# Please comment on wiring diagram...



## Rbertalotto (May 26, 2020)

Thank you in advance..

I'm new to this forum and wiring up a constant speed, 48v DC motor for a lawn tractor conversion.

This motor is designed for this application and does not use a controller. It runs at 3600RPM constant and tractor speed is controlled by tractor's transmission.

Can some one look at the attached wiring diagram to be sure I'm on the right track. 

The contactor is 400a / 48v

I have 400a fuses and holders. Do I need to fuse each battery? Or will one fuse at the last 12V battery feed suffice.

I'm using 2/0 copper welding cable with the longest run of 36"


Thank you for all your help.


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## kennybobby (Aug 10, 2012)

Was there any information about using freewheeling diodes on the contactor coils, or any snubber across the main contacts? also for the "switch" device shown connected to "ground"? Without something like this the life of the contactor will be shortened.

Is the chassis connected to the "ground" i.e. the (-) terminal of the lowest 12V battery going to the Motor (-)? That would be a good practice, but i wouldn't recommend to rely on the chassis to carry any return currents, use a wire with a fuse to provide a known good path.

Generally you need a fuse in a circuit to prevent wires from burning in case of a shorting event. If the chassis is grounded, then any wire that could rub against the chassis might short. 

The size of the fuse is determined by the size of the wire that must be protected. For all of the 2/0 gage wire then the 400A fuse might be okay, but for the little wire that engages the contactor coils, that is too big.


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## Rbertalotto (May 26, 2020)

Thank you...

Yes, I have the diode for the contactor. Sorry I didn't include it in the drawing.

The contactor gets its 48v from the mail battery in.....all it needs is a switched ground to activate.

So it appears all the battery interconnecting wires should be fused?


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## kennybobby (Aug 10, 2012)

no just one fuse per circuit--the main battery links are all in the same circuit, but the "switch" is a different circuit. 

Does the switch have a snubber or free wheeling diode too? You will need transient protection for both the contacts and the coil of the contactor 9for when you want to interrupt the current to turn them OFF)

Please redraw your schematic with the correct fuse and diode features.

You didn't answer about the grounding question.


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## Rbertalotto (May 26, 2020)

Here is how I was told by the manufacturer to wire the diode on the contactor


https://www.amazon.com/gp/product/B081DTWPN1/ref=ppx_yo_dt_b_asin_image_o00_s00?ie=UTF8&psc=1


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## kennybobby (Aug 10, 2012)

What kind of motor are you using, do you have a model or part number?

i couldn't find a real spec sheet for your contactor, but someplace indicated that the contacts were "silver oxide"--not sure if that is tarnished silver or some alloy?

but you do need the diode as shown, and a snubber (Resistor-Capacitor in series) across the main contacts (at least if you want it to last more than a few cycles of ON/OFF operation).

One big fuse to protect all the fat wires, and one small fuse to protect the wiring for the switch from the coil.


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## Rbertalotto (May 26, 2020)

Motenergy ME1004 Brush-Type Permanent Magnet DC Motor

This is the motor I'm using....


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## Rbertalotto (May 26, 2020)

> and a snubber (Resistor-Capacitor in series) across the main contacts


I'm surprised that the manufacturer of the motor never mentioned this when I spoke to them. Could it be built into the contactor.

If not, any idea of the value I'd need?


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## Rbertalotto (May 26, 2020)

Yup, need a snubber....The vendors web page spells it out pretty clearly. I sent them an email to ask what value I'd need. They offer a number of different values.,

https://www.evdrives.com/category_s/1926.htm


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## kennybobby (Aug 10, 2012)

Maybe they will give you some recommendations on the snubber values, if not we can calculatus some that will work for that thang.

Is this the sort of wiring scheme that you came up with after some research?
i'm using a single point ground at the pack low side, run wires for anything that needs to carry current, don't rely on chassis to be your current carrier except in off-nominal situations.


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## Rbertalotto (May 26, 2020)

Thank you very much...This is very helpful....I know enough about DC electricity to be dangerous. Learning more every day.....

So I looked at the little envelope that came with the contactor. It included the resistor....But no diode. I ordered the diode on their web page. 

The vendor that sold me the motor and contactor does not list capacitors on their web page. I emailed them to see what they suggest for values. Haven't heard back yet.

