High torque motor getting hot will bigger controller help?

[KactusKiller]

Scotty, does a higher amp controller give more volts or did you mean "...a higher AMP controller should reduce heat..."?

[JohnnieB]

In general terms, sepex (and series) motors run cooler at 48V than they do at 36V.
Also, going from a 400A controller to a 500A controller is likely to increase motor heat rather than reduce it.

As for max motor temperature: When measuring at the motor case, keep it under 239°F. (Actual max for a motor with Class-H insulation is 356°F, but that is at the windings themselves, so it is derated when the winding temperature is being indirectly measured at the motor case.)

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It sounds like the field current might be too low when you are running at low motor RPM and with 23" tires your motor is only turning about 500 RPM at walking speeds.

What is the model number of your D&D motor?

Do you have a "Field Weakening Limitations Map" for it?

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I'm not all that familiar with a 1244 controller, but a quick glance at the manuals available on-line tells me it is a multi-mode controller with four switchable modes, so it could be programmed for low speed hunting with and without cargo, plus road speed with and without cargo.

The 23" tires will cause some heat issues, but I suspect proper programming will reduce it considerably.

What gear ratio is your differential?
If you have stock gears (12.44:1) going to 14.96:1 will almost offset the heat problems caused by the 23" tires.

[scottyb]

Amperage and voltage a two separate things.
Amperage, or current, is a measure of the amount of electrons moving in a circuit (to be used by the motor). A 500a amp control allows more current to flow.
Voltage is a measure of how much force those electrons are under. More force increases results.
Basically the work being done is a combination of amperage and voltage. When voltage is increased amperage is reduced for the same amount of work (watts) being done.
The working motor is consuming amperage but not at 100% efficiency. The amount of this amperage that is converted to heat will reduce if more voltage is applied. In this case I would definitely suggest 48v operation.

[KactusKiller]

It is a 48 vlt cart already

[JohnnieB]

Originally Posted by scottyb

Amperage and voltage a two separate things.
Amperage, or current, is a measure of the amount of electrons moving in a circuit (to be used by the motor). A 500a amp control allows more current to flow.
Voltage is a measure of how much force those electrons are under. More force increases results.
Basically the work being done is a combination of amperage and voltage. When voltage is increased amperage is reduced for the same amount of work (watts) being done.
The working motor is consuming amperage but not at 100% efficiency. The amount of this amperage that is converted to heat will reduce if more voltage is applied. In this case I would definitely suggest 48v operation.

Just a technical expansion on the highlighted comments.
The Ohm's Law formula for power that is usually seen is I x E = W. (Amps times Volts equals Watts)
However the Ohm's Law formula that tells the tale best is: I² x R = W. (Amps Squared times Ohms equals Watts ---- or Amps times Amps times Ohm equals Watts)

Basically, by increasing the pack voltage from 36V to 48V (a 33.3% increase) you reduce the amps by 33.3%, but reduce the heat by 66.7% (times the efficiency of the motor at the same RPM and under the same mechanical load)

In other words the relationship between Amps and Volts is linear while the relationship between Amps and heat is exponential.

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Since KactusKiller's cart is already at 48V, it is a moot point, unless he decides to up the pack voltage.

[sportcoupe]

Did D&D specify this motor for your cart with it's current mods? If so have you called Eric or Vic to explain what you're seeing heat wise? Be prepared to take exact temp as measured with an inferred temp gun or temp probe.

[KactusKiller]

Yes I have talked to Eric. I will try to acquire a thermostat and check temp.

[sportcoupe]

Harbor Freight has a couple cheap temp guns.

http://www.harborfreight.com/infrare...ter-93984.html

http://www.harborfreight.com/non-con...ing-60725.html

[scottyb]

So basically - this thread is just to ask us if Eric and Vic know what they are doing? LOL.
Usually when there is a mismatch, there is something in the load calculations they are not made aware of.

[Volt_Ampere]

A higher Amp output controller will get your motor Hotter. Heat loss in the motor is pretty much directly proportional to the current. (I times the Ra (resistance of Armature))