2600MC Cooling

[Startrek (Martin)]

I haven’t used my 3 year old 2600MC for 5months since recently acquiring my new 2600MM.In an attempt to capture a comprehensive Dark Library, the 2600MC had difficulty cooling down to my normal -10C. It gets to -9.6 at 99% power and when you start taking short exposure darks (60 sec) the temperature starts going up progressively to -8.5 then -8.0 then settles around - 7.9 C. at 100% power. It’s obviously struggling
So I swapped cameras and set up the newish 2600MM and it cooled down very efficiently to -10.1C at 83% power and maintained that temperature whilst taking short darks.
Outside temperature was 22deg and humidity was 90%
I have no prior experience with these ZWO CMOS coolers so I’m guessing the 3 year old 2600MC cooler is functioning but running inefficiently.
When I last used my 2600MC back in May the outside temperature was quite cool heading towards Winter and it was operating fine at -10C.
It’s obviously struggling now as the cooler on the 2600MC is working but not efficient and is out of warranty so any replacement parts or servicing would be at time and cost.
I welcome any comments, advice or similar experiences with ZWO cooling.

Cheers
Martin

[glend (Glen)]

My experience with ZWO colour and mono versions of the 1600.

Any subs captured below 0C were pretty good. If your really concerned, grab the histogram for a sample of them and zoom in on the left side (where noise gives way to signal). I was using SGPro mostly for imaging software.
One trick for improving sub temperature stability, is to build in a cool down period between subs. This obviously extends session times but can over come weak cooler performance. One thing I tried, in summer, was piggy backing a laptop fan over the ZWO fan (as a boosted fan), that seemed to add -5C to the bottom end, depending on ambient temps at the time. It has been my view that ZWO doesn't design cooling for Australian summer evenings.

[Startrek (Martin)]

Thanks for replying Glen
Much appreciated
I got up this morning at 5am and did some more testing
The 2600MC cooled down to -10C @ 90% power consumption which was better than yesterday
Took 40 x 60 sec Darks and temperature dropped down to - 9.2C @ 98% power consumption and hung around - 9.0C to -9.2C for the whole duration
I am taking Darks inside the house which is warmer than outside by a few degrees ( ambient around 22deg ) however the humidity is ridiculous at 90 to 95%. Sydney has had 80% to 100% humidity for the past week.

A couple of observations and take always from testing -
According to ZWO the 2600MC has a designed working humidity range of 0% to 80% and a Delta T of 35.0C below ambient, so I am pushing the camera and cooler to its absolute limits and marginally beyond
As soon as the capture plan is completed the camera’s temperature drops back down to a nominal -10C within a minute.
Ive always taken a photo or two of the laptop screen at the start of each capture ( too lazy to look at logs ) and checked a few photos back in January/ February this year when temperature and humidity would be higher than the rest of the year. Camera was running at -8.8C to -9.1C with power consumption of 75 to 80% ( time was around 11pm )
This morning when I finished the capture and set the warming function , the camera warmed from -10C to +0.1C in less than a minute. ( normally it takes 3 to 5 minutes )
So I can only conclude that the 3.5 year old cameras cooling system is less efficient than when it was brand new ( my newish 2600MM proves that as the coolers are identical )
Humidity (more so than temperature) must play a huge roll in cooler performance as Sydney’s humidity is ridiculously high night and day this past week and will remain so until the weekend

Once the humidity drops to average or normal ( say 60% to 70% ) I’ll take some more Darks and see how the cameras cooler performs, hopefully a big improvement , fingers crossed.

Martin

[JA]

Originally Posted by Startrek

Thanks for replying Glen
Much appreciated
I got up this morning at 5am and did some more testing
The 2600MC cooled down to -10C @ 90% power consumption which was better than yesterday
Took 40 x 60 sec Darks and temperature dropped down to - 9.2C @ 98% power consumption and hung around - 9.0C to -9.2C for the whole duration
I am taking Darks inside the house which is warmer than outside by a few degrees ( ambient around 22deg ) however the humidity is ridiculous at 90 to 95%. Sydney has had 80% to 100% humidity for the past week.

