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#### roach374

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I'm considering using this Curtis 1239e AC motor kit , and trying to figure out what kind of current I should expect this motor to draw at ~160V. This is for the purpose of getting the right connectors, fuses, wire gauge, etc for my setup (7x Tesla packs).

Should I just use the max current draw of the controller? (500A for 2 minutes, per the datasheet), or is there some other, more pessimistic number I should use? What's the right margin of safety for connectors, fuses, wire, etc?

#### John_G

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I am no expert, but that is not such an easy answer. Why? If you put that motor in a golf cart, it will likely never achieve 500A, even at 144v as there is not enough load; an unloaded motor draws only a few amps.

If the motor is rated for 144v and you apply 288 to it, the current will be MUCH higher than the rating under load.

If the motor is rated at 500A for 2 minutes, will it ever be operated at 500A for two minutes? Most commercial EVs are in the range of 300-400wHr/mile at highway speed as I recall. At 160v that would be just over 2A Leaf Wh/Mile, since Watts = V*A.

However, the motor controllers limit the applied voltage (volts = rpm), so if the motor needs 60v @ 60mph, that is more like 5A from the batteries. For example, if you have a 50kW motor and 160v batteries, the theoretical peak amps is 50000/160 = 312.5A.

#### roach374

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Thanks John_G. Still not sure I quite understand (even though I get that Watts = Volts * Amps, etc.). Could use some help with checking my math. My main concern is that I don't want anything to catch fire.

I'm planning on using the above motor kit, which includes the dual AC-50 motor, so two controllers. With 7 Tesla packs, that's about ~150V nominal. With two controllers, rated at 500A peak each, how do I determine what's an acceptable safety margin?

#### Frank

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Check with the vendor, #2 would probably work.

Sent from my SM-T380 using Tapatalk

#### Frank

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And at least 250VDC rating on fuses, etc.

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#### roach374

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And at least 250VDC rating on fuses, etc.
Thanks Frank. Any opinions on current draw?

#### John_G

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Thanks John_G. Still not sure I quite understand (even though I get that Watts = Volts * Amps, etc.). Could use some help with checking my math. My main concern is that I don't want anything to catch fire.
Remember, not an expert! But, rule #1 is the FUSE protects the WIRING from thermal damage not the devices.

I'm planning on using the above motor kit, which includes the dual AC-50 motor, so two controllers. With 7 Tesla packs, that's about ~150V nominal. With two controllers, rated at 500A peak each, how do I determine what's an acceptable safety margin?
That is a question for the supplier.

#### DansEVhobby

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I'm considering using this Curtis 1239e AC motor kit , and trying to figure out what kind of current I should expect this motor to draw at ~160V. This is for the purpose of getting the right connectors, fuses, wire gauge, etc for my setup (7x Tesla packs).

Should I just use the max current draw of the controller? (500A for 2 minutes, per the datasheet), or is there some other, more pessimistic number I should use? What's the right margin of safety for connectors, fuses, wire, etc?
what are you planning on doing to run accessories/lights in the car? Do you still need a dcdc converter for this system or is it handled by the pre charge resistors and relays?

#### roach374

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what are you planning on doing to run accessories/lights in the car? Do you still need a dcdc converter for this system or is it handled by the pre charge resistors and relays?
Good point! DC/DC converter, definitely, so I might need to account for high-current accessories (like vacuum pump and heater).

#### DansEVhobby

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Good point! DC/DC converter, definitely, so I might need to account for high-current accessories (like vacuum pump and heater).
I just heard back from Mike at EVpropulsion, and he said the reason he's having a hard time sourcing a dcdc converter to go with the 130V Hyper 9 controller he sells, is that for a dcdc converter to work it always must be in it's voltage range. So usually they go like 120-180...but if ur using something like that and ur battery pack goes under 120V of juice left, the converter and thus everything in the car would shut down.
So I guess that's the tricky part right now with the chip shortage n all, finding a dcdc converter with a wide range. He also said the Meanwell SD-500 he has used but it has a fan that continuously runs so it needs to be fiddled with and a contactor and pre charger added.

Pls let me know if you find a good dcdc converter for this project and I'll let you know if I find one too that's available currently.

#### John_G

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So this guy Damien tested various "AC" loads on DC and made a video about it, so I tried a few things I have about and yup

So, maybe a PSU from a server rack will work as they often have wide input voltages like a laptop PSU does

#### roach374

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... So usually they go like 120-180...but if ur using something like that and ur battery pack goes under 120V of juice left, the converter and thus everything in the car would shut down.
Ah, I think I misunderstood your question. I'm still planning to have a 12V battery in the loop (with the DC/DC to recharge it), which should give me enough juice to limp to a charger, if it comes to it. (though maybe not with the headlights, heater / high power accessories)

#### Sandra_Hart

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I'm considering using this Curtis 1239e AC motor kit , and trying to figure out what kind of current I should expect this motor to draw at ~160V. This is for the purpose of getting the right connectors, fuses, wire gauge, etc for my setup (7x Tesla packs).

Should I just use the max current draw of the controller? (500A for 2 minutes, per the datasheet), or is there some other, more pessimistic number I should use? What's the right margin of safety for connectors, fuses, wire, etc?
Oh, these calculations are too complicated for me to be honest. Although I have already started to learn math better, I am still self-taught and the process is slow... But, I can advise you Free solutions to polynomial graphs problems - PlainMath this service is a treasure trove of information in case you need to solve any math task or calculation. Whether it's algebra, geometry or calculus, you can deal with anything there. I hope you find the answer to your question and you will have streamlined calculations.
I think that I have to use some kind of tool, such as a calculator, to do such calculations, isn't it?

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