How to mesure run time with a KW/h rating.

[electrolux]

So, a battery is rated at: Nominal voltage: 393V Nominal energy: 23kWh.

A motor is rated at: 450Arms 325VDC (Can handle 393V) (I am presuming 'arms' means 'amps')

How do I measure the motors run time (Zero load) using the above battery? 

[SuzyC]

I donno what from watt, but what is a goceries man?

[PSR B1257]

450Arms 325VDC (Can handle 393V) (I am presuming 'arms' means 'amps')

No, it's A_RMS (https://en.wikipedia.org/wiki/Root_mean_square)

How do I measure the motors run time (Zero load) using the above battery?

Try a stopwatch 
Or an amperemeter and a bit math 


However, a 150kW motor and a battery with only 23kWh do not really match.

[electrolux]

450Arms 325VDC (Can handle 393V) (I am presuming 'arms' means 'amps')

No, it's A_RMS (https://en.wikipedia.org/wiki/Root_mean_square)

How do I measure the motors run time (Zero load) using the above battery?

Try a stopwatch 
Or an amperemeter and a bit math 


However, a 150kW motor and a battery with only 23kWh do not really match.

How did you know that the motor is 15kW?

[electrolux]

I donno what from watt, but what is a goceries man?

Is that a joke?

[PSR B1257]

How did you know that the motor is 15kW?

Not 15kW but 450A*325V=146250W close enough to 150kW (roughly estimated).

[Lightages]

So, a battery is rated at: Nominal voltage: 393V Nominal energy: 23kWh.

A motor is rated at: 450Arms 325VDC (Can handle 393V) (I am presuming 'arms' means 'amps')

How do I measure the motors run time (Zero load) using the above battery? 

That would be 450 Amps RMS. The only way to measure the run time with no load is to measure the actual current being drawn with no load and then do the math, or let it run until it stops or reaches the low voltage limit for the batteries and time it. The motor rating is at full load so the numbers given are useless to determine run time with no load.

[LukeW]

So, a battery is rated at: Nominal voltage: 393V Nominal energy: 23kWh.

A motor is rated at: 450Arms 325VDC (Can handle 393V) (I am presuming 'arms' means 'amps')

How do I measure the motors run time (Zero load) using the above battery? 

If you know how much energy a battery stores and you know how much power a load device draws then you can calculate how long you can flow energy out of the battery at that rate (power is the flow rate of energy, the time derivative) until all the stored energy is depleted.

Note that one unit of energy measurement is watt-hours... that makes it pretty easy. If energy flows into (or from) a battery at a rate of 1 watt for 1 hour then the total amount of energy transferred is 1 watt-hour.

[sunnyhighway]

I donno what from watt, but what is a goceries man?

I would categorize it as type-O.

[electrolux]

How did you know that the motor is 15kW?

Not 15kW but 450A*325V=146250W close enough to 150kW (roughly estimated).

Yes I meant 150kW, type-O.

[suicidaleggroll]

450Arms * 325V = 146.25kWrms

23kWh / 146.25kW = 0.157h = 9.4 minutes, assuming zero loss in your voltage conversion and wiring and zero ESR on the battery.  In reality it will be less than that, how much less depends on how significant those three sources of loss are.  That is assuming the battery doesn't overheat and explode with that much current draw.

[electrolux]

450Arms * 325V = 146.25kWrms

23kWh / 146.25kW = 0.157h = 9.4 minutes, assuming zero loss in your voltage conversion and wiring and zero ESR on the battery.  In reality it will be less than that, how much less depends on how significant those three sources of loss are.  That is assuming the battery doesn't overheat and explode with that much current draw.

Yeah I guessed it would be something like that. But I've found some cells rated at 400A 3.2V and the motor should run for around 35-40 Mins on that.

[Jeroen3]

Use the measurements on the motor drive display to determine run time.
Or are you just hooking up the battery to the motor?

[suicidaleggroll]

Yeah I guessed it would be something like that. But I've found some cells rated at 400A 3.2V and the motor should run for around 35-40 Mins on that.

A 400A rating is not the same thing as a 400Ah rating.  "400A" is a current rating, it means the cell can supply up to 400A without blowing up.  "400Ah" is a capacity rating, it means it can supply 1A for 400 hours before it's depleted.

If that was a typo and you meant 400Ah, then yes, you could stack 100 of those cells in series to get the voltage up, and then they could power the load for the greater part of an hour before they're depleted, provided they can supply 450A without blowing up.

[electrolux]

Yeah I guessed it would be something like that. But I've found some cells rated at 400A 3.2V and the motor should run for around 35-40 Mins on that.

A 400A rating is not the same thing as a 400Ah rating.  "400A" is a current rating, it means the cell can supply up to 400A without blowing up.  "400Ah" is a capacity rating, it means it can supply 1A for 400 hours before it's depleted.

If that was a typo and you meant 400Ah, then yes, you could stack 100 of those cells in series to get the voltage up, and then they could power the load for the greater part of an hour before they're depleted, provided they can supply 450A without blowing up.

It is a type-o. The cells are rated for up to 4K amp current draw. http://www.ev-power.eu/Winston-40Ah-200Ah/WB-LYP400AHA-LiFeYPO4-3-2V-400Ah.html

[onlooker]

The "9.4 minutes" mentioned was a full load estimate; while the OP was asking a zero-load estimate. My guess would be 10 or more times the 9.4 number. Then, to be sure, you need, as already mentioned by others, either measure the zero-load current or just time it . 

[tggzzz]

Yeah I guessed it would be something like that. But I've found some cells rated at 400A 3.2V and the motor should run for around 35-40 Mins on that.

A 400A rating is not the same thing as a 400Ah rating.  "400A" is a current rating, it means the cell can supply up to 400A without blowing up.  "400Ah" is a capacity rating, it means it can supply 1A for 400 hours before it's depleted.

If that was a typo and you meant 400Ah, then yes, you could stack 100 of those cells in series to get the voltage up, and then they could power the load for the greater part of an hour before they're depleted, provided they can supply 450A without blowing up.

It is a type-o. The cells are rated for up to 4K amp current draw. http://www.ev-power.eu/Winston-40Ah-200Ah/WB-LYP400AHA-LiFeYPO4-3-2V-400Ah.html

Those are very serious batteries that contain a lot of energy, ~4.5MJ. 1 ton of TNT contains 4.1GJ, so this this battery is equivalent to >1kg of TNT. Now you won't be able to get the energy out as fast as you can with TNT, but you will be able to get it out fast enough to do serious damage - particularly if the battery is shorted.

Consider that 450A*3.3V=1.5kW, and that domestic electric heating elements (fires, stove/hob rings) get red hot and they are only 1kW.

Be very careful that you have understood how your circuit and the battery will act when there are faults in either.

[electrolux]

Yeah, I'm not planning to do it just yet...