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Author Topic: Brushless motor constant running  (Read 2514 times)

Tone

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Brushless motor constant running
« on: August 02, 2010, 08:28:11 PM »

Any one have experience of constant running  a brushless motor
I am hoping to run a water cooled 35KV motor for the duration of 4 hours
varying the the voltage from 7.2v  up to 11.1 volts, depending on cells used

Thanks

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Prophet

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Re: Brushless motor constant running
« Reply #1 on: August 03, 2010, 09:57:18 AM »

what are you going to run the motor in for 4 hours?

To answer your question you can run the motor untill it burns out.. but even water cooled its going to get extreamly hot after about an hour. maybe you need to do more then water cool it .

with out information on what your running the motor in and what function the motor is going to preform ( prop drive / bow thrusters / water pump / etc) its hard to answer your question or give advice on what else to do in its place ...

what kinda battery are your going to use to give you 4 hours constant flow?? 24v car battery??

Send more info and we can send more/better advice

check this link ...
http://www.modelboatmayhem.co.uk/forum/index.php?topic=13206.0
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dodgy geezer

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Re: Brushless motor constant running
« Reply #2 on: August 03, 2010, 10:47:02 AM »

I would have thought that the motor on its own would reach thermal equilibrium quite rapidly - within 10 minutes or so. What may cause more problems is getting rid of the waste heat from the engine compartment, which will probably be a net heat absorber for 30 minutes or more, and then start heating up. Ventilation of the compartment will be a good idea even if the motor is water-cooled.

Given brushless speeds and power, I would also pay attention to bearing lubrication. If you're going to run a typical brushless motor for those lengths of time without bearing lubrication during running, I suspect you will see considerable bearing wear....
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Dekan

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Re: Brushless motor constant running
« Reply #3 on: February 12, 2011, 11:19:04 PM »

Most brushless motor have a fairly small shaft with low cost small bearings....I'm not sure how you would arrange them to be lubricated for 4Hrs

The ESC and the motor would need water cooling... So that means the motor would probably have to be an in runner..A problem if you want something low Kv

IMO brushless is not the first choice that comes to mind for the job  
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6705russell

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Re: Brushless motor constant running
« Reply #4 on: February 13, 2011, 09:35:34 AM »

Most brushless motor have a fairly small shaft with low cost small bearings....I'm not sure how you would arrange them to be lubricated for 4Hrs

The ESC and the motor would need water cooling... So that means the motor would probably have to be an in runner..A problem if you want something low Kv

IMO brushless is not the first choice that comes to mind for the job  

To achieve water cooling odes not mean the use of inrunners only, there are water cooled mounting brackets available for outrunners also..

Russ
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nick_75au

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Re: Brushless motor constant running
« Reply #5 on: February 13, 2011, 10:11:27 AM »

The thread as far as what the OP has asked is dead :P

There is no reason that a brush-less motor can not be run for 4 hours, if it is sized appropriately to the job, it will depend on the load the motor is put under as to what cooling requirements are needed, I haven't water-cooled any of my out-runner powered boats, the most they have is heat transfer from the front mount to the copper shaft tube, I should hope that the ball bearings would last more than 4 hours, brushless in theory need less cooling as compared to a brushed motor as  they are more efficient.

Nick
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Dekan

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Re: Brushless motor constant running
« Reply #6 on: February 14, 2011, 05:20:02 PM »

To achieve water cooling odes not mean the use of inrunners only, there are water cooled mounting brackets available for outrunners also..

Russ
Heat sinks don't conduct heat away as well as forced cooling...Just cooling a block of metal and attaching to an out runner is nowhere near as effective as water cooling an inrunner.....

Just ask the racing guys.....
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red181

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Re: Brushless motor constant running
« Reply #7 on: March 03, 2011, 11:38:28 PM »

I think Russ means something like this, not a water cooling plate as such, but a mount that is water cooled, brushless motors dissipate the heat at the front, so to cool the motor, especially an outrunner, the cooling is most efficient at the mount end of the motor.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=120692526035&ssPageName=STRK:MEWAX:IT

if set up correctly, a brushless motor will run indefinitely, something else like the shaft bearings will probably give up first, don't forget the esc can overheat also :-))
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