Separate power for mount - why?


ap@CaptivePhotons.com
 

First, I take all advice from AP seriously, and use a separate power supply for my mount now (AP1100AE). 

After my first attempt at night at a dark site, I need to redo my battery planning.  I ran dead before midnight with a Group 27 Lead Acid battery.  It was a bit premature due to a fallacy in the SOC indication I was using, but on further measurements I was way under sized and would have been completely dead before morning.  So a big 200ah LiFePO4 is on the way.

But that brings up the mount.  I have a Group 24 FLA for it, and that is more than adequate with its miniscule draw.  But it is about 50 pounds I lug around to the dark site.  I might replace it as well, say a 50ah LiFePO4, much lighter and smaller.  But expensive if not needed.

So here is the question: The recommendation is to have a separate DC power supply, due to noise from cameras, etc.

Is the recommendation based on trying to prevent damage to the CP4 or mount?

Or is the recommendation because it may create anomalies in tracking/guiding? 

Bottom line: Is there any reason not to give it a try off the same big battery, and so long as tracking is its usual near perfect self, not bother hauling (or buying) the separate battery?  If there's a risk of damage, obviously I'll keep two. 

I'm well aware in terms of investment the cost of another LiFePO4 battery is negligible, it is more about one more piece of "stuff" to haul out, back, etc.  The last trip I spent more time packing and unpacking than imaging.  Working to streamline other aspects also, but this one came up when I was debating whether to go ahead and order a second LiFePO4 battery or not.

Linwood


Roland Christen
 

There is no risk to damage to the CP controller. The main problem is undervoltage, so if you run many applications from one battery, the terminal voltage might drop below the threshold for the CP to operate properly. It is almost always an issue when slewing, not usually during tracking.

There can be one situation that happens during tracking when a dew heater comes on or cycles on-off. They can sometimes draw so much current from a 12 volt battery that the voltage at the terminals drops below 11 volts (about 10.5 to 10.7 volts) and causes the CP to reset. This results in a momentary stopping of tracking during the undervoltage time. Having a battery that puts out more than 12 volts, like the Lithium batteries, will prevent this situations.

We have also seen situations where the power supply was situated some distance away from the mount and the wire was too small to carry the current of all the devices without causing a fairly large voltage drop. So even though the terminal voltage at the power source was high enough, the actual voltage at the CP controller was down near the 11 volt threshold and even lower in one case that we saw.

Roland

-----Original Message-----
From: ap@... <ap@...>
To: main@ap-gto.groups.io
Sent: Mon, Jan 10, 2022 11:55 am
Subject: [ap-gto] Separate power for mount - why?

First, I take all advice from AP seriously, and use a separate power supply for my mount now (AP1100AE). 

After my first attempt at night at a dark site, I need to redo my battery planning.  I ran dead before midnight with a Group 27 Lead Acid battery.  It was a bit premature due to a fallacy in the SOC indication I was using, but on further measurements I was way under sized and would have been completely dead before morning.  So a big 200ah LiFePO4 is on the way.

But that brings up the mount.  I have a Group 24 FLA for it, and that is more than adequate with its miniscule draw.  But it is about 50 pounds I lug around to the dark site.  I might replace it as well, say a 50ah LiFePO4, much lighter and smaller.  But expensive if not needed.

So here is the question: The recommendation is to have a separate DC power supply, due to noise from cameras, etc.

Is the recommendation based on trying to prevent damage to the CP4 or mount?

Or is the recommendation because it may create anomalies in tracking/guiding? 

Bottom line: Is there any reason not to give it a try off the same big battery, and so long as tracking is its usual near perfect self, not bother hauling (or buying) the separate battery?  If there's a risk of damage, obviously I'll keep two. 

I'm well aware in terms of investment the cost of another LiFePO4 battery is negligible, it is more about one more piece of "stuff" to haul out, back, etc.  The last trip I spent more time packing and unpacking than imaging.  Working to streamline other aspects also, but this one came up when I was debating whether to go ahead and order a second LiFePO4 battery or not.

Linwood


--
Roland Christen
Astro-Physics


Woody Schlom
 

Linwood,

 

In my experience it’s the other way around from what you suggest.  It’s the MOUNT motors that dirty up the power – and the camera sees the “dirty” power as noise.  Something about mount motors (most, but not all) putting ripples in the power line.

