Black paint testing added
- Thread starter torqueon
- Start date
REdiculous
10 kW
Maybe the armature needs some vitamin C, so paint it orange instead. :lol:
Weird-Idea-Of-The-Week goes to torqueon!
Weird-Idea-Of-The-Week goes to torqueon!
TylerDurden
100 GW
Reid Welch said:
Reid Welch knew his shit.
Study up, kids.
fizzit
10 kW
Maybe not...
http://www.avweb.com/news/maint/182886-1.html
http://www.avweb.com/news/maint/182886-1.html
yopappamon
10 kW
I have heard that black attracts heat, but we aren't talking about racist cops, are we? :wink:
REdiculous
10 kW
What color is your car's radiator?...I think he just wants you to try handling hot spoons. :lol:
John in CR
100 TW
The fins on a radiator face each other, so increasing the emissivity of one fin only to radiate more heat just to be absorbed by its neighboring fin won't net any gain. The questions should be:
How hot does the armature get?
Where would the extra radiated heat go?
The paint would definitely not act as an insulator, because the rate of heat transfer to air is definitely less than the thermal conductivity of the paint.
FWIW, I painted my first hubmotor flat black from its original light grey with the intent of making it more emissive in an effort to try to get it to run cooler. I didn't notice any difference, which was probably due to the fairly low temperature and because now it can absorb more heat from direct sun.
How hot does the armature get?
Where would the extra radiated heat go?
The paint would definitely not act as an insulator, because the rate of heat transfer to air is definitely less than the thermal conductivity of the paint.
FWIW, I painted my first hubmotor flat black from its original light grey with the intent of making it more emissive in an effort to try to get it to run cooler. I didn't notice any difference, which was probably due to the fairly low temperature and because now it can absorb more heat from direct sun.
I am hoping to borrow a infared thermomonitor, to check unit after a run. The brush cage is open so I can aim it at the armature and than check the motor can to see the difference's
I suspect there's quite a difference. Because after a hard run, the motor can is warm, recheck after 5 minute's or so and it a lot warmer. The only place the heat can go is through the air gap and bearings
If the painting the armature works, more heat will go to the magnets and can.
I suspect there's quite a difference. Because after a hard run, the motor can is warm, recheck after 5 minute's or so and it a lot warmer. The only place the heat can go is through the air gap and bearings
If the painting the armature works, more heat will go to the magnets and can.
Ypedal
100 TW
I bet the differrence is negligable..
In direct sun, black will absorb more heat...
In shade, aparently, black will shed more heat but i dont see this being significant....
Paint it black for looks.. not for performance. :wink:
In direct sun, black will absorb more heat...
In shade, aparently, black will shed more heat but i dont see this being significant....
Paint it black for looks.. not for performance. :wink:
Kurt
10 kW
[/quote]What color is your car's radiator?...I think he just wants you to try handling hot spoons. :lol:[/quote]
I think most modern radiators and intercoolers are just a raw aluminium colour.
Kurt.
I think most modern radiators and intercoolers are just a raw aluminium colour.
Kurt.
Hillhater
100 TW
torqueon said:
Like you said... " no place for the heat to go"... so you have first got to move the heat out of the motor.
Get some air moving through there first.
Alan B
100 GW
Radiators don't do much cooling by radiating. So the radiative property of their coatings is not terribly important.
I expect if it were anodized black, it would work better than painted, as the paint will be likely a lot thicker than the anodizing.
Realistically, with the brushed powerchair motors I have, all of their outer casings are black, but they still retain most of their heat if operated under load with no airflow thru them. The heat has to get out of the coils and armature laminations, mostly by convection/radiation into the air inside the motor, and then from teh air into the magnets, and from the magnets to the thick steel housing, and then finally it can radiate/convect into the air. The only direct conduction it can have to the outside is via the thin motor shaft, into the bearings and casing (and gearbox).
Realistically, with the brushed powerchair motors I have, all of their outer casings are black, but they still retain most of their heat if operated under load with no airflow thru them. The heat has to get out of the coils and armature laminations, mostly by convection/radiation into the air inside the motor, and then from teh air into the magnets, and from the magnets to the thick steel housing, and then finally it can radiate/convect into the air. The only direct conduction it can have to the outside is via the thin motor shaft, into the bearings and casing (and gearbox).
John in CR
100 TW
Torqueon,
You don't want to send more heat to the magnets, because they typically can't handle anywhere near the temperature than the magnet wire can. If you have it open anyway, then some corrosion prevention couldn't hurt, and that would be in preparation for drawing outside air through the motor.