One fellow on another forum suggested I don't need a capacitor for a DC motor???? I have no idea if this is accurate.


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## Rbertalotto (May 26, 2020)

BTW...You show the 400A fuse on the negative leg.....Does it matter if it is on - or + ?


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## kennybobby (Aug 10, 2012)

Rbertalotto said:


> BTW...You show the 400A fuse on the negative leg.....Does it matter if it is on - or + ?


No it doesn't matter.


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## kennybobby (Aug 10, 2012)

Rbertalotto said:


> ...
> 
> The vendor that sold me the motor and contactor does not list capacitors on their web page. I emailed them to see what they suggest for values. Haven't heard back yet.
> 
> One fellow on another forum suggested I don't need a capacitor for a DC motor???? I have no idea if this is accurate.


Most folks with golf carts use the contactor to provide main power to their Motor Controller. They need the bypass resisitor to pre-charge the capacitors found within the motor controller box, then they use a throttle device to control the speed. They don't use snubbers across the contacts.

You said you don't need any speed control and are going to run it wide open with no controller. That is a very different situation than everyone else, and it requires a different solution. You don't need the precharge resistor, but you will want a snubber circuit to prevent damage to the precious metal contacts in the contactor when you switch it off. The snubber provides a conduction path for inductive spikes to dissipate in a similar manner that the diode does for the control coil. You could replace the snubber with a big ass diode also, but it would likely be a more expensive solution.

The fellow on the other forum hasn't really thought thru his suggestion; what do you think would happen if you wired it up with a resistor but no capacitor? What is the purpose of the resistor without a motor controller?


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## Rbertalotto (May 26, 2020)

> what do you think would happen if you wired it up with a resistor but no capacitor? What is the purpose of the resistor without a motor controller?



I have no idea...But before I wire this thing up I'm going to call and talk to a technician at the vendor


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## kennybobby (Aug 10, 2012)

Answer: If you put the bypass resistor, without a capacitor, then the motor will be energized thru the resistor all the time. It will be trying to run and bleed your battery down.

If you wire up the contactor without a snubber, then there will be arcing and sparking across the precious metal contacts whenever you turn off the motor. This will eventually pit, erode and frost over the surfaces such that it will no longer function. 

To see this you could use some car jumper cables to connect and run your motor directly from the pack, then notice the sparking when you make and break the connection, and the black residue on the tip of the clamp.


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## Rbertalotto (May 26, 2020)

Thank You for your help...Waiting to hear back from the vendor on the capacitor. 

Does the capacitor stop the bleed down of the battery?

If power is removed via the Deadman switch before the contactor, then I imagine I'll have no bleed down issues....??


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## kennybobby (Aug 10, 2012)

A capacitor will block DC but allow AC to pass.

What Deadman Switch? Do you have it on your diagram?


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## Rbertalotto (May 26, 2020)

No...I did not show the "Deadman" switch. It will be used to totally deactivate the tractor battery pack for security and in case of trouble. It will be wired between the positive of the battery pack and the contactor.

https://www.amazon.com/gp/product/B07T288VN8/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1


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## Rbertalotto (May 26, 2020)

UPDATED WIRING DIAGRAM...


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## Rbertalotto (May 26, 2020)

Well...I heard back from EV Drives, the supplier of the motor and contactor....

*Hi Roy,

No need for the Diode and Resistor. They are used when there is a solid state motor controller.

Regards

EV Drives

http://www.evdrives.com

1240 W Sims Way #1

Port Townsend WA 98368
Ph: 360-302-5226
Fax: 360-364-6004*


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## kennybobby (Aug 10, 2012)

Rbertalotto said:


> UPDATED WIRING DIAGRAM...


May need to add a Single-point Ground? From Battery (-) to Chassis.

May need to add a fuse on the 48V input to the converter? Or does it have one internally?

Maybe somebody else can join in to explain why you need the freewheeling diode on the coil. Without it you will have arcing in your ignition switch that will destroy it over time.

Same goes for an R-C snubber across the contacts.

If i am wrong and a snubber is not necessary, then you would be out a little bit of money for those parts. but if the other guys are wrong, then you will have to buy another contactor when this one fails.


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## Rbertalotto (May 26, 2020)

> May need to add a fuse on the 48V input to the converter?


