# Continuous Vs Peak power rating for a motor



## frk2 (Jan 2, 2009)

I have a ADC 6.7" 8hp motor rated at 6kw continuous and 16.5kw peak. At 72volts this translates to roughly 83amps continuous and 229amps peak. However when driving the amps MAY jump to around 250-275 if i accelerate really hard. Also i am almost always cruising at about 100amps

Is this going to damage the motor? Anybody else running the same 6.7" motor care to share their amps?

Also - how many times is it okay to touch that 'peak' rating? I live in a congested city and frequent stops and re-acceleration is required so I would say the amps go to about 150-180 every now and then - is this a problem?

Thanks!


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## Georgia Tech (Dec 5, 2008)

frk2 said:


> I have a ADC 6.7" 8hp motor rated at 6kw continuous and 16.5kw peak. At 72volts this translates to roughly 83amps continuous and 229amps peak. However when driving the amps MAY jump to around 250-275 if i accelerate really hard. Also i am almost always cruising at about 100amps
> 
> Is this going to damage the motor? Anybody else running the same 6.7" motor care to share their amps?
> 
> ...


whats the temperature of the motor? thats really going to be your dertermining factor...Also have you seen the brushes and com? If they are OK then you might be just fine...Which is what I suspect..


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## major (Apr 4, 2008)

frk2 said:


> I have a ADC 6.7" 8hp motor rated at 6kw continuous and 16.5kw peak. At 72volts this translates to roughly 83amps continuous and 229amps peak.


Hi frk2,

Where did those ratings come from? 

You raise some good points. The motor manufacturer can (and should) put out the continuous (or 1 hour (S2 in Europe)) rating. But the peak power of the motor is dependent on the supply. Rarely does a motor manufacturer specify peak power. And peak power does not relate directly to peak current. 

All this is this something I can't fully explain to you in a short post, or even a lengthy one.  But that size motor is what the KillaCycle runs. He uses a pair of them. But you think he sees a peak of 16kW? But then again you probably don't want to treat your motor like that.

I suspect you're o.k. But you should monitor the situation. Any thermal sensors in there? You check temps after a hard run? Inspected those brushes lately? At least you can see your current draw. And cruising at 100A on a 83A motor would indicate some concern. Got good ventilation for that sucker? Might want to force some more air thru it.

Regards,

major


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## frk2 (Jan 2, 2009)

Those ratings come from ADC. or correctly put from the vendor (cloudelectric). There are no temp sensors on that motor - I can maybe use a infra-red temp sensor to monitor the outside temperate but thats it. Ventiliation is good since the underside of the car is completely open and I suspect a lot of air gushes through there. 

The problem is that unless I drive my motor like that - my car is quite wimpy with those 12 x 6v batteries in there (totally 360kgs). Also - I drive in 3rd gear from the get-go - if I drive in second the acceleration is quite wimpy again - but the amps dont go that high. 

Is there a easy way to inspect the brushes?


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## major (Apr 4, 2008)

frk2 said:


> Is there a easy way to inspect the brushes?


You have to eyeball them. I don't know how many hours (or miles) you have on the motor. And you likely did not get a new brush length to compare against. But what would be signs of trouble would be excessive wear (short brushes compared to new length), uneven wear (some shorter than others), excessive accumulation of carbon dust in the motor, signs of arcing (burned or blackened components near the brushes and commutator) and uneven, burned or otherwise damaged comm segments (bars).

I think you can find pictures on the web of the good, bad and ugly WRT to brushes and comms. Key words like commutation, DC motor brushes, DC motor service, etc.

If your EV is relatively new on the road, take some simple measurements and pictures to compare against after a few hundred or thousand miles.

Here's what you don't want to see. http://hitorqueelectric.com/gallery/v/custom_motors/KillaCycle/DSCN1114.jpg.html 

A newer comm hardly "broke in". http://hitorqueelectric.com/gallery/v/custom_motors/warp9_101/ARMATURE+BANDING.jpg.html 

A well used comm but in o.k. condition. http://hitorqueelectric.com/gallery/v/custom_motors/Sepex+to+series/DSCN2435.jpg.html 

A brush showing signs of excessive heat at comm contact surface. http://hitorqueelectric.com/gallery/v/ouch/Stall+Marks/brush1.jpg.html 

Photos from http://hitorqueelectric.com/ I did not get permission to post them, but I don't think Jim will mind.

