Heat ? How much ?

[jhnmflr]

Ok , I have a 2005 txt pds and just converted to 48 volts . Lifted , 22" tires and a dcx 500 amp controller , 2 gauge welding cable , solenoid and a stock motor . I know creeping with the sepex can be an issue . At what motor temperature should I be concerned ?

[Foot hill]

Not real sure. I just searched thus issue for same reasons.

Just returned from 5/6 hilly trail ride with wife,two year old daughter and me driving. @320lbs.
Stock Series motor
2ga cable
Hd. F/r switch
500 amp controller
On 36 volt

Took temp reading with ir gun and found motor case around 175deg.
(This is hard to keep hand on for more than two seconds)
Wandering also when damage would occur. Guess grease melting out of bearings would be first thing to happen.

[sportcoupe]

You never want to go past 200° F. in a golf cart electric motor. If you do it wont last long at all.

[JohnnieB]

It depends on the insulation rating of the windings in your motor.

Attached is a picture of the label on the Sepex motor in my 2008 PDS, stating it is Class H.
That means the absolute maximum operating temperature is 180°C (356°F)
However, that is winding temperature, not case temperature.
If your motor has less than a Class H rating , the max temp would be less.

The four commonly used NEMA insulation classes:
Class A = 105°C (221°F)
Class B = 130°C (266°F)
Class F = 155°C (311°F)
Class H = 180°C (356°F)

Case temperature is typically about 20°C (39°F) cooler than winding temperature and the peak temperature of the case lags behind the peak temperature of the windings, so the case temperature is not only lower, it reflects what the winding temperature was at a few moments earlier in time.

The highest case temperature readings will be in the vicinity of the bolts that attach the Field/Stator windings to the case, so that is where to attach a thermocouple or aim an IR thermometer.

I agree with sportcoupe that 200°F would be a goal to stay under for maximum motor life, but there isn't a magic number because everybody's cart is a bit different.

[NBeat]

I have a similar question about solenoid temp. Recently I've upgraded to 2 guage cables due to the fact the the originals were getting HOT and they are atleast 10 years old (only had this cart for a year). Since replacing the cables, I've noticed an improvement in torque and no more heat on the cables. Now that I'm heat sensitive, I noticed my stock series motor and solenoid are getting HOT. Earlier posts in this thread answered my motor temp questions, but what about the solenoid??? Does my solenoid have to much resistance, is it to old and needing replaced? I'm working my way toward 48volts, but need a HD F&R before upgrading the controller and solenoid from ScottyB. Do I need to take action to correct the solenoid temp or is this normal?

[Foot hill]

Originally Posted by NBeat

I have a similar question about solenoid temp. Recently I've upgraded to 2 guage cables due to the fact the the originals were getting HOT and they are atleast 10 years old (only had this cart for a year). Since replacing the cables, I've noticed an improvement in torque and no more heat on the cables. Now that I'm heat sensitive, I noticed my stock series motor and solenoid are getting HOT. Earlier posts in this thread answered my motor temp questions, but what about the solenoid??? Does my solenoid have to much resistance, is it to old and needing replaced? I'm working my way toward 48volts, but need a HD F&R before upgrading the controller and solenoid from ScottyB. Do I need to take action to correct the solenoid temp or is this normal?

Well, I think it's normal for the stock sol. To heat up under big loads. But remember most of the time we are not using our golf carts "normally"

So new hd for. Rev. Switch and controller with matching solenoid are needed to allow all current to go to your motor and not manifest into heating your stock parts.

Then... You'll be like me; wondering "how much heat is too much for stock motor?"

Never ends! Always something.
Enjoy.

[JohnnieB]

Ideally, the only thing that would heat up is the motor, but in the real world, there are no perfect conductors, contacts and connections, so everything has a finite amount of resistance and whenever amps flows through resistance, heat is developed.

Wherever there is heat being developed, there is power being lost that could be used by the motor to produce torque and/or RPMs.

The trick is to eliminate as much resistance as possible, or practical.

Here is a drawing of the high current circuit of a series motor. In addition the the Solenoid Contacts, Armature, F/R Switch, Stator, Controller, Battery Pack and Cables shown are the Motor Brushes and Interconnecting Cables within the battery pack.

Basically, all resistance it the single current path needs to be eliminated.

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When something with excessive resistance is eliminated, the item with the next greatest amount of resistance then becomes the hottest item, or the weakest link in the series chain.

IE: Replacing the cables that were getting hot, shifted the hot spot to the solenoid.
Replacing the Solenoid with shift the hot spot to the F/R switch.

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Since you are planning to go to 48V, go with a solenoid that will operate at both 36V and 48V, so you don't have to replace it when you up the voltage.