A couple of observations and take always from testing -
According to ZWO the 2600MC has a designed working humidity range of 0% to 80% and a Delta T of 35.0C below ambient, so I am pushing the camera and cooler to its absolute limits and marginally beyond
As soon as the capture plan is completed the camera’s temperature drops back down to a nominal -10C within a minute.
Ive always taken a photo or two of the laptop screen at the start of each capture ( too lazy to look at logs ) and checked a few photos back in January/ February this year when temperature and humidity would be higher than the rest of the year. Camera was running at -8.8C to -9.1C with power consumption of 75 to 80% ( time was around 11pm )
This morning when I finished the capture and set the warming function , the camera warmed from -10C to +0.1C in less than a minute. ( normally it takes 3 to 5 minutes )
So I can only conclude that the 3.5 year old cameras cooling system is less efficient than when it was brand new ( my newish 2600MM proves that as the coolers are identical )
Humidity (more so than temperature) must play a huge roll in cooler performance as Sydney’s humidity is ridiculously high night and day this past week and will remain so until the weekend

Once the humidity drops to average or normal ( say 60% to 70% ) I’ll take some more Darks and see how the cameras cooler performs, hopefully a big improvement , fingers crossed.

Martin

Hi Martin,

yes l think that is the crux of it. Even in ZWO's own literature for the 2600mc and 2600mc they state:

" *The Delta T 35℃ is tested at 30℃ ambient temperature. It might get down when the cooling system is working for a long time. Also, as the ambient temperature falls, the Delta T would also decrease."

So from each of those statements I would conclude:

1. Its limits are a Delta T of 35 ºC at an ambient temperature of 30ºC, so -5
ºC camera temperature.
2. After some/long time cooling (?) the camera temperature may go down further.
3. Delta T of 35 ºC is the maximum temperature drop possible. At say 20 ºC ambient who knows what's possible, but given their comment, a -15 ºC camera temperature is unlikely. As to whether even -10 ºC is possible, it may be a little too close to the limit which is what you may be finding. Perhaps even manufacturing variation between the Peltier coolers or fans in the devices is enough to account for the differences between the 2600mc and 2600mm. It is hard to be certain.

One thing though operating at higher relative humidity, means the ambient air used for the cooling has a greater water content. This means that importantly that the air, in the context of heat transfer, will have a higher film heat transfer coefficient, since typical film heat transfer coefficients for liquids are 1 to 2 orders of magnitude times higher than those for gases. Now the humid air may only contain a few grams of water per kilogram of dry air, so it won't be as extreme as a 1 to 2 orders of magnitude, but it's enough to make it different.

A higher film heat transfer coefficient means the cooler has more difficulty in lowering the Aluminium fin temperature (for a given heat flux) whilst transferring heat across the air film boundary layer at the Aluminium / air interface where most of the heat is being exchanged. This results in a slightly higher aluminum fin temperature than with dry air and thus a slightly reduced ability in transferring heat from the sensor.

Best
JA

PS: I was going to suggest exactly as Glen did that the use of an auxiliary fan might get you to where you want to be. That also gives me another thought along the lines of your thoughts of your (possibly) aging 2600mc camera and that is, perhaps the fan maximum airflow varies or is different either due to aging or other factors. You could possibly test the differences (or not) between your two cameras with an airflow meter.

[Startrek (Martin)]

Originally Posted by JA

Hi Martin,

yes l think that is the crux of it. Even in ZWO's own literature for the 2600mc and 2600mc they state:

" *The Delta T 35℃ is tested at 30℃ ambient temperature. It might get down when the cooling system is working for a long time. Also, as the ambient temperature falls, the Delta T would also decrease."

So from each of those statements I would conclude:

1. Its limits are a Delta T of 35 ºC at an ambient temperature of 30ºC, so -5
ºC camera temperature.
2. After some/long time cooling (?) the camera temperature may go down further.
3. Delta T of 35 ºC is the maximum temperature drop possible. At say 20 ºC ambient who knows what's possible, but given their comment, a -15 ºC camera temperature is unlikely. As to whether even -10 ºC is possible, it may be a little too close to the limit which is what you may be finding. Perhaps even manufacturing variation between the Peltier coolers or fans in the devices is enough to account for the differences between the 2600mc and 2600mm. It is hard to be certain.

One thing though operating at higher relative humidity, means the ambient air used for the cooling has a greater water content. This means that importantly that the air, in the context of heat transfer, will have a higher film heat transfer coefficient, since typical film heat transfer coefficients for liquids are 1 to 2 orders of magnitude times higher than those for gases. Now the humid air may only contain a few grams of water per kilogram of dry air, so it won't be as extreme as a 1 to 2 orders of magnitude, but it's enough to make it different.

A higher film heat transfer coefficient means the cooler has more difficulty in lowering the Aluminium fin temperature (for a given heat flux) whilst transferring heat across the air film boundary layer at the Aluminium / air interface where most of the heat is being exchanged. This results in a slightly higher aluminum fin temperature than with dry air and thus a slightly reduced ability in transferring heat from the sensor.

