Topics

External Power #starparty #EXOS2 #TECHNICAL


Scott - Moron Astronomer
 

Hi,

I'm looking at this external power source and was wondering if you think it would work fine as an external power source. I'm not an electrical engineer so I don't know what to look for. I'm thinking this would work fine, but just want to double check. I know Explore Scientific has an external battery pack, but I like that this one has other charging ports as well.

https://www.ravpower.com/products/rp-pb055-27000mah-portable-charger

Thanks for any help,

Scott
--
Mounts: ES PMC-8 Exos II
Scopes: ES 127ED
Cameras:  ZWO ASI224MC, Canon Ti7
Controller: Dell Laptop with WIndows 10
Software: Explorestars


Lloyd Simons
 

Scott,

What are you trying to power? Just the mount? If so this is definitely overkill. I have 2 batteries.

 

The smaller one has enough juice to run the mount for several hours. The large one I use for my AP setup. The one you linked to doesn't appear to have a 12v port so you would need to plug in an AC power supply into the 3-prong outlet. It should work though.

--
Lloyd Simons
Mattawan, MI
Telescopes:
 Astrotech AT72ED II, Orion 8" Dobsonian, Tectron 15" Dobsonian
Camera: Canon T3i
Mount: iExos-100 PMC-8
Mount Control: Explorestars on a Lenovo Tab 2 A10-70F Android 6.0


Scott - Moron Astronomer
 
Edited

Thanks Lloyd.

Yes, to power the mount. I'm going on family vacation and was going to buy a battery charger so figured why not get something I can use for more than one application.

I like the second one you posted. So, for astrophotography do you use both batteries listed? One to power mount and the other to power equipment? Or, do you just use the second one to power mount and all your equipment when you do astrophotography?

Scott
--
Mounts: ES PMC-8 Exos II
Scopes: ES 127ED
Cameras:  ZWO ASI224MC, Canon Ti7
Controller: Dell Laptop with WIndows 10
Software: Explorestars


Lloyd Simons
 

Scott,
I have not tried to use everything on a single battery yet but I think it has enough power to work for a few hours.

Lloyd



--
Lloyd Simons
Mattawan, MI
Telescopes: Astrotech AT72ED II, Orion 8" Dobsonian, Tectron 15" Dobsonian, Celestron Super Polaris C8
Imaging Camera: Canon T3i
Guide Camera: QHY5L-IIM with a 100mm CS Mount Lens
Mounts: iExos-100 PMC-8, Vixen Super Polaris
Mount Control: KODLIX gn41 mini PC, Explorestars on a Lenovo Tab 2 A10-70F Android 6.0
Software: N.I.N.A. for imaging, PHD2 for guiding, Sharpcap for PA, Cartes du Ciel, PixInsight


Wes Mcdonald
 

Scott

The PMC8 needs about .5 amps.  A battery with a capacity of 5000 ma hours (milliamp hours) or 5.0 amp hours will run the mount for about 5/.5 or 10 hours.  Now derate this by about 50% for safety and you have 2.5 hours.   A battery with 25000 ma hours would provide 25/.5 or 50 hours...derate by half and get 25 hours.  Pretty impressive.  

The thing is when you are observing you will need dew heaters in summer and sometimes in winter too.  These things will pull about 2 amps at least for the main objective and the eyepiece.  Then you need one for the guide scope and maybe two for your finder scope so that's another 2 or three amps.  So say you need 4 amps of dew control.  All of a sudden the 5000 ma battery looks dead in 5/4.5 or about an hour.  The 25000 ma hr one is done in 5 without derating.  So expect less.

I have a huge lead acid battery solution so I never worry.  (100 amp hours...haha at 40 pounds).  But I would surely go with as big a battery as you can afford.  But be careful these big lithium batteries might not be able to be carried on aircraft...as in taken in vacation with you.   So check that out.  In fairness I haven't and won't haul my lead acid along on a flight...probably couldn't anyhow.

Don't plan on using an ac-dc adapter powered by a battery (which has a built in 120 volt inverter) as this will be a huge power waster.  I would imagine you would suffer huge reductions in use time.  Be sure to get a battery which has a built in 12v output capability.

Wes





--
Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired


 

Scott,
 
It really depends on how much power you plan on drawing, and for how long, and at what voltage, and at what temperatures.
 
My setup (AP-only, PMC8, DewNot dew heaters, usb hub, DSLR, Guide camera) bounces around a bit, but on average draws not much more than 1A.  Really pretty frugal - the DewNots are not power hogs, and a little heat goes a long way, at least for me.  My power is measured and distributed by a Pocket Powerbox (which also controls the heaters), and I really do not want to run my overall setup below 11v.
 
I read all the glowing reports about Talentcells on CN and picked up their 12v/11000mAh model.  Charged it up, and it dropped below 11v on me, after couple of hours.  In June, not winter.  
 
