[gt40ev]

My project is getting closer and I've driven it around the block a few times but it's much too slow.

The car is a GT40 kit car built on a VW. It has 120 volts of 10 12volt used sealed lead acid batteries that used to be in a Ford think. Pack voltage checks out and my state of charge registers full power. The pack is seperated into 4 batteries in front, 2 behind the seats, and another pack of 4 in buried in the rear deck, all connected by 2/0 cable.

I have a Kelly KDH12400 (120v 400a) controller and a D&D ES-15A-6 motor coupled directly to the transaxle - no clutch. Shifting is no problem, but I just can't get up to to speed. At full throttle, the voltage from the controller won't go over 100 volts and the current ranges from 0-300 depending on the grade. The pack appears to drain slowly, but one or two will drain much faster and I have to charge them individually to keep the pack full.

I'm not looking to dust any Ferrari's, but I'd like to get up to freeway speed in less than 15 seconds while maintaining an average range of 40 miles per charge.

I'm already way over budget, but I need to fix the speed problem or the project is a failure. I'd rather not replace everything and if I can nail the problem down to batteries, controller, or motor then I can salvage my dream and my sanity.

I've gone over a few of the help pages on this site regarding motors, controllers, and batteries, and I'm thinking I should switch to LiFe batteries (I can fit a pack of 100ah thundersky's without modifying all of my racks) and/or consider going with a AC50 motor/controller setup, but that really means starting all over, which I would like to avoid if possible.

I'm a builder, not an engineer, so if you can keep it in layman's terms, then I'll have a much better chance of grasping what you're trying to tell me and put it into action.

Any ideas or suggestions on how I should proceed?

 

[major]

My project is getting closer and I've driven it around the block a few times but it's much too slow.

The car is a GT40 kit car built on a VW. It has 120 volts of 10 12volt used sealed lead acid batteries that used to be in a Ford think. Pack voltage checks out and my state of charge registers full power. The pack is seperated into 4 batteries in front, 2 behind the seats, and another pack of 4 in buried in the rear deck, all connected by 2/0 cable.

I have a Kelly KDH12400 (120v 400a) controller and a D&D ES-15A-6 motor coupled directly to the transaxle - no clutch. Shifting is no problem, but I just can't get up to to speed. At full throttle, the voltage from the controller won't go over 100 volts and the current ranges from 0-300 depending on the grade. The pack appears to drain slowly, but one or two will drain much faster and I have to charge them individually to keep the pack full.

I'm not looking to dust any Ferrari's, but I'd like to get up to freeway speed in less than 15 seconds while maintaining an average range of 40 miles per charge.

I'm already way over budget, but I need to fix the speed problem or the project is a failure. I'd rather not replace everything and if I can nail the problem down to batteries, controller, or motor then I can salvage my dream and my sanity.

I've gone over a few of the help pages on this site regarding motors, controllers, and batteries, and I'm thinking I should switch to LiFe batteries (I can fit a pack of 100ah thundersky's without modifying all of my racks) and/or consider going with a AC50 motor/controller setup, but that really means starting all over, which I would like to avoid if possible.

I'm a builder, not an engineer, so if you can keep it in layman's terms, then I'll have a much better chance of grasping what you're trying to tell me and put it into action.

Any ideas or suggestions on how I should proceed?

Hi gt,

1) Used batteries are always suspect. If you don't have both meters, battery voltage and battery amps, get them. Then record V and I during loaded conditions as best you can. For example, what is battery voltage at 100 amps, 200 amps, or 247 amps? Maybe have a passenger take some notes.

2) Kelly controllers???? People have had problems with them. A member named gottdi is a Kelly lover and swears the new ones are good. He hates it when I badmouth Kelly. I have no idea how to tell if the Kelly controller is a good one or a bad one. If it is the problem, Kelly may replace it for you. Once you verify the batteries are good, pursue the controller.

3) Motor sounds marginally small. D&D makes a good motor. Only the 6.7 inch diameter models. In a vehicle that size I think at least an 8" motor should have been used, probably with a 600 amp controller, if you wanted decent performance. That D&D should get you up to speed with a shifting transmission. Just that it may overheat.

I'd use the order which I listed. A bigger motor won't help a crappy controller. A good controller won't help crappy batteries. Lithium batteries would be a big help, but if your controller will never go above 300A, that will limit you to about 36 hp.

Regards,

major

 

[cruisin]

I would suggest that you do the following.
1) Upgrade the controller to at least a Kelly 800a
2) Upgrade the motor to a Impulse 9 (keep same bolt pattern)
3) If that is still not enough, goto Li-ion batteries.