 

Back when I was using live CCD video cameras, I could see the ripples in the power from the mounts.  And I could see that ripple disappear when I removed the mount from the same power source. 

 

But that said, I think there are ways of “filtering” power so this doesn’t happen.  All this is way above my knowledge levels, but in the past I was able to run all my equipment from the same power source without seeing ripple in the power.  I never singled out the “magic” configuration, but I think it had something to do with the type/s of power supplies.  I got the feeling that true old-school transformer power supplies (the ones that weigh a ton) were less susceptible to this than switching power supplies.  All I really know is that depending on the individual AC to DC power supplies I used in my configurations, every now and then I could power everything off the same power supply.  And other times I couldn’t.

 

But when I had the problem, giving the mount its own power supply stopped the ripple.  And when I stopped it, I mean I could look at my live video image and switch the mount’s power on and off – and watch the ripple come and go.  Mount ON, I had ripple.  Mount OFF, no ripple.  Simple as that.

 

Woody

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of ap@...
Sent: Monday, January 10, 2022 9:55 AM
To: main@ap-gto.groups.io
Subject: [ap-gto] Separate power for mount - why?

 

First, I take all advice from AP seriously, and use a separate power supply for my mount now (AP1100AE). 

After my first attempt at night at a dark site, I need to redo my battery planning.  I ran dead before midnight with a Group 27 Lead Acid battery.  It was a bit premature due to a fallacy in the SOC indication I was using, but on further measurements I was way under sized and would have been completely dead before morning.  So a big 200ah LiFePO4 is on the way.

But that brings up the mount.  I have a Group 24 FLA for it, and that is more than adequate with its miniscule draw.  But it is about 50 pounds I lug around to the dark site.  I might replace it as well, say a 50ah LiFePO4, much lighter and smaller.  But expensive if not needed.

So here is the question: The recommendation is to have a separate DC power supply, due to noise from cameras, etc.

Is the recommendation based on trying to prevent damage to the CP4 or mount?

Or is the recommendation because it may create anomalies in tracking/guiding? 

Bottom line: Is there any reason not to give it a try off the same big battery, and so long as tracking is its usual near perfect self, not bother hauling (or buying) the separate battery?  If there's a risk of damage, obviously I'll keep two. 

I'm well aware in terms of investment the cost of another LiFePO4 battery is negligible, it is more about one more piece of "stuff" to haul out, back, etc.  The last trip I spent more time packing and unpacking than imaging.  Working to streamline other aspects also, but this one came up when I was debating whether to go ahead and order a second LiFePO4 battery or not.

Linwood


Dale Ghent
 

My own experience with running everything off a single, common power source has not given me any issues that could be attributable to doing that. I get the feeling that there are two main reasons behind this advice, though:

One is that it's given with the aim of avoiding some (common? maybe at some point?) electrical issues with certain gear configurations - current leaks, noise, stuff like that. Stuff that's also hard to identify and quantify if you're not an EE or know what to look for. But this, I feel, is largely a situational thing and not something that affects every setup out there.

The other is around battery chemistries where there can be a large-enough voltage drop when the current draw suddenly increases - such as when a mount starts slewing. This voltage drop can be large enough to knock other equipment offline, cause them to reset, or even lockout into a safe mode. It's not great for gear and their own voltage regulation circuits. But, chemistries such as LFP don't tend to suffer from such precipitous voltage drops under load so you might be ok there if you're running everything off of a single LFP battery. These kinds of batteries didn't really exist, at least commercially, 10, 15 years ago.

On Jan 10, 2022, at 12:55, ap@... <ap@...> wrote:

First, I take all advice from AP seriously, and use a separate power supply for my mount now (AP1100AE).

After my first attempt at night at a dark site, I need to redo my battery planning. I ran dead before midnight with a Group 27 Lead Acid battery. It was a bit premature due to a fallacy in the SOC indication I was using, but on further measurements I was way under sized and would have been completely dead before morning. So a big 200ah LiFePO4 is on the way.

But that brings up the mount. I have a Group 24 FLA for it, and that is more than adequate with its miniscule draw. But it is about 50 pounds I lug around to the dark site. I might replace it as well, say a 50ah LiFePO4, much lighter and smaller. But expensive if not needed.

