Custom (very) Quark esc heatsink... - RC-Monster Forums

Patrick · 04.05.2007, 09:47 PM

The loaded speed for a 7xl is 2145 I think, so 2145 x 16.5 = 35400rpm
The unloaded speed is 2382, so 2382 x 16.5 = 39300rpm

Hope this heatsink turns out well for you though. I've recently damged a second Quark with over heating problems. I use the heatsink from rc-monster, one 40mm fan, one 3'' fan and I don't think I was doing anything other the top with it setup wise, yet it still can't do a 5 minute race on 14 cells.

GriffinRU · 04.08.2007, 01:16 AM

Just to be clear on motor loaded - unloaded business.

If controller can handle it (high RPM) or limit it then there is no harm.
Mechanically Feigao motors rated at 50000 RPM Max (bearing and balancing wise).
Temperature more then 90Deg C is bad because of higher differential temp of magnet (mainly you should worry about magnet) and copper losses. Do not forget about balancing epoxy which can come loose and epoxy holding end-caps.

I am hearing a lot about loaded Kv numbers does anybody knows what the load is? Because there are lots of ways to calculate it and estimate.

With higher RPM current goes up because of inertia of rotor, so their will be RPM when it is less noticeable based on rotor size. And that is where power is dissipated and heat is coming from. And that is another reason not to run BL motors with out load or more correctly without control of RPM.

zeropointbug · 04.08.2007, 01:23 AM

Well, I did an eagletree test, and what I got was 42,000 rpm max, with a brief full throttle pull.

I can't remember the voltage the eagletree said, but either the volts the eagletree is reporting under load is wrong. OR, the rpm the eagletree is reporting is wrong. I am using the two wire RPM sensor.

Because that would require a voltage of 17.5 volts...... no way! The A123's under a little load will hover around 16 - 16.5 volts.

GriffinRU · 04.08.2007, 01:39 AM

Quote:

Originally Posted by zeropointbug

Well, I did an eagletree test, and what I got was 42,000 rpm max, with a brief full throttle pull.

I can't remember the voltage the eagletree said, but either the volts the eagletree is reporting under load is wrong. OR, the rpm the eagletree is reporting is wrong. I am using the two wire RPM sensor.

Because that would require a voltage of 17.5 volts...... no way! The A123's under a little load will hover around 16 - 16.5 volts.

Well, 2 phases to define RPM is not very accurate, but close enough. If you run this test many times then you can get better averaged value, couple runs is not enough.
5% error will be about 2100 RPM which is good resolution for given sensor pickup.

zeropointbug · 04.08.2007, 01:48 AM

I have been having voltage reading problems also with my eagletree lately.

It's been approx. 1 volt lower than it should be at max volts. Underload, I couldn't tell you , as there is no way of knowing, right?

zeropointbug · 01:54 AM

Also, I was looking at one of the fans that came off one of the GPU heatsinks. It;s small, very flat, and blows alot, ALOT for it's size.

I am just trying to figure out an efficient way of using it to cool my 7XL. I was thinking of using a shroud (don't know from where, or what :032: ) so it channels the air over the entire circumference of the motor heatsink.

It's a 12 volt fan, and uses 3.3watts, as confirmed with my power supply.

EDIT: I would take the rest of the frame off the fan to mount it.

Patrick · 04.08.2007, 02:54 AM

Quote:

Originally Posted by zeropointbug

I have been having voltage reading problems also with my eagletree lately.

It's been approx. 1 volt lower than it should be at max volts. Underload, I couldn't tell you , as there is no way of knowing, right?

Shouldn't it tell you what the voltage drops down to in the graph it gives you on the computer.

**Quark problems?? -** 04.08.2007, 05:40 PM

Quote:

Originally Posted by Patrick

The loaded speed for a 7xl is 2145 I think, so 2145 x 16.5 = 35400rpm
The unloaded speed is 2382, so 2382 x 16.5 = 39300rpm

Hope this heatsink turns out well for you though. I've recently damged a second Quark with over heating problems. I use the heatsink from rc-monster, one 40mm fan, one 3'' fan and I don't think I was doing anything other the top with it setup wise, yet it still can't do a 5 minute race on 14 cells.

Does this happen alot?? I was looking at a Quark and NEU motor combo but if it can't do 4S lipo's for more than 5 minutes I don't want to waste my money. will the Quark last the runtime of the batts in an E-maxx?