Best
JA

PS: I was going to suggest exactly as Glen did that the use of an auxiliary fan might get you to where you want to be. That also gives me another thought along the lines of your thoughts of your (possibly) aging 2600mc camera and that is, perhaps the fan maximum airflow varies or is different either due to aging or other factors. You could possibly test the differences (or not) between your two cameras with an airflow meter.

Thanks JA
Excellent evaluation
I just need a day to test without this horrible humidity at the moment
Cheers
Martin

[Dave882 (David)]

FWIW- I can’t get my 2600mc to cool any more than 30degrees below ambient on hot humid summer nights. There has been several nights this last year that I had to change my setting from -10 to -5.
Also, it may be an ASIAIR control thing, but if my cooler maxes out to 100% then it stops cooling altogether (stays on 100% but temp rises to ambient). I lost several hours of data due to this silly glitch.

[Startrek (Martin)]

Originally Posted by Dave882

FWIW- I can’t get my 2600mc to cool any more than 25degrees below ambient on hot humid summer nights. There has been several nights this last year that I had to change my setting from -10 to -5.
Also, it may be an ASIAIR control thing, but if my cooler maxes out to 100% then it stops cooling altogether (stays on 100% but temp rises to ambient). I lost several hours of data due to this silly glitch.

Thanks Dave for your input
The main thing that caught my attention was the power consumption maxing out at 100%. My 2600MC has never done that since I bought it in July 2020.
During summer it’s always cooled close to -10C or at -10C but the power consumption was only 70 to 90% depending conditions, never 100% maxed out.
Again humidity in Sydney lately has been terrible so I’m waiting for lower humidity to run some more tests.
I’m sure it’s just age and conditions that’s causing this abnormality. The camera is working fine.
I’ve done all my imaging with both 2600MC and now 2600MM at -10C.

Cheers
Martin

[Camelopardalis (Dunk)]

Consider whether you really need to cool below zero.

For most exposure scenarios, the difference in the total dark noise is negligible once you get below 5C.

Just my 2c.

[Startrek (Martin)]

Originally Posted by Camelopardalis

Consider whether you really need to cool below zero.

For most exposure scenarios, the difference in the total dark noise is negligible once you get below 5C.

Just my 2c.

Hi Dunk,
A valid point
The 2600 series cameras have virtually zero dark current at -20C
Running at -10C is just taking advantage of the cameras wonderful performance, they’re not cheap cameras

Again I’m pretty sure that it’s the 90% + humidity in Sydney lately that’s causing the coolers suboptimal performance.
Friday we have a 22 deg day with southerly winds and 60 to 70% humidity
I’m confident that the cooler will maintain - 10C with 10 to 15% spare power
Cheers
Martin

[doppler (Rick)]

If there is dust on the cooling fan blades it will have a big impact on air flow and might be part of the problem?
Rick

[Camelopardalis (Dunk)]

Martin, I get it, the “getting your money’s worth”

But mathematically, it doesn’t stack up. The noise contribution from the temperature is already really small at 5C, to the point that in most scenarios it doesn’t significantly impact your total noise.

All I’m saying is, the great performance is from the sensor itself, and not just the cooler. The cooler is almost incidental, the noise levels are so good, but useful for keeping it consistent to make calibration viable. These sensors are such a step up from the previous generation (ASI1600 etc) and makes them look noisy by comparison.

Living in SE QLD, the summer nights are frequently “feels like” 30C or thereabouts, so what I use works well all year round, and I don’t have to mess around with different sets of darks

Anyhow, like I said, just my 2c…

[Startrek (Martin)]

Originally Posted by Camelopardalis

Martin, I get it, the “getting your money’s worth”

But mathematically, it doesn’t stack up. The noise contribution from the temperature is already really small at 5C, to the point that in most scenarios it doesn’t significantly impact your total noise.

All I’m saying is, the great performance is from the sensor itself, and not just the cooler. The cooler is almost incidental, the noise levels are so good, but useful for keeping it consistent to make calibration viable. These sensors are such a step up from the previous generation (ASI1600 etc) and makes them look noisy by comparison.

Living in SE QLD, the summer nights are frequently “feels like” 30C or thereabouts, so what I use works well all year round, and I don’t have to mess around with different sets of darks

Anyhow, like I said, just my 2c…

Thanks
Yep SE QLD has pretty hot, wet , sticky Summers
Maybe my slowly aging 2600MC is telling me to back off a bit and set me to -5C which is an easy fix.
Still I’ve had no issues in 3.5 years with -10C up until now
See how we go as I image from 2 vastly different locations
Cheers
Martin

[AstroViking (Steve)]

How is the ZWO cooler attached to the camera sensor? If it's like a computer's CPU, then any thermal paste / compound may have hardened and stopping the cooler from working properly.