I can help you with the motor and controller as I have some used in stock at [email protected]

I can also help you with Li-ion 18650 2.4a cells with tabs if like to solder and save some money.

 

[major]

I would suggest that you do the following.
1) Upgrade the controller to at least a Kelly 800a
2) Upgrade the motor to a Impulse 9 (keep same bolt pattern)
3) If that is still not enough, goto Li-ion batteries.

Hi cruisin,

Don't you think he should see if his present system is functioning properly before buying new components?

And gt40ev,

That Kelly controller has a computer connect port, right? Are you sure you have parameters configured correctly?

major

 

[GerhardRP]

I would suggest that you do the following.
1) Upgrade the controller to at least a Kelly 800a
2) Upgrade the motor to a Impulse 9 (keep same bolt pattern)
3) If that is still not enough, goto Li-ion batteries.

I can help you with the motor and controller as I have some used in stock at [email protected]

I can also help you with Li-ion 18650 2.4a cells with tabs if like to solder and save some money.

I agree with Major about diagnosis first, especially since you seem to be offering to sell this stuff, your advice is suspect.
Gerhard

 

[Jan]

It's always wise to listen to Major.

p.s. That car looks really fast. Now the rest.

 

[Qer]

It's always wise to listen to Major.

I second that!

 

[gt40ev]

Major, good stuff. Just what I was looking for. My voltmeter is currently wired to show how much voltage the controller is transferring to the motor but it's easy enough to move the negative lead to ground so it always shows pack voltage instead.

What exactly am I looking for? Or should I just post my results and see what the forum has to say about it?

I suspect it's the batteries. I have a battery tester that I got from Pepboys. It measures voltage at rest but also the condition of the battery underload. It's made for starter batteries but it tells the story. 8 of 10 tested great, one went to weak under load, and 1 showed almost dead under load. I'm going to charge those 2 seperately (it looks like my 120v charger isn't charging even?) before I run the tests.

With the pack full, I got the following results:

Mode Volts Current
no load, light throttle 129 50
no load, full throttle 121 60
light load, light throttle 129 75
light load, full throttle 125 100
heavy load, light throttle 120 200
heavy load, full throttle 110 350
full throttle from dead stop 115 400

All 10 batteries now read good (after charging the suspect 2).

What does this tell us?

Thanks
Tom

PS. with the 2 low batteries charged up, I got another 10 MPH

 

[major]

With the pack full, I got the following results:

Mode Volts Current
no load, light throttle 129 50
no load, full throttle 121 60
light load, light throttle 129 75
light load, full throttle 125 100
heavy load, light throttle 120 200
heavy load, full throttle 110 350
full throttle from dead stop 115 400

All 10 batteries now read good (after charging the suspect 2).

What does this tell us?

Thanks
Tom

PS. with the 2 low batteries charged up, I got another 10 MPH

Tom,

Tells us it works better with all the batteries charged But your V and I numbers are a bit mixed. Please confirm it is battery current, not motor current. Those are different.

And do you have access to the programming port? Can you see what the low voltage cutback is set at?

major

 

[gt40ev]

Major,

My shunt is between the contactor and the motor. Is that motor current or battery current?

The settings on the controller are:

Foot switch: disabled
Throttle effective start: 10%
Throttle effective end: 80%
max motor current: 100%
startup delay: .1 sec
control mode: speed
under voltage: 18v (the description for this reads "controller will cut back current at battery voltage lower than 1.1x the value, cut out at the value, and resume operation at 1.05x the value)
over voltage : 136v (I think this is for regen which I am not currently using)
throttle up/down rate: 15 (with fast being 1 and slow being 20)
power on high pedal disable: disabled
motor top speed: 100%
motor temp sensor: disable
controller stop output temp: 125C
controller resume temp: 110C

Do I have something set wrong?

If I'm measuring motor current and not battery current, how do I orient the shunt to measure what we're looking for?

Tom

 

[Bags]

Love the title for the thread.

Sure, diagnosis it first, and wring the most you can out of what you've got.

I'm a new EV owner, so take this with a grain of salt. When I try to accelerate on par with normal ICE cars, it takes 800A +/- 200A. At 156V nominal on lead-acid batteries, so sagging down to 145V or so when "full". When I've tried to hold the current under 400A, it accelerates so slowly that I feel people should be honking at me.

On flip side, though, I would love to get 40 miles per charge. I get much less than that. I'm not sure you'll be able to get 0-60 times less than 10 seconds and 40 mpc using 10 12V batteries. Unless you mount them on a motorcycle.

"YMMV"

 

[major]

My shunt is between the contactor and the motor. Is that motor current or battery current?