.....YES, thanks for pointing this out.

I'm adding the resistor and the diode. It can't hurt and I agree with you on the inrush current being an issue. Not sure what the vendor is talking about.


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## kennybobby (Aug 10, 2012)

Don't put a resistor only across the contacts. That will be a short circuit that is trying to turn on your motor all the time. It doesn't do anything for precharge since you don't use a controller. You have nothing to precharge. 

Either use another diode (bigger and higher rating), or an R-C snubber, a resistor and capacitor in series together is a snubber.
https://en.wikipedia.org/wiki/Snubber


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## Rbertalotto (May 26, 2020)

How would I determine the values needed for the R-C Snubber?

And it would go across the two main contacts on the contactor?

Thank you in advance.....


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## kennybobby (Aug 10, 2012)

Determine the Inductance and current for your motor at the voltage you will run (probably on the motor datasheet or can be measured).

From this you can calculate the Energy stored in the inductance of the motor winding, 
as E(L) = 1/2 x L x I^2.

So the capacitor must be sized to handle and dissipate that energy,
E(C) = 1/2 x C x V^2.

Equate these and solve for C, this is a first order estimate of what is required.

Now the Resistor comes into play to reduce the current in the capacitor and dissipate the energy as heat, and it also affects the response time.

So does the motor freely spin down from 3600 rpm, or is there some sort of oil pump that it is connected to that will add drag to slow down the motor? We need some reasonable estimate of how quickly the motor will go from full speed to stopped. That time period will be used to determine the frequency associated with the response.

So you know the voltage is 48V, what current does the motor draw at 48V, and will the motor be running at 3600rpm or at some lower speed due to the load? The current will be higher as the load increases and drops the speed. 3600 is likely the no-load speed of the motor, but a datasheet with torque-speed curve would help answer that.

Here is a little simulation showing how the voltage spikes when the contactor (shown as a switch) opens. The motor is represented by the 500mH and 1.2 Ohm resistor. The values of the snubber can be adjusted to change the oscillation frequency and amplitude.


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## Rbertalotto (May 26, 2020)

Amazing on how helpful everyone is over here!

These are the only specs I can find on the motor

Power	6.4 KW continuous @ 48V
16 KW for 1 minute @48V
Voltage	24 - 48 Volts
Speed	3360 rpm at 48V Unloaded
Size 8" OD, 6.4" long (w/o shaft)
Shaft	1" x 3.1", 1/4" key shaft
Timed for counter-clockwise rotation (can be changed to clockwise)
Weight	30 lbs.

And this chart:
http://www.evdrives.com/v/images/Motors/Mars_Electric/ME1004_0025-CW.pdf

The only thing that might slow the motor down when stopping is slight friction on the disengaged pulley and V-Belt...Nearly nothing.

Description
The ME1004 is the same motor as the ME0708 but it has a double brush set to handle 200 amps continuous. This is a Permanent Magnet, Brush Type, DC Motor with Neodymium Iron Boron Magnets. The 1" shaft is similar to the shaft on most Lawn and Garden Tractor engines. This motor is perfect for an engine replacement on a Lawn and Garden tractor when converting the tractor to electric propulsion. No motor control is necessary for an engine-swap, but you will need to add a Contactor, Fuse, and 48 VDC batteries. For applications where a motor controller is required, we recommend that you use an SR-48500 and a solenoid that is rated for 400 amp continuous like the MZJ-400D with the appropriate diode & pre-charge resistor.Capable of 200 amps continuous, and 400 amps for 30 seconds. The efficiency is 90%.


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## kennybobby (Aug 10, 2012)

Take a look at this video from minute 20 to 22, to see the sparking in the contacts and how a snubber eliminates the spark. He does it in the reverse order for some reason. He shows the snubber he bought online somewhere in there too.

https://youtu.be/OAmXypXwkeg


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## kennybobby (Aug 10, 2012)

What is the load on the end of the pulley--what is it turning and how much torque does it take to turn? 
==========
Hydraulic Pump?
i assume it is a hydraulic pump of some kind. If so, then what is the power required for the pump, e.g. torque, speed and power for volume of fluid flow over what range of pressure? And what is the pulley ratio?
It may be that you need to parallel your pack to use 24V and double your current available; depends on how much torque you need to drive your load, and the pressure/flow rate needed.
===========

Not a Pump?
Just using the standard mower deck and transmission?
===========


Notice on the motor curve that it only draws ~10 Amps with no-load, but the current rises as the torque load increases and the speed drops.