It might also be worth opening the camera to verify that the air ways aren't plugged with dust / fluff, and that the fan is spinning freely.

Cheers,
V

[PaulSthcoast (Paul)]

Hi Martin.

I was going to suggest the same as Steve re the thermal paste.

I have had one of my zwo cameras begin to heat up rather thN cool down.

As it was out of warranty I opened it up and discovered the thermal paste had dried out.

A quick clean up and some new paste and away it went...good to go.

Just wondering if when your 2600mc had the 'oil leak' if the thermal paste was removed and or replaced ?

Easy to open it up and remedy if you are up for the investigation.

Paul.

[Startrek (Martin)]

Originally Posted by AstroViking

How is the ZWO cooler attached to the camera sensor? If it's like a computer's CPU, then any thermal paste / compound may have hardened and stopping the cooler from working properly.

It might also be worth opening the camera to verify that the air ways aren't plugged with dust / fluff, and that the fan is spinning freely.

Cheers,
V

Steve,
Thanks for your input
The cooler is working, but working hard at 100% power consumption to maintain the temperature to -10C ( the cooler is designed for a Delta T of 35C ie: Sydneys current temperature is 25C so that theoretically gives you 10 degrees below zero tolerance) Unfortunately the humidity in Sydney at the moment and for the past week is extreme 80 to 99% day and night , so I’m waiting until tomorrow to run more tests when the humidity will be down to 60 to 70%. The camera was serviced a while back when it had the thermal grease leakage ( along with hundreds of other ZWO 2600 cameras ) I have not had an issue since the service.
In regards to the cooling fan , you don’t need to open up the camera to clean it as there are 2 massive linear grills either side of the barrel housing which allows
you to reverse blast the internal chamber with compressed air or use a big hair dryer to clear the dust. I’ve already done that and the fan blades are clean and the fan spins at super high RPM with no bearing noise at all , just the sound of the blades cutting air.
You could very well be right about the thermal paste as my new 2600MM camera cools down to -10C with only 75 to 80% power consumption at the moment with all this humidity
By the way I am capturing a Dark Library inside the house ( camera sitting on a table in dark room connected to laptop with screw cap on ) so normally when imaging, the camera is in outside air in the scope which would have better thermal dissipation especially with a light breeze.
Whilst my 3.5 year old 2600MC is not cooling like it used to , I’m confident that when imaging outside with average humidity and temperature it will cool down to -10C and hang around that value hopefully all night.
I have the option to reduce cooling to -5C and still have super low dark current. These 2600 series cameras have ridiculously low dark current even at Zero degrees.

Cheers
Martin

[The_bluester (Paul)]

My 2600MC is about the same age and I have not had any issues with cooling it. I use -10 on both my cameras as that has proven to be something that they can maintain year round. In mid summer the cooler was working pretty hard to do it but it always did.

Have you checked that your power supply voltage is not sagging? That will reduce cooler performance.

[Startrek (Martin)]

Originally Posted by The_bluester

My 2600MC is about the same age and I have not had any issues with cooling it. I use -10 on both my cameras as that has proven to be something that they can maintain year round. In mid summer the cooler was working pretty hard to do it but it always did.

Have you checked that your power supply voltage is not sagging? That will reduce cooler performance.

Thanks Paul,
Yep power supply is good , voltage is nominal
Connections are good
New 2600MM at same temp -10C , same conditions only required a max of 80% power consumption to maintain -10C , whereas 2600MC requires 100% maxed out
Humidity is ridiculously high at 90 to 100% when running cameras ( inside the house which is even warmer than outside )
Just waiting for a cooler less humid day to run them

[Startrek (Martin)]

Finished off my Dark Library last night in the Study
Ambient temperature around 23degrees and humidity around 70% ( significantly lower than a few days before where is was +90%.
2600MC started cooling at a static camera temperature of 24C and cooled to -10C at 85% power consumption crept up to 89% but maintained -10C for over 3 hours.
So from the past week I can say that the 2600MC after 3.5 years of use has reduced its cooling efficiency to some degree but still cools to -10C except where conditions of humidity are extreme.
Down south at my Dome the humidity is no where near as high as Sydney so during the warmer months no issue down there.

Cheers
Martin