# DC Motor sucks amps and won't turn



## major (Apr 4, 2008)

Sparrow159 said:


> Is there some way a motor can suck the life out of the entire system like this but still test fine at 12V?


I don't think so.



> The motor is an 8 inch DC that's hooked up to a 156V 100 AH LiFEPO4 pack through a Kilovac controller that's able to go up to 180V.


I didn't know kilovac made a motor controller 



> .....and the voltmeter says error 1 or pretty much 0.


Your voltmeter gives you an error???? That's unusual. What voltmeter is it? How do you have it connected?



> I can hear some crackling noises from the motor. OK, I know what you're thinking - bad cable or battery. Here's the thing, I had run this same test previously with a different controller, batteries, potbox, quick disconnent, etc. The only constant is the motor and a few cables. I took the motor/adaptor out and tested with 12V. It ran fine. I reinstalled and still....the same result.


So this does not sound like a motor caused your problem.



> When I try to test the batteries under load I get 0. It doesn't matter if I start on the positive or negative side of the pack, once under load, everything goes to 0 - this shouldn't happen, I should get some voltage and be able to trace where the problem is.


Have you charged the battery? What are no load cell voltages? At what load and then what are the cell voltages? They all can't have an open circuit voltage and then all drop to "0" under load, unless your kilovac shorts out the entire pack. Even then, after the smoke clears, I'd expect a few millivolts. When was the last time you replaced the battery in the voltmeter? Are you using it correctly?

Your whole story is confusing. It might help me and others here to see any schematics, parts lists, photos of your installation, including the controller and voltmeter. 

Regards,

major


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## taken by aliens (May 26, 2011)

My guess is you have a loose ground or return. Check the cable connections again and make sure nothing is loose or disconnected.


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## GerhardRP (Nov 17, 2009)

So, is this you?
http://bigredbradley.blogspot.com/


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## Sparrow159 (Mar 30, 2010)

Major, 

Thanks for your help.The Kilovac controller is out of a Sparrow - 156V. I'm using a standard voltmeter, just to make sure it wasn't giving me bad readings, I used a second voltmeter and got the same result. The batteries were charged prior to the test and balanced using the MINIBMS. All batteries are sitting at 3.25V. The first test used a Curtis controller and gave the same result. That's when I swapped out the Curtis for the Kilovac. I have checked every 2/0 welding cable connection, everything is tight. Once I step on the accelerator, the entire system drops to zero. Yes, I know ---That shouldn't happen!


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## Sparrow159 (Mar 30, 2010)

Gerhard RP,

Yes, that's me. The picts show the Curtis controller. I have since then swapped it out for the Kilovac.


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## Nathan219 (May 18, 2010)

This may sound like a silly question, but is the parking prake on?


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## Nathan219 (May 18, 2010)

I think you know i ment brake.


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## GerhardRP (Nov 17, 2009)

Sparrow159 said:


> Once I step on the accelerator, the entire system drops to zero. Yes, I know ---That shouldn't happen!


Do you mean all voltages in the motor circuit are zero? That might mean that you are measuring relative to the frame. You should clip the negative lead to the battery pack negative terminal and measure everything from there.


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## major (Apr 4, 2008)

Sparrow159 said:


> Once I step on the accelerator, the entire system drops to zero.


Put the voltmeter across a single cell and see it read 3.25V. Have a friend step on the accelerator as you record the video of the voltmeter going to zero. Post that, please


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## peggus (Feb 18, 2008)

On your blog you say you used old silicone batteries:
"My first test was to put in some of my old silicone batteries and do a quick check to get the wheels moving. Things didn't go according to plan. When you press on the accelerator, the voltage drops to zero and only 30 amps were being sucked."

How old are these batteries and do you get the same result with the lithium batteries?


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## Sparrow159 (Mar 30, 2010)

It was the same result using both sets of batteries. Tonight I noticed that the back LED Stop/turn/tail light comes on when my wife steps on the accelerator.

At this point I thinking it's a 12V ground problem. I put the voltmeter across two of the buss bars I'm using to make the 12V ground wires easily accessible (starts at 0.00) and when the wife steps on the accelerator, it goes to the error 1 as well.


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## Sparrow159 (Mar 30, 2010)

Brake is off and the back end of the car is on jacks. Wheels turn, not easily because it's in gear.


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## DIYguy (Sep 18, 2008)

Sparrow159 said:


> It was the same result using both sets of batteries. Tonight I noticed that the back LED Stop/turn/tail light comes on when my wife steps on the accelerator.
> 
> At this point I thinking it's a 12V ground problem. I put the voltmeter across two of the buss bars I'm using to make the 12V ground wires easily accessible (starts at 0.00) and when the wife steps on the accelerator, it goes to the error 1 as well.


We need some more detailed information... like when the "whole system goes to zero"... what that really means.