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## Rbertalotto (May 26, 2020)

It is not Hydro transmission. It uses a Vario Pulley system. Push the lever forward and the pulley changes diameter to change ratio. Very simple. Like a snowmobile. In neutral the belt is simply slack.

I'll check out that video


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## Rbertalotto (May 26, 2020)

That was a great video! I learned a lot. Thank You.....

In watching it, I though of another question. To activate that contactor , I was planning on using the key ignition switch that the tractor already has. I have no idea what the specs are for it. 

Do you think this ignition switch can handle the 48v needed to activate the coil in the contactor, or should I use a relay to complete this circuit.

I have 12V "Ice Cube" relays and I have this Solid State Relay (SSR) from another project that I could use. I can get 12V DC from the DC to DC converter that the tractor will make available.










The SSR is 24-380v AC on the switch side. Would this matter in this situation?

Thanks


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## kennybobby (Aug 10, 2012)

*Re: Fotek DC-AC SSR*

It's a good idea but probably won't work. Here is a diagram from the datasheet found here, http://www.fotek.com.hk/solid/SSR-1.htm

They use optical isolation between the input and output, but the output is switched by a Triac fired by a circuit looking at the zero-voltage crossing of the AC output line; a DC ouput line won't have a zero crossing to initiate the firing. Notice they use a snubber circuit across the Triac switching element.


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## kennybobby (Aug 10, 2012)

*Re: Fotek DC-DC Solid State Relay*

Fotek does make a DC-to-DC SSR in a 5 and a 10 amp version for up to 60V.
http://www.fotek.com.hk/page1e.htm

The connection diagram shows they use a transistor for switching it ON, and also includes an internal snubber circuit.


And i found this good article about FAKE parts, with some links in the comments on building your own SSR,
https://www.instructables.com/id/The-inner-workings-of-Counterfeit-FOTEK-SSRs/


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## electro wrks (Mar 5, 2012)

I can tell you from experience most automotive type ignition switches will have trouble working above 24-32VDC. The arching-over problem is just too great. The switches rated for the higher DC voltages(key type or otherwise) are very difficult to find. The best solution, since you have added a DC to DC converter to your design, is to use a contactor with a 12VDC coil. This might mean you will have to have a small auxiliary 12V battery and/or some way to shut-off the main battery power to the DC to DC converter so it does not drain the main battery when the mower is shut down.

With the Vario Pully drive system (or any application where one motor powers both the drive and the mower deck), you'll want to retain the belt tightening or, if so equipped, the electric clutch system to dis-engage the mower deck so you can safely move around between mowing jobs. 

The no load, 3360RPM of the motor will be reduced to ~80%(~2690RPM) at full load. This might mean a change in pulley size to maintain a good mower blade RPM. You might find adding another 12V battery (if you use lead acid) or 3-4 more lithium cells in series to bring the voltage up, would bring the RPM up to a more useful range and give more power, if the motor can handle it. You might anticipate this with your DC to DC converter by getting one with a higher input voltage range capacity.


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## Rbertalotto (May 26, 2020)

thank you....i will use a relay, activated from, the key switch to energize the contactor.

i will not be running the mower deck off the tractors system. it will have its own 24v motors and its own batteries.....mounted on the front of the tractor for easier access to many areas of my property.

runnoing the mower deck off the tractors motor taxes the batteries too much....other have reported two or three hours run time for the tractor not mowing, but only 30 minutes with the mower deck in operation....


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## electro wrks (Mar 5, 2012)

I'm confused about what kind of mower you are converting. Do you have some model information or a photo of the mower or mower type?