Regards,

major


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## gor (Nov 25, 2009)

technically - if motor comes w/o controller (to blame) - in case of failure, if hp or tq been exceeded - it'll be not covered by OEM warranty 

continuous and peak ratings:

PermMotors: PMS 120 

RatedPower 3,5 kW to 11,0 kW
PeakTorque 40 Nm
Pulse-Peak torque: only up to 30 % of rated rpm
Max. Peak torque at intermittent Duty: 1,5-times of rated torque for about 15 seconds
Max. pulse-torque: 2-times of rated torque for max. 0,5 seconds
-------------------

Agnimotors (front page): [FONT=AGMLLF+Tahoma]http://www.agnimotors.com/home
[/FONT]
Weight about11Kg. Up to9KW (12horsepower) at60volts, at only3000rpm, speed of about 50 rpm for each volt. 
The maximum continuous current varies from about 80 amps at12 volts to160 amps at 60 volts; *the limiting factor is the flow of cooling air through the motor and the continuous current at low voltages may be increased if ventilation is good**.* Maximum efficiency produced when running at about half the maximum continuous current. 

------------------------------

"MANTA"® #PMG226 PMG 
*10 HP MOTOR and/or **8000 WATT DC GENERATOR* 
http://www.hydrogenappliances.com/manta.html

Weight 22 lbs; 7.91" diameter / 5.64" length
Torque constant: 1.14 in-lb/Amp (0.13 Nm/Amp) 
12V to 48V *(has been run up to 96V / 45 sec. max. / 25 hp)* 
72 RPM per volt (3456 rpm @ 48V / continuous duty) 
10 horsepower continuous duty at 48 volts. 
*Max motor currents: 330A for 2 minutes / 480A for 45 seconds.* 
10 horsepower max at 48 volts continuous duty 
14 horsepower max at 60 volts continuous duty with optional air cooling port. 
*19 horsepower max at 72 volts for 2 minutes only! *
*28 horsepower max at 96 volts for 45 seconds only!*


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## frk2 (Jan 2, 2009)

So basicalyl I have to disassemble the motor to inspect the brushes. That is not a problem - will do whenever i have time. 

@gor - makes sense - I think the ratings just classify what the motor has been tested against. Anything over wont necessarily kill the motor but will definitely take the liability off the manufacturer.

Just out of curiosity - I showed my car to a few friends and they really gunned it while testing it out - afterwards there was that 'hot motor' smell from the hood. Is that okay?

How do i measure the core temperature on a motor thats sealed and has no built in temp sensor?


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## major (Apr 4, 2008)

frk2 said:


> So basicalyl I have to disassemble the motor to inspect the brushes.


No, I think that motor has a coverband. Just remove it and use a flashlight to look around. Just one screw


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## major (Apr 4, 2008)

frk2 said:


> How do i measure the core temperature on a motor thats sealed and has no built in temp sensor?


Install a thermal sensor either on a field coil or near a brush. Even on the outside of the frame for starters is better than nothing.


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## gor (Nov 25, 2009)

they say - fan on the rotor provides enough air flow for cooling oh high speed and rated load, but not enough on lover speeds and higher loads
where to put additional electric fan which would run depending on tempr. sensor? 
aluminum tube coils around the motor and small radiator like ICE oil cooler radiator ...
what the ways to deliver coolant (air or liquid) inside the motor - to the rotor itself?
pict: one of the ways, manta motors pmg226 : " For extreme racing applications you may wish 
to add a stream of compressed air at this point -> 2 [email protected] PSI for cooling rotor in extreme high amperage situations "
http://www.hydrogenappliances.com/manta.html
p.s. even if not compressed, but constant fresh air volume flow, independent of motor rpm, would do a good job (and better than nothing : )))


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## gor (Nov 25, 2009)

just a thought
hydraulic motors, pumps have their working medium - and the coolant -hydro fluid itself ... would be nice (and cool) to combine both (or at least to use some ideas, solutions to stay even cooler) : )))


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## gor (Nov 25, 2009)

gor said:


> they say - fan on the rotor provides enough air flow for cooling oh high speed and rated load, but not enough on lover speeds and higher loads
> where to put additional electric fan which would run depending on tempr. sensor?
> aluminum tube coils around the motor and small radiator like ICE oil cooler radiator ...
> what the ways to deliver coolant (air or liquid) inside the motor - to the rotor itself?
> ...


between air compressors - 200-300psi/low volume and regular fans - large vol./ little pressure, centrifugal air pumps might be ok 

Airhead 12V High-Output Air Pump $13.49
12V portable air pump puts out exceptional pressure and volume to inflate and deflate towables, boats, pools, mattresses and beach toys quickly
High-volume, pumps at 9.6 cu. ft./min., 8 psi 

Airhead 12 Volt High Pressure Air Pump 
New 12 Volt Hi pressure air pump w/pressure release valve produces 3 times the pressure of other 12 volt air pumps.
pump draws too many amps to plug into a cigarette lighter. Hook it up to your car, truck, or boat battery w/ the alligator clips on a 10' cord. Volume 410 liters/min. Draws 28 amps.

OUTCAST LVM 12-Volt Inflator
Weighs 1.5lbs (cables included) 
2.7 to 3lbs of pressure Air flow 21 to 29 cubic feet per minute


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