Hi Tom,

The Kelly wiring diagram shows the contactor in the battery positive line with a connection to the controller B+ terminal and then to the motor. If the shunt is between the contactor and B+ (controller terminal), then it is battery current. If the shunt is between the B+ (controller terminal) and motor, then it is motor current.

It would appear that the low voltage cutback (which you have set at 18V) is not entering into the mix. You would probably want to set that higher later on to actually protect your batteries, but leave it there for now.

That throttle up/down rate might enter into it. Now set at 15, maybe try 5.

Your tests show that the battery voltage is not tanking (dropping way low) on high current demand. And that you actually did see 400A, which I suspect, was motor current.

You say you did see another 10 mph after bringing back two of the batteries from a near death experience. I would continue to monitor the batteries. Usually, once a bad battery, always a bad battery. Although you might get it to stay up for a few miles per charge to gauge performance.

With you present system, 400A and 110V (under load), you'll never be over about 40-45 hp to the wheels and more likely 30-35. You should be able to select a gear to get you up in the 50 to 60 mph range, but will take a long time to accelerate up to that.

That's my take on it

major

 

[gt40ev]

Major,

I was talking to a couple of local guys and they both seem to think my batteries and controller should be fine, but that the 6.7 inch motor is my problem. They both seem to think that an 11 inch Kostov would have me shredding tires.

Would you agree?

 

[major]

Major,

I was talking to a couple of local guys and they both seem to think my batteries and controller should be fine, but that the 6.7 inch motor is my problem. They both seem to think that an 11 inch Kostov would have me shredding tires.

Would you agree?

The bigger motor will give you more torque for a given current. So at the 400 amp limit (on the controller) that additional torque may well be able to smoke tires. But you do have a 4 or 5 speed tranny, right? So, big deal.

The larger motor is not going to give you more power (maybe a little due to increased efficiency). The power is set by the controller (and battery voltage). The larger motor would allow you to run at high power for longer without overheating the motor. But, although you never stated your battery Ah, you may not have enough battery to run long enough to worry about that.

Now take that 11 inch motor and put an 800 or 1000 amp controller with it and a battery good enough to feed it, and yes, now you're talkin'

major

 

[Bags]

Now take that 11 inch motor and put an 800 or 1000 amp controller with it and a battery good enough to feed it, and yes, now you're talkin'
major

And I think that's the advice that everyone has been avoiding. Replacing these three components is essentially the "starting over" that you didn't want to do.

 

[cruisin]

My suggestion would be to get a AC-50 (your cost $4100) which will include a 500w Curtis controller. A added feature would be the programmable option of the controler unlike anyother. Re-gen is nice if you plan on doing city driving. Cant have it with a brushed DC. For info on the AC-50 email me at [email protected]

 

[Qer]

I was talking to a couple of local guys and they both seem to think my batteries and controller should be fine, but that the 6.7 inch motor is my problem. They both seem to think that an 11 inch Kostov would have me shredding tires.

I decided before not to get actively involved in this thread to not risk being accused badmouthing a competitor or just trying to sell you my own products, but to heck with that! I see that crusin has already passed that ethic line with a sonic boom, so whatever I say can't possibly be more questionable.

The motor is not your problem. The only things the motor can do is converting electrical power to mechanical power (+ heat, of course) or blow up trying. Replacing the motor will, as Major told you, not give you more power, only change the "gearing" between RPM and torque.

You have two weak components in your setup and that's the batteries and the controller. Your controller is only able to generate roughly 50 HP peak and given what I've heard and seen about Kellys I wouldn't be surprised if that drops to maybe 20 HP when the controller starts to heat up. That's pre-WWII Beetle performance...

Replacing the controller with something that can provide some real power (or even just with one that could provide you with 400 CONTINUOUS Amps..) will definitely make your car faster and funnier to drive, but even a serious high power controller can't give you high power if the pack's not able to provide it. Since you only see a sag to 110 Volt even at full throttle my guess is that the pack is in such a good shape that it's not that that is your real bottle neck here (even though a higher pack voltage probably wouldn't hurt...).

A better controller will definitely give you more torque at red lights and from what I can understand from this thread the pack is capable of providing more power than is used today so your top speed should also improve, but if you get a better controller there's always the question what will be the next bottle neck. If it's the batteries a good controller will let you add safe limitations to avoid damaging the pack and you'll at least have full pack power at your disposal. If it's the motor that's the next bottle neck life will be a bit more, err, interesting since a bigger controller could blow your motor...

One thing's for sure; replacing only the motor won't get you anywhere. At least not faster than today.