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## Rbertalotto (May 26, 2020)

It is a Toro LX460 lawn tractor. I'll post pictures in a few minutes


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## Rbertalotto (May 26, 2020)




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## electro wrks (Mar 5, 2012)

Thank you for the photos.These Motenergy motors are primarily designed to power the mower deck, with the drive function as a much lower power secondary consideration-just like the original ICE. To use them for the drive only is a real overkill, power and expense wise. A much smaller motor(~1-3kW) really all that is need to move the mower around. This could be through the existing variable ratio pulley system, or better yet through a fixed ratio belt drive, with the ratio determined by trial and error. The small drive motor could be mounted close to the trans axle-freeing up more battery space in the front 

You would need a electronic controller for speed control. They are usually inexpensive in this size range and some have a convenient reversing function built-in. This might be a real plus because the manual reversing transaxle this type of mower has, from my experience, can be a real pain to shift a lot in tight back and forth mowing situations.

You wrote about a 48V battery powered drive system and a 24V battery powered mower deck. I'm still confused about the battery lay-out and how you intend to do this. Please explain.
Also do you have any shots of your mower deck?


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## Rbertalotto (May 26, 2020)

Thank you for the feedback....Much appreciated.

This is my first EV rodeo. I know this motor is much more than I need, but for the price difference to a less performance motor I decided to go this way. It will not live forever in this tractor. It will find its way into a much larger tractor, running hydraulics in the future. This tractor was given to me and has proven to be an extremely easy electric conversion. A great learning tool.

I thought about direct drive with a controller. Might go that way down the road. But the controller for this motor is $500.....I'm already into this project for nearly $2000.....Makes absolutely no financial sense...But then again, what hobby does!

I already have a wonderful ICE tractor that I reconditioned last month. You can read all about that here...www.rvbprecision.com

In answer to your questions, the tractor has 4, 12V , 110Ah AGM batteries. Two under the seat and two above the motor. This placement and weight will give the tractor excellent traction. Weight is a big plus in garden tractors. We fill the tires with liquid and hang lead weights on the wheels and front and rear brackets to increase weight and traction. This motor will be running through the existing transmission and belt system. The motor will be running 48v at full speed of 3300rpm. If this proves too fast, this motor can be run at 36 and/or 24 volts.

The mower deck will be front mounted with two 24v / 1500w motors turning two 19" blades. I will be building a LiFo battery for this application which will live on the front mounted mower deck. This should maximize my run time when mowing. The jury is still out as to whether these motors need to be 36V or even 48V. I'm still working out the math for blade tip speed vs torque required.

To say the least, I'm having a blast learning all this stuff!


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## Rbertalotto (May 26, 2020)

PS...I don't have a picture of the mower deck. Haven't built it yet. The tractor came with a three blade deck but I want a two blade which will be much more compact length wise. My yard is small and convoluted and a front mounted deck allows much more access to these "dead-end" areas of my property


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## electro wrks (Mar 5, 2012)

Well, obviously you have the skills, tools, resources, and gumption to do just about anything you want with this project! let us know how the variable ratio drive works in this application. My gut now says wheel spin and not much control; but it could be just bad gas.

I've taken apart and repaired the forward/reverse transaxle like the one in this mower. They are pretty light duty units. Not like the HD one in your Cub Cadet mower. Along with ~light duty frame, steering system, front spindles, etc. you might want to go with lightness and nimbleness, weight-wise, over heavy and hulking as you think about adding extra batteries and counterweights.

Anyway, continue having a blast, be safe, and keep us informed how it's going.


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## Rbertalotto (May 26, 2020)

Thanks..... And I still have that John Deere 214, a much heavier duty tractor waiting in the wings.....


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## Rbertalotto (May 26, 2020)

While waiting for my 2/0 wire to show up , I figured I'd do most of the 12v/secondary wiring and fabricate a few battery tie down straps. I also had a bit of #2 wire that I used for the less than 6" runs to the various components. I was concerned that I wouldn't be able to bend the 2/0 wire as needed. I'll have to keep an eye on them to see if they get too hot.


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## kennybobby (Aug 10, 2012)

Have you spun the motor with 12 volts just to run it in a bit for the brushes and determine polarity?


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## Rbertalotto (May 26, 2020)

Yes, I ran the motor on 12 v just to be sure it worked.


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## Rbertalotto (May 26, 2020)

Not sure what you mean..... determine polarity


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## kennybobby (Aug 10, 2012)

Make sure that it spins in the direction you want it to. Swap the polarity of the leads and it runs in the opposite direction.


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## Rbertalotto (May 26, 2020)

I found a spec sheet on the motor. Written in Chinese. But the "+" and "-" are clearly shown. It runs CCW like an ICE engine. My understanding is this motor can be run CW but needs internal modification. It is not a "reversible" motor.