Basically, it still had lots of power left, but only at lower voltages.  If I'd been charging USB devices off it, it would have been a different story.  It wasn't so much the total power the battery could store, as whether it could maintain that at the voltage I needed over time.  That voltage drop seems to be a feature of Lithium-ion batteries as a species.  As far as I can tell, the Talentcells are good Li-ions, but they're still Li-ions...
 
After figuring out what was going on, I returned the Talentcell, and got a battery from another mfr, using LiFePo4 technology.  Much flatter voltage when discharging, and sadly, more expensive.  I've done 6+ hour sessions so far, in colder temps, with it still holding in the high 11's (voltage).  I do not know how much farther out the failure point is, but so far, good enough for me - although I may need to wrap it up with a handwarmer when we get down into the -10/-15C range.  First winter coming, so we'll see.  
 
So...think about your requirements and be cautious about capacities and voltages.  I went for LiFePo4 because I did not want the weight of a lead-based battery, but if I had larger power or endurance requirements in my environmental conditions (winter is coming...), I think I'd have to go to lead.
 
FWIW...
 
- Bob
 
--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2-IMX224C
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


Steve Siedentop
 

Hi Scott -

Painful experience has taught me to have my imaging camera/cooler, computer, and dew heaters on one power source and the mount on another.  The product you referenced has a capacity of 27 amp hours, but they’re not clear how they calculated that.  I’m betting that’s 27 amp hours at 5 volts rather than 12.

The Explore Scientific Power Bank will run my PMC-8 G-11 for about 7 hours, which is long enough for most of my imaging sessions.  For the rest of my gear, I built a battery box for a 100 amp hour Group 31 deep cycle battery.  They’re cheap when you consider the capacity you’re getting, but they’re fairly heavy.

I would recommend you avoid using an inverter to run your gear off of an ac power supply.  Everything we typically use runs off of dc.  Converting dc (your battery) to ac using an inverter and converting it back to dc using a wall wart or other power supply is a waste of energy.  You’ll even find dc chargers, sometimes called car chargers, for your laptop on Amazon.  Go with the PWR brand if you go that route.  They’ve never let me down.

If you’re the DIY type, I’ll be happy to send you plans and a parts list for the battery box I built.  It’s not hard and you’ll be able to put it together in an afternoon.  You’ll end up with a finished product that meets your needs better than anything you could buy.

-Steve

On Sat, Nov 9, 2019 at 12:43 PM Scott - Moron Astronomer <allstar@...> wrote:
Hi,

I'm looking at this external power source and was wondering if you think it would work fine as an external power source. I'm not an electrical engineer so I don't know what to look for. I'm thinking this would work fine, but just want to double check. I know Explore Scientific has an external battery pack, but I like that this one has other charging ports as well.

https://www.ravpower.com/products/rp-pb055-27000mah-portable-charger

Thanks for any help,

Scott
--
Mounts: ES PMC-8 Exos II
Scopes: ES 127ED
Cameras:  ZWO ASI224MC, Canon Ti7
Controller: Dell Laptop with WIndows 10
Software: Explorestars


--
Mounts: ES PMC-8 G11 with Ruland Couplers and One Piece Worm Blocks, Skywatcher NEQ-6
Scopes: ES ED127CF FCD100, Orion 6” Mak, Stellarvue SV80EDT, Coronado Solarmax 40
Cameras:  CentralDS CDS-600, CentralDS Astro 60D, Orion Starshoot SSAG
Msc: Moonlite Focusers, Astrozap Dew Straps, Pegasus Ultimate PowerBox
Software: PixInsight, Cartes du Ciel, BackyardEOS, SkySafari


Jim McKee
 

I have also been exploring battery options.    I found this article to be good background if you want to compare lead-acid battery technologies.:

http://cfas.org/data/uploads/astronomy-ebooks/batteries.pdf

--
Scope:        Orion EON 115mm APO
Mounts
:      ES EXOS2-GT w/ PMC-8
Cameras:   Canon 6D Mk 2, Canon 7D2, 1D Mk 2, EOS 60D Asto Modified
Lens:
          Canon EF 100-400mm f/4.5-5.6L IS II
Misc:          TELRAD, ZWO ASI120MM Guide Camera, Astromania 60mm Guidescope, Senso Sesto Focus Motor
Software:   EXPLORESTARS IOS & WIN, Stellarium. NINA,  APT, DSS, PixInsight, Photoshop CC
Computer:  Dell Latitude E5450, Windows 10


Steve Siedentop
 

Great find, Jim!

There’s a relatively recent addition to the battery technology mix using Lithium-Iron-Phosphate chemistry, sometimes listed as LiFePo4 in marketing literature.  The benefits are weight & size, shelf life, and safety.  The two recent iterations of the Celestron PowerTank use such a battery and the Explore Scientific power bank might as well.  The downside, because there’s always a downside, is cost.  I priced a 100 amp-hour LiFePo4 deep cycle for solar applications and the price was over $1,100.00.  Even with all the benefits and 15 pound weight, I couldn’t justify the cost compared to my 100 amp hour, high-maintenance, 50 pound, Group 31 deep cycle AGM battery.

