# ImPulse 8 Voltage\Current limits.



## kennybobby (Aug 10, 2012)

An unofficial rule of thumb says you may be able overdrive a motor for 5 seconds without damage at a power level 3 to 4 times the continuous power rating on the label. So find the motor specs and see what it says.

Of course you scare me somewhat when you say you have a 380 kW battery pack that doesn't sag...lol


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## Ziggythewiz (May 16, 2010)

Why use just one or the other instead of both all the time?


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## spaceballs3000 (Jun 22, 2012)

Ziggythewiz said:


> Why use just one or the other instead of both all the time?


From what I can tell of the performance charts ImPulse 8 at higher RPM/voltages it will not be as efficient as the AC motor at cruising speed.


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## spaceballs3000 (Jun 22, 2012)

kennybobby said:


> An unofficial rule of thumb says you may be able overdrive a motor for 5 seconds without damage at a power level 3 to 4 times the continuous power rating on the label. So find the motor specs and see what it says.
> 
> Of course you scare me somewhat when you say you have a 380 kW battery pack that doesn't sag...lol


So what is the label rating for the InPulse 8, I'm having hard time finding it. But for ImPulse 9 it list 72v at 90 ft/lbs, so I in could in theory dump in 288v for a few seconds giving 280 ft/lbs for that motor? btw I'm aware this would actually be much lower ft/lbs as to the additional loss due to increased voltages.

Well I shouldn't say no sag, as at >1000A at 380v, my cables will have significant drop.. so by the time it goes through the motor controller to the motor there will be significant losses.


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## nat_ster (Oct 19, 2012)

Interesting topic, looking forward to more discussion.

Nat


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## kennybobby (Aug 10, 2012)

*no it doesn't work that way*



spaceballs3000 said:


> So what is the label rating for the InPulse 8, I'm having hard time finding it. But for ImPulse 9 it list 72v at 90 ft/lbs, so I in could in theory dump in 288v for a few seconds giving 280 ft/lbs for that motor?


the continuous power rating is about 17 to 19 Hp at 190 amps. Short overload might be 60 to 80 Hp at 600 to 800 amps for 5 seconds, but the torque does fall off some due to saturation of the iron pole pieces.

Have you got a transmission /differential that can handle 280 fl/lbs? lol

What about all the extra rpms at 288v the motor wants to go 4x faster.
http://www.go-ev.com/PDFs/005_008_SU_NGT_FAQ.pdf


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## spaceballs3000 (Jun 22, 2012)

*Re: no it doesn't work that way*



kennybobby said:


> the continuous power rating is about 17 to 19 Hp at 190 amps. Short overload might be 60 to 80 Hp at 600 to 800 amps for 5 seconds, but the torque does fall off some due to saturation of the iron pole pieces.


This is useful information, and does make sense about the magnetic saturation of the iron pole pieces after x amount of power it put into the coils.



kennybobby said:


> Have you got a transmission /differential that can handle 280 fl/lbs? lol


At 280ft/lbs I'm near the limit of the differential, might end up rebuilding it after a few tests  or swapping it out with something better.



kennybobby said:


> What about all the extra rpms at 288v the motor wants to go 4x faster.
> http://www.go-ev.com/PDFs/005_008_SU_NGT_FAQ.pdf


Well I'll have full control of the single 1400amp (1200v) IGBT, so I can back off the power to the motor when I loose traction of either of rear wheels. 

The FAQ you link has some good info, i.e. 


FAQ said:


> Series wound motors, such as these, are renowned for the massive torque they produce from 0 RPM. These motors will suck every AMP they can in order to try and start the armature spinning. Though our motors are regularly abused by Zillacontrollers delivering 1000-2000 Amps for brief periods, the 9” motors are actually rated at 450 Amps for 5 minutes.


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## spaceballs3000 (Jun 22, 2012)

Opps I was wrong about my differential limit at 280ft/lbs, it's only ~70% of that, regardless I'll focus on this later if it become an issue.

back to the question at hand, since I'm doing short bursts, I'm going to assume the major limitation will be at the brushes where at high voltage will cause major arcing which causes a multiples of other issues. 

I called Netgain asking for answers about voltage over their max limit of 170v, and they said they will get back to me on my this unique application.


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## Frank (Dec 6, 2008)

In principle torque is more closely related to current and speed to voltage (for a given load.) Presumably that motor has the older brushgear and would be limited to 170V or so. Please post what Netgain has to say when you hear from them.


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