I should be good to go.


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## brian_ (Feb 7, 2017)

Rbertalotto said:


> I found a spec sheet on the motor. Written in Chinese. But the "+" and "-" are clearly shown. It runs CCW like an ICE engine. My understanding is this motor can be run CW but needs internal modification. It is not a "reversible" motor.


I assume that we're still talking about the "Motenergy ME1004 Brush-Type Permanent Magnet DC Motor" listed earlier. Because it has a permanent magnet field, reversing the polarity of the input power does reverse the direction of rotation.

The only issue with reversing direction would be indicated by a line in the specs from an earlier post: "Timed for counter-clockwise rotation (can be changed to clockwise)". The brushes are slightly off of the neutral location for better performance at typical running speed. They would need to adjusted (that's the internal modification) to be similarly off of neutral in the other direction to suit the opposite direction of rotation. If the brushes were timed at the neutral position it would run just as happily in either direction by reversing polarity, but it would not be as effective.

Of course this doesn't matter, because the intended polarity is marked and the direction of rotation is known and matches this installation.

By the way, not all internal combustion engines rotate the same way, although counter-clockwise when viewing the end of the output shaft is the more common rotation, at least in cars.


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## Rbertalotto (May 26, 2020)

Here is a copy of my email to the motor vendor and his response:

_Thank you for a quick response.
But I'm confused. I can't find one EV "expert" that agrees that I don't need some type of inrush current protection on the contactor????? I'm told, worse case, I'll fuse the contacts in my contactor together or at least pit them badly.
Please help me to understand....._

_Hi Roy,
Without the use of a motor controller you will consume contractors over time with the large inrush of current every time the motor starts up._

Regards


I wonder how long "Over Time" would be......

ALSO...Another very helpful poster suggested I should use this capacitor across the contactor:

*Axial Capacitor 100 uF @ 450 VDC*

But he wasn't clear in what "across the contactor" meant......


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## kennybobby (Aug 10, 2012)

*Re: inrush limiting*

To limit inrush you could use an inductor coil (after the fuse and before the contactor). It would need to be rated to handle the maximum current, so wound with very low resistance using large gauge magnet wire.

It would help to know the inductance and resistance of the motor in order to know the electrical time constant and to match the impedance. Maybe the motor vendor or manufacturer would provide that info, or a datasheet with such specs?

The 100uF capacitor would be in the snubber circuit, the Resistor and Capacitor in series connected across the contacts as drawn in my diagram in post #10.


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## Rbertalotto (May 26, 2020)

IT RUNS!!!!!

I wired it up to run on 24V so it won't get away from me. Runs beautifully! Got something rubbing that is making that clicking noise. Need to fix that. I put it up against a solid fence post and it just sat there and spun the tires! Moter never got warm after riding for 17 minutes at 24V.

I only used the resistor across the two main power connections on the contactor. Will add a full snubber ASAP. 

Too much fun!

https://www.youtube.com/watch?v=OYEenfsjIj4&feature=youtu.be


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## electro wrks (Mar 5, 2012)

It lives! Sounds like a lot of gear noise from the transaxle. Usually, when I rebuild the non-hydrostaic(manual) TAs, I'll add a grease fitting to the housing and pump in extra grease. Sometimes 2-3 14oz tubes worth! Most manual TAs like this one don't have much in the way of seals to blow-out. The excess grease will leak out the input, output, and brake disc shafts. You'll want to remove excess grease that leaks out to keep it off the disc and input shaft V-belt.
This type of forward-reverse TA has a couple of large sliding bevel gears. Too much grease might keep them from easily sliding back and forth. So use caution when pumping in extra grease.


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## Rbertalotto (May 26, 2020)

The noise was the back of the belt rubbing on a locator pin. This new belt has the manufacturers logo stamped on the back of the belt and it rubs on a locator pin. I removed one of the pins but there is another under the motor that I'd have to take the whole tractor apart to get to it. If it doesn't wear in, I'll replace it with a ball bearing shaft.

Now the tractor only makes the noise when there is a bit of slack in the belt. When the belt is tight it is quiet.

Tomorrow I got to 48V and start popping wheelies!


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