So here is the question: The recommendation is to have a separate DC power supply, due to noise from cameras, etc.

Is the recommendation based on trying to prevent damage to the CP4 or mount?


Or is the recommendation because it may create anomalies in tracking/guiding?

Bottom line: Is there any reason not to give it a try off the same big battery, and so long as tracking is its usual near perfect self, not bother hauling (or buying) the separate battery? If there's a risk of damage, obviously I'll keep two.

I'm well aware in terms of investment the cost of another LiFePO4 battery is negligible, it is more about one more piece of "stuff" to haul out, back, etc. The last trip I spent more time packing and unpacking than imaging. Working to streamline other aspects also, but this one came up when I was debating whether to go ahead and order a second LiFePO4 battery or not.

Linwood



Emilio J. Robau, P.E.
 

I am curious if my practices are best management practices.   I keep my cameras on one power source, my dew heaters on another, and my mount on the third.  I don't mix the power sources.  Is this overly paranoid?


Roland Christen
 

Switching power supplies have very little or no output capacitor filtering, so they are very susceptible to ripple. In fact, some have ripple even when no load is applied. Linear power supplies are heavier, but do have large output capacitors which essentially eliminate any ripple on the DC voltage.

Roland

-----Original Message-----
From: Woody Schlom <woody_is@...>
To: main@ap-gto.groups.io
Sent: Mon, Jan 10, 2022 12:18 pm
Subject: Re: [ap-gto] Separate power for mount - why?

Linwood,
 
In my experience it’s the other way around from what you suggest.  It’s the MOUNT motors that dirty up the power – and the camera sees the “dirty” power as noise.  Something about mount motors (most, but not all) putting ripples in the power line.
 
Back when I was using live CCD video cameras, I could see the ripples in the power from the mounts.  And I could see that ripple disappear when I removed the mount from the same power source. 
 
But that said, I think there are ways of “filtering” power so this doesn’t happen.  All this is way above my knowledge levels, but in the past I was able to run all my equipment from the same power source without seeing ripple in the power.  I never singled out the “magic” configuration, but I think it had something to do with the type/s of power supplies.  I got the feeling that true old-school transformer power supplies (the ones that weigh a ton) were less susceptible to this than switching power supplies.  All I really know is that depending on the individual AC to DC power supplies I used in my configurations, every now and then I could power everything off the same power supply.  And other times I couldn’t.
 
But when I had the problem, giving the mount its own power supply stopped the ripple.  And when I stopped it, I mean I could look at my live video image and switch the mount’s power on and off – and watch the ripple come and go.  Mount ON, I had ripple.  Mount OFF, no ripple.  Simple as that.
 
Woody
 
From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of ap@...
Sent: Monday, January 10, 2022 9:55 AM
To: main@ap-gto.groups.io
Subject: [ap-gto] Separate power for mount - why?
 
First, I take all advice from AP seriously, and use a separate power supply for my mount now (AP1100AE). 

After my first attempt at night at a dark site, I need to redo my battery planning.  I ran dead before midnight with a Group 27 Lead Acid battery.  It was a bit premature due to a fallacy in the SOC indication I was using, but on further measurements I was way under sized and would have been completely dead before morning.  So a big 200ah LiFePO4 is on the way.

But that brings up the mount.  I have a Group 24 FLA for it, and that is more than adequate with its miniscule draw.  But it is about 50 pounds I lug around to the dark site.  I might replace it as well, say a 50ah LiFePO4, much lighter and smaller.  But expensive if not needed.

So here is the question: The recommendation is to have a separate DC power supply, due to noise from cameras, etc.

Is the recommendation based on trying to prevent damage to the CP4 or mount?
Or is the recommendation because it may create anomalies in tracking/guiding? 

Bottom line: Is there any reason not to give it a try off the same big battery, and so long as tracking is its usual near perfect self, not bother hauling (or buying) the separate battery?  If there's a risk of damage, obviously I'll keep two. 

I'm well aware in terms of investment the cost of another LiFePO4 battery is negligible, it is more about one more piece of "stuff" to haul out, back, etc.  The last trip I spent more time packing and unpacking than imaging.  Working to streamline other aspects also, but this one came up when I was debating whether to go ahead and order a second LiFePO4 battery or not.