I'm sure, as others have pointed out, that your battery voltage is not going to zero. Even a dead short, besides lighting something up, would show some level of voltage in the battery for some period of time.

I'm thinking that you are measuring at the wrong points also..as has been suggested. This "zero" you refer to, is it when measuring the 12 volt system???

One other thought here.... It would seem that you have a connection of some kind from your battery through your controller, to ground... downstream of the controller. If you do what Major suggests, you will learn something..like your battery voltage is not going to zero. If you have tail lights that illuminate when pressing the accelerator, you are putting power in this circuit somehow. I'm thinking that your voltmeter is not going to zero, but showing an error because it is "set to the wrong scale" for what it is seeing. Most DVM's have ranges or scales... and if you are trying to measure 12 volts but when your controller puts higher voltage into this 12 volt system, it goes in error because it is too high for the selected scale perhaps?? Perhaps the controller secondary is somehow connected to one of the 12 volt bus bars????

I would start by simplifying the test. Disconnect the motor from the controller and run it on 12 volts again...make sure it works ok. Then isolate the controller from everything except the minimum battery voltage...(like connecting one of your small packs) and a separate 12 volt source to it.(and to nothing else). Get your motor working with this scaled down set up, so you know the components are ok. Then when you start to connect the other things, do them one at a time while looking and thinking about each one.


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## Nathan219 (May 18, 2010)

Can you get the wheels spinning by hand and then try to run the motor? If the windings were wired out of sync wouldn't they act like a big inductor instead of opposing magnetic fields to spin the motor? A couple of pictures would let should confirm this. I haven't put in a DC system so I am only guessing. Lock one wheel from turning to make sure you are turning the motor, if the wheel is harder to turn or impossible with the accelerator signal present that would prove this theory.


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## Sparrow159 (Mar 30, 2010)

DIYguy,

My original post stated the result was an error 1. I assumed that was as good as a zero - alright...my bad!
I like your idea of using a different 12V battery to isolate the system. I'll need to reroute my contactor relay to the second 12V---I'll try that tonight. 

Thanks,


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## Sparrow159 (Mar 30, 2010)

I wired up a second 12V battery to isolate the EV 12V supply from the vehicle's 12V battery. I also relocated the grounds to an isolated spot on the chassis so it's not close to any other ground or buss bar that I am using. The only way the two batteries could cross is by the Blue Window; a 12V supply for the monitor is from the vehicle power and the video feed comes from the Blue window unit next to the shunt - that power comes from the EV supply. 

Sadly, the results were the same, the tires don't spin, limited amps - 30, and I smell some electrical burning after several seconds, I'm sure it's the motor. The tails lights still come on when the pedal is pressed down. The good news is I can now get a voltage reading from the batteries under draw, so I'll attack that process tonight after I make a long enough lead wire to go from the most negative battery post in the backseat to the front battery area.

Thanks for the ideas.


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## peggus (Feb 18, 2008)

Can you post a diagram of how you wired the motor? 
Is your shunt on the battery or motor side?


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## Sparrow159 (Mar 30, 2010)

The shunt is on the negative side, after the most negative post and before the controller. There is a 300 amp fuse attached there as well. The battery is wired according to the How to Convert book I have.

I pulled the motor again and it worked fine on a 12V battery then froze up. The hub/coupler had seized to the motor. I'm having 3/8 of an inch cut off the bottom of the hub/coupler to adjust. In addition, It looks like the flywheel might not be the right one. This is a 1967 swingaxle from a VW. I bought the car without the motor and acquired the flywheel elsewhere. Thus, I'm having the teeth ground off so there's nothing it can hang up on. 

Lesson learned: I probably should have tested the motor, adapter, transaxle all together first. Even though it is a [email protected]#$% to pull the transaxle.

Now for the million $ question - will I encounter the same electrical results once all this is done. I hope not.


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## EVfun (Mar 14, 2010)

Are you suggesting that the flywheel teeth are interfering with the bell housing of the VW transaxle? If so either you don't have a '67 transaxle or you don't have a VW Beetle flywheel. The Bug had 2 clutch sizes over the years, 180 mm and 200 mm. If you have an old 40 HP transaxle you need to clearance it to accept the flywheel for a 200mm clutch. Since this is an EV you can just remove the starter gear instead.


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## Sparrow159 (Mar 30, 2010)

EVFun, I took your advice and ground down the teeth on my flywheel. Then I thought I should check to make sure my clutch brake was sliding over the spline on the transaxle. Guess what? It didn't and won't. I'm not sure what they sent me but it ain't the right one. I ordered another one and got it in. Put everything back together and installed the motor. That's when I got a clunking noise when I stepped on the accelerator. Come to find out the Clutch pressure plate was grinding against an indentation in the transaxle bell housing. Looks like my adaptor assembly was off by about 1/4 inch. And all of this is after I ground down the flywheel and got a different clutch brake.

So there you have it, it wasn't an electrical problem at all. 

Thanks for everyone's help.


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