 

[Tesseract]

My shunt is between the contactor and the motor. Is that motor current or battery current?

The contactor should be between battery and controller. The shunt could be between contactor and controller (battery current) or the controller and the motor (motor current).

The settings on the controller are:

Foot switch: disabled
Throttle effective start: 10%
Throttle effective end: 80%
max motor current: 100%
startup delay: .1 sec
control mode: speed
under voltage: 18v (the description for this reads "controller will cut back current at battery voltage lower than 1.1x the value, cut out at the value, and resume operation at 1.05x the value)
over voltage : 136v (I think this is for regen which I am not currently using)
throttle up/down rate: 15 (with fast being 1 and slow being 20)
power on high pedal disable: disabled
motor top speed: 100%
motor temp sensor: disable
controller stop output temp: 125C
controller resume temp: 110C

I haven't seen a Kelly interface in a long time, but the setting I changed to red is wrong for an EV. You want to change it to, I believe, "torque" or "balanced". If you move the shunt over to the battery side I bet you'll never see it hit 400A. Keep in mind that the total power is delivered is determined by measuring the current and voltage on the same side of the controller, either battery or motor. So, battery current x battery voltage = total power... The maximum you can get from this controller, assuming the batteries don't sag (not realistic, of course) is 120 x 400 = 48kW, or ~64hp.

The Curtis AC controllers are really nice units, but the AC-50 combo might not feel any more powerful than what you already have.

The sag from your pack doesn't look too bad, so I'm guessing that you are measuring motor current - if you were pulling 400A from your lead-acid pack it would probably sag down to around 90V, rather than the 110 you saw.

That 6.7" motor is, in my opinion, a bit too small for an on-road vehicle. I didn't see how much your EV weighs, but if it's based on a VW chassis then it's probably fairly light so maybe change to an 8" NetGain or a 9" Kostov motor?

 

[EVfun]

The motor is not your problem. The only things the motor can do is converting electrical power to mechanical power (+ heat, of course) or blow up trying. Replacing the motor will, as Major told you, not give you more power, only change the "gearing" between RPM and torque.

You have two weak components in your setup and that's the batteries and the controller. Your controller is only able to generate roughly 50 HP peak and given what I've heard and seen about Kellys I wouldn't be surprised if that drops to maybe 20 HP when the controller starts to heat up. That's pre-WWII Beetle performance...

Replacing the controller with something that can provide some real power (or even just with one that could provide you with 400 CONTINUOUS Amps..) will definitely make your car faster and funnier to drive, but even a serious high power controller can't give you high power if the pack's not able to provide it. Since you only see a sag to 110 Volt even at full throttle my guess is that the pack is in such a good shape that it's not that that is your real bottle neck here (even though a higher pack voltage probably wouldn't hurt...).

One thing's for sure; replacing only the motor won't get you anywhere. At least not faster than today.

I want to agree (and disagree) with Qer.

The controller is your weakest link. You have enough controller for about 48-50 horsepower if it actually delivers a full 400 amps. I'm betting your VW kit car is heavier than my VW kit car (see avatar.) The thing is, my old Curtis 1221b has a reputation for putting out all 400 amps for long enough to actually make 50 HP (provided the vehicle is not to heavy, the continuous rating is only 150 amps.) That is enough to fake sporty performance in a 1400 lb. car and get to freeway speed in about 15 seconds. The Kelly has a reputation for barely hitting the peak amp levels when stone cold so you may be peaking out at something even lower.

The motor in your conversion is only 65 lb. and has a small 7/8 inch output shaft. I'm confident it will be the next weakest link. To go past 50-60 HP I would like to see at least a larger 6.7 inch motor (something around 90 lb. with a 1-1/8 inch shaft) or preferably an 8 inch Advanced DC motor (or the Netgain Impulse 9, a shorter but fatter motor that is nearly equivalent.) I wouldn't recommend a larger motor, one that makes more torque per amp, with your lower pack voltage. You will have more peak torque but you will move the rpm range of the power band down to the point of not matching the VW transaxle gearing well. My buggy is running a Prestolite MTC 7.2 inch motor and I can overheat the Curtis controller long before I overheat the motor.

You certainly don't need a controller that can put out 400 continuous amps unless you have a motor and batteries that can handle 400 continuous amps. That is at least 45 continuous horsepower. 400 amps will flatten an Optima battery in about 4 minutes. A motor with a 400 amp continuous rating will be about 300 lb.

 

[Qer]

I want to agree (and disagree) with Qer.

I'm cool with that.

So what would you say? A Curtis 1221 or 1231 instead of that Kelly would give a bit more acceptable performance in his car?