Linwood

--
Roland Christen
Astro-Physics


Woody Schlom
 

Emilio,

 

“overly paranoid?”  Maybe, but your approach should also work very well and give the fewest problems.  Personally, if you can do what you’re doing (three separate power sources), I’d keep doing it.

 

Woody

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Emilio J. Robau, P.E.
Sent: Monday, January 10, 2022 10:24 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Separate power for mount - why?

 

I am curious if my practices are best management practices.   I keep my cameras on one power source, my dew heaters on another, and my mount on the third.  I don't mix the power sources.  Is this overly paranoid?


ap@CaptivePhotons.com
 

On Mon, Jan 10, 2022 at 01:15 PM, Roland Christen wrote:
There is no risk to damage to the CP controller. The main problem is undervoltage, so if you run many applications from one battery, the terminal voltage might drop below the threshold for the CP to operate properly. It is almost always an issue when slewing, not usually during tracking.
Thank you, that makes perfect sense.  In this case, at a dark site, I'll have the battery right beside the mount, heavy gauge wire, and at 200ah (and LiFePO4 chemistry) there's going to be no unexpected drops unless I somehow run it dead also.  

To your later comment on switching power supplies, I take it that's one reason you recommend a dedicated power supply.  But those things are light, and it's all on one cart, there's no reason not to keep those separate. 

Saving me hauling an extra battery is a goodness.  Thank you for the quick response.

On Mon, Jan 10, 2022 at 01:24 PM, Emilio J. Robau, P.E. wrote:
I am curious if my practices are best management practices.   I keep my cameras on one power source, my dew heaters on another, and my mount on the third.  I don't mix the power sources.  Is this overly paranoid?
My difficulty with that is I use a Pegasus powerbox on the saddle as a dew controller, and also as a USB3 hub. While I have not experienced problems, it does worry me that a lot of noisy things come together there.  Running separate power to the dew heaters means a separate dew controller (or just running them 100%), and I still have the camera (and guide camera) and hub all together.

I just generally hope I can SEE the problem if one develops, e.g. as banding or something in images, and indeed I did in a case where the NUC noise affected a flat panel.  But a part of me always wonders if "all this noisy stuff is introducing some noise in my images that I cannot see"?   There are so many things we can do to mess up astro captures, it is very easy to be paranoid.  Murphy really is always after us. 

Which brings up this question:   Are these things any use in astrophotography? 

https://powerwerx.com/dc-line-noise-filter-powerpole-connectors

I think it's specifically aimed at noise in ham radios, I have no idea if it even filters the kind of noise we can get from PWM in a dew heater, or random noise from a NUC.  I've also got a bunch of ferrite cores I put around wires, but I am told they rarely actually do any good (but they are cheap and do no harm). 

But there is a point where I have to say "if I do not see  a problem, there isn't a problem" and actually take some images.  :) 

Linwood


Emilio J. Robau, P.E.
 

That powerwerx device looks pretty good.  Being as paranoid as I am, that looks like a good candidate for my camera power supplies.  Curious to see the groups response to that device.


thefamily90 Phillips
 

I have been using one for over 6 months. Works well with my AP1200 go to Mount. Just purchased a second one.

JimP 


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Emilio J. Robau, P.E. <ejr@...>
Sent: Monday, January 10, 2022 3:24:18 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] Separate power for mount - why?
 
That powerwerx device looks pretty good.  Being as paranoid as I am, that looks like a good candidate for my camera power supplies.  Curious to see the groups response to that device.


ap@CaptivePhotons.com
 

On Mon, Jan 10, 2022 at 03:35 PM, thefamily90 Phillips wrote:
I have been using one for over 6 months. Works well with my AP1200 go to Mount. Just purchased a second one.
How do you know that it does anything?  (You're talking about the DC filter, right?)

Note I am not saying it does NOT do anything, I just wonder how one evaluates such (absent a 'scope, and even with one, how do you know what kind of noise causes issues)?

Linwood


Emilio J. Robau, P.E.
 

Adding to Linwood's reply, you are using it on the power supply to the mount, yet that seems to be much less sensitive to noise.  Should you not be using it for the camera supplies.   I did not do well in my EE classes and is probably why I am a civil engineer.  Ironically I did great in hydraulics.