Unless you're already overloading the motor and overheating the rotor (smoke and smell come out when you stop), which you can only cure by a reduction in the gearing, then the real weakness of the motor is at the brushes and commutator. That's where brushed motors typically suffer failure. When you ventilate try to bring the fresh air in at that end.
I have one good quality high power brushed DC motor. It's a sealed motor and has big heat sink fins but only on the end cap close to the commutator and brushes. The finned end cap increased the manufacturer's power rating by 10% at 36V and also rated the motor for 48V use, another 33%.
Advice I feel compelled to give you though is, unless some budgetary concerns prevent a different direction, sell the brushed motor for whatever you can get for it unless you have some alternate use, and get yourself a BLDC motor. The reason is their only moving friction parts are the bearings. That means that other than a bearing change once a decade or so, they are good for life as long as they're not overloaded.
More specifically, I'd suggest the outrunner type, where the rotor containing the magnets is on ring outside of the stator that contains the windings. The reason for that suggestion is that they are more tolerant of power increases through increased voltage. That's because they are only hard limited by the rpm limits of the bearings and the physical strength of the steel ring holding the magnets.
Working to improve the performance of a brushed motor really is just polishing a turd, and your efforts to improve it are wasted. Many of us started the same route, including myself, and the time, money, and effort on brushed motors was wasted once we discovered BLDC motors.
You don't want to send more heat to the magnets, because they typically can't handle anywhere near the temperature than the magnet wire can. If you have it open anyway, then some corrosion prevention couldn't hurt, and that would be in preparation for drawing outside air through the motor.
Unless you're already overloading the motor and overheating the rotor (smoke and smell come out when you stop), which you can only cure by a reduction in the gearing, then the real weakness of the motor is at the brushes and commutator. That's where brushed motors typically suffer failure. When you ventilate try to bring the fresh air in at that end.
I have one good quality high power brushed DC motor. It's a sealed motor and has big heat sink fins but only on the end cap close to the commutator and brushes. The finned end cap increased the manufacturer's power rating by 10% at 36V and also rated the motor for 48V use, another 33%.
Advice I feel compelled to give you though is, unless some budgetary concerns prevent a different direction, sell the brushed motor for whatever you can get for it unless you have some alternate use, and get yourself a BLDC motor. The reason is their only moving friction parts are the bearings. That means that other than a bearing change once a decade or so, they are good for life as long as they're not overloaded.
More specifically, I'd suggest the outrunner type, where the rotor containing the magnets is on ring outside of the stator that contains the windings. The reason for that suggestion is that they are more tolerant of power increases through increased voltage. That's because they are only hard limited by the rpm limits of the bearings and the physical strength of the steel ring holding the magnets.
Working to improve the performance of a brushed motor really is just polishing a turd, and your efforts to improve it are wasted. Many of us started the same route, including myself, and the time, money, and effort on brushed motors was wasted once we discovered BLDC motors.
Alan B
100 GW
Just make sure you have a good easy failsafe emergency disconnect. The brushed controller failure mode to "go full blast" is pretty scary if there's much power available! BLDC doesn't have that problem!!
Picture's of some test I made. Temperature readings are left to right in the picture title
The black spoon 125f unpainted 94 f. The aluminium angle painted black on one side. the black side 40 f hotter than the unpainted side, Check the picture's i posted if there not there please let me know.
I did a motor test which consisted of a hard 2.5 mile run with 3 check points for the temperature of the motor can and armature
1st Motor can at 76f the armature at 112f
2nd Motor can at 85f the armature at 155f
3rd Motor can at 100f the armature at 210f
The motor resting for 10 min. the can and armature temps equalize
All this tells me is that black paint on the armature may help move heat to the can ! and Black on the can will move heat out to the world.
The next test is unpainted and painted armature in oven, heated until stable, remove and see which one cools off first.
The black spoon 125f unpainted 94 f. The aluminium angle painted black on one side. the black side 40 f hotter than the unpainted side, Check the picture's i posted if there not there please let me know.
I did a motor test which consisted of a hard 2.5 mile run with 3 check points for the temperature of the motor can and armature
1st Motor can at 76f the armature at 112f
2nd Motor can at 85f the armature at 155f
3rd Motor can at 100f the armature at 210f
The motor resting for 10 min. the can and armature temps equalize
All this tells me is that black paint on the armature may help move heat to the can ! and Black on the can will move heat out to the world.
The next test is unpainted and painted armature in oven, heated until stable, remove and see which one cools off first.
