws a lot of current and the battery voltage sags low. The car simply will not go any faster under these conditions but, if I lift my lead foot off of the pedal for one second, the voltage lifts, the motor operates in regenerative mode and the car will again accelerate forward at peak performance for another 3.5 seconds when I put the pedal down again.

So you're essentially jerking the car up the hill... I agree with the others. Constant acceleration is better than the on-off modulation that you are applying.

Well OK but, who wants to constantly pump the pedal like that so, knowing this to be the case, I created a circuit that pulls back the accelerator by a percentage for one second every 3.5 seconds. I have the AC-50 motor, Curtis 3 phase controller with regenerative mode. This circuit is aided by a metal box of very large capacitors in the trunk space that can quickly absorb the charge during regenerative mode. The effects are subtle but, the driver can feel the bursts of acceleration each time the cycle completes. The car goes up hills better and generally performs better than before when the batteries are weak.

Regeneration? As in regenerative braking...slowing the car down then speeding back up. The equivalent of tapping the brakes then pressing the accelerator. Except instead of your losses being in friction of a pad and rotor, they are in the resistances of copper, iron, and semiconductors. Sure the capacitor can store energy, but that energy comes from braking the car...conservation of energy unless you have found lossless regen. Besides...you need a few thousand Farads to do anything useful in an EV for propulsion. Do you really think (or observe since you like experiments) that 3.5 seconds of full throttle discharge is equal to 1 sec of regeneration in your specific application? What everyone is getting to here is that you are wasting more energy pulsing the pedal instead of a smooth acceleration. Especially when the hill is trying to drag you back down...Physics

The effects are subtle but, the driver can feel the bursts of acceleration each time the cycle completes. The car goes up hills better and generally performs better than before when the batteries are weak.

We call that a butt dyno...throw the car on some rollers and see if you are gaining more power and for how long.

I have been able to get up to speed using no more than 200 amps which saves the batteries. 500 amps is the peak for the motor and controller. I was very glad to have this working on my last 63 mile test drive. I will share more of this experiment soon. I have not tried this in any other car or with any other motors or controllers.

Please do...I love numbers!

The secret to going farther is to not discharge the batteries too quickly.

Peukert's law

Many electric car manufactures are working on coasting technology which is somewhat different than what I am doing here. There are ways of reducing the discharge of the batteries or at least the big guys that build cars believe it. Coasting is exactly that. The vehicle freewheels down hills and by inertia at times during which there is no drain of energy from the batteries.

Yes, I'm working on one now. Many ways to skin this cat. You can't justify your experiment downhill as gravitational force is working with you, not against you as you are claiming above.

 

I want my car to go fast so I put my foot hard on the throttle the car didn't because of the voltage sag but if I slowly increase the throttle to limit the sag I go a lot faster.

If the caps are in the mix then isn't the batteries self recovering and the cap charging from the regen so when the throttle comes back on he will get the power from the caps and the batteries which would only reduce the sag untill the caps are flat then it would start all over again?

 

I want my car to go fast so I put my foot hard on the throttle the car didn't because of the voltage sag but if I slowly increase the throttle to limit the sag I go a lot faster.

That means you have a very poorly designed system and/or poor workmanship. If I had to guess you have undersized batteries which are not capable of delivering high current, undersize wiring compounding the problem, and poor connections further compounding the problem. Pumping the accelerator, any dang fool knows waist energy, not gain energy.

 

All you are doing is covering up a design flaw and/or poor workmanship fooling yourself into thinking it is a fix. I do not know what kind or size of batteries you have, but if you are demanding 1000 amps for any length of time means you need at least 200 AH batteries LFP batteries. Your are likely exceeding the battery capabilities. If they are properly sized to match the controller/motor demands, sufficient size wiring, with good connections, voltage sag should not be an issue.

So if you are seeing excessive voltage sag on the battery term plates, you have a battery problem, and no gizmo is going to fix it. You are barking up the wrong tree. Failure to address the real problem, over loading the batteries, is going to lead to premature failure of your batteries and extremely high fire risk.