Joseph Beyer
 

I’ve been using the same power supply for at least 3 years for the mount, camera and heaters.  I’ve got two supplies but only use one at a time to power the entire rig.  I’ve never noticed any difference in the images when running heaters or when using the mount on one versus powering everything from one supply.  Could be my Nikon D800 and ASI6200 are more resistant to any interference or noise created by the supplies.  

On Jan 10, 2022, at 1:25 PM, Emilio J. Robau, P.E. <ejr@...> wrote:

Adding to Linwood's reply, you are using it on the power supply to the mount, yet that seems to be much less sensitive to noise.  Should you not be using it for the camera supplies.   I did not do well in my EE classes and is probably why I am a civil engineer.  Ironically I did great in hydraulics.


Peter Nagy
 

I always use one power source to power the following for about 10 years: 

A-P Mach1 and currently A-P 1100GTO using CP3 and currently CP4
SXVR-M25C, then QSI660wsg and currently QHY600M cameras
Optec Focus Boss II auto focuser 
USB hub
Ethernet switch 

Peter


jimwc@...
 

On Mon, Jan 10, 2022 at 10:55 AM, ap@... wrote:
Linwood & all
you guys are talking about (A, and the power supply) no ware was there a mention of a model number for the power supply you are talking about. I am assuming the power supply you are talking about is the 13.8V nonadjustable voltage model. Am I correct?
Jim  


Joseph Beyer
 

Jim,

I was referring to the Powerwerx 25 amp variable voltage supply that is also available from Astro-Physics - https://www.astro-physics.com/psvpw25a

Joe

On Jan 10, 2022, at 5:11 PM, jimwc@... wrote:

On Mon, Jan 10, 2022 at 10:55 AM, ap@... wrote:
Linwood & all
you guys are talking about (A, and the power supply) no ware was there a mention of a model number for the power supply you are talking about. I am assuming the power supply you are talking about is the 13.8V nonadjustable voltage model. Am I correct?
Jim  


thefamily90 Phillips
 

Yes, that is the one I use and is also the second one I ordered. 

JimP


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Joseph Beyer <jcbeyer2001@...>
Sent: Monday, January 10, 2022 8:18:52 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] Separate power for mount - why?
 
Jim,

I was referring to the Powerwerx 25 amp variable voltage supply that is also available from Astro-Physics - https://www.astro-physics.com/psvpw25a

Joe
On Jan 10, 2022, at 5:11 PM, jimwc@... wrote:

On Mon, Jan 10, 2022 at 10:55 AM, ap@... wrote:
Linwood & all
you guys are talking about (A, and the power supply) no ware was there a mention of a model number for the power supply you are talking about. I am assuming the power supply you are talking about is the 13.8V nonadjustable voltage model. Am I correct?
Jim  


jimwc@...
 

Thanks for the clarification. One person is using a variable voltage and one using a non-variable voltage model they both work equally well as a separate power supply. 
Thanks
Jim 


ap@CaptivePhotons.com
 

On Mon, Jan 10, 2022 at 08:29 PM, <jimwc@...> wrote:
One person is using a variable voltage and one using a non-variable voltage model they both work equally well as a separate power supply. 
I use the variable one also, though I use it at the fixed 14.1 voltage.   I think the other one is a similar technology just with powerpoles and fixed voltage; I do not know if it existed when I ordered. 


Woody Schlom
 

Joseph,

 

And the non-adjustable Powerwerx is actually slightly variable inside the case.  I believe they ship set to 14.1v.  But I followed their instructions and went inside mine and lowered it to 12.88v – as low as it would go.  I also have and use one of their variable units which has a lot more range.

 

Woody

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Joseph Beyer
Sent: Monday, January 10, 2022 5:19 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Separate power for mount - why?

 

Jim,

 

I was referring to the Powerwerx 25 amp variable voltage supply that is also available from Astro-Physics - https://www.astro-physics.com/psvpw25a

 

Joe

On Jan 10, 2022, at 5:11 PM, jimwc@... wrote:

On Mon, Jan 10, 2022 at 10:55 AM, ap@... wrote:

Linwood & all

you guys are talking about (A, and the power supply) no ware was there a mention of a model number for the power supply you are talking about. I am assuming the power supply you are talking about is the 13.8V nonadjustable voltage model. Am I correct?
Jim