The price will come down on LiFePo4 batteries, so they’re something to keep on your radar.

-Steve

On Sun, Nov 10, 2019 at 8:17 AM Jim McKee <mckeejh@...> wrote:
I have also been exploring battery options.    I found this article to be good background if you want to compare lead-acid battery technologies.:

http://cfas.org/data/uploads/astronomy-ebooks/batteries.pdf

--
Scope:        Orion EON 115mm APO
Mounts
:      ES EXOS2-GT w/ PMC-8
Cameras:   Canon 6D Mk 2, Canon 7D2, 1D Mk 2, EOS 60D Asto Modified
Lens:
          Canon EF 100-400mm f/4.5-5.6L IS II
Misc:          TELRAD, ZWO ASI120MM Guide Camera, Astromania 60mm Guidescope, Senso Sesto Focus Motor
Software:   EXPLORESTARS IOS & WIN, Stellarium. NINA,  APT, DSS, PixInsight, Photoshop CC
Computer:  Dell Latitude E5450, Windows 10


--
Mounts: ES PMC-8 G11 with Ruland Couplers and One Piece Worm Blocks, Skywatcher NEQ-6
Scopes: ES ED127CF FCD100, Orion 6” Mak, Stellarvue SV80EDT, Coronado Solarmax 40
Cameras:  CentralDS CDS-600, CentralDS Astro 60D, Orion Starshoot SSAG
Msc: Moonlite Focusers, Astrozap Dew Straps, Pegasus Ultimate PowerBox
Software: PixInsight, Cartes du Ciel, BackyardEOS, SkySafari


Jim McKee
 

Steve,
Good to hear that you are using and AGM battery.  I think that is the direction I will go/.
--
Scope:        Orion EON 115mm APO
Mounts
:      ES EXOS2-GT w/ PMC-8
Cameras:   Canon 6D Mk 2, Canon 7D2, 1D Mk 2, EOS 60D Asto Modified
Lens:
          Canon EF 100-400mm f/4.5-5.6L IS II
Misc:          TELRAD, ZWO ASI120MM Guide Camera, Astromania 60mm Guidescope, Senso Sesto Focus Motor
Software:   EXPLORESTARS IOS & WIN, Stellarium. NINA,  APT, DSS, PixInsight, Photoshop CC
Computer:  Dell Latitude E5450, Windows 10


 

I ended up with a Power Tank Pro - a LiFePo4.  It was expensive, but the discharge voltage is much flatter over time than Li-ion, and for my setup I haven't found the endurance limit yet.  All I know is that for the ambient temps I have used it at so far, the limit is TBD, and somewhere beyond 6hr.  And if I wanted to travel with it, it's FAA-approved for carry-on.
 
But I think this only works because my power needs are modest.  If you were to throw, say, a cooled camera into the mix rather than a DSLR, that would be a whole different problem - and the answer would probably be lead.

- Bob
 
--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2-IMX224C
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


Wes Mcdonald
 

Like Steve, I built my astro power supply from a deep cycle marine lead-acid.  It is 110 amp-hour I think.  There is nothing like just loading up the power supply and going forward with no power worries.  

I keep it on a battery conditioner/charger between uses.  My setup includes many different output connectors, including high output USB jacks, etc.  Although anyone starting out should [probably employ Anderson power pole connectors, for their main power use, I used the venerable and terrible car cigar lighter adapters.  I also have a metering system that displays the voltage, current, watts, and amp-hours drawn.  Its really handy to have that information, especially the amp-hours so you know where you are.  

These big batteries are really overkill for the drive mechanisms but are pretty much a necessity for dew heating, TE cooling of cameras, charging lap tops, running cameras, charging phones, operating a local wireless router...all the danged electrical equipment you might need in the field.  Also, since the supply is deep, I keep a 12-120v inverter just in case there is something that needs 120...I don't like to use it, but at least efficiency loss is not a disaster given the size of the power tank.

My battery has lasted over 5 years, and shows no sign of giving up anytime soon.

Instructions for building these things are all over the internet.

Wes.


--
Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired


Mark Christensen
 

Friends,

 

If you want to see some off-the-shelf (kits or finished) of battery boxes with meters, connectors, power converters, and so on just search on “Trolling Power Center” in Amazon. If nothing else the results will give you an idea of what people are talking about and what such gadgets should cost outside of the astro-market.

 

Like Wes, if I was building mine today I would use power poles instead of cigarette power plugs.

 

You can build or buy one of these along with a deep-cycle battery (mine has lasted over 8 years) for about the same as a 17AmpHr “power tank”, esp. this time of year when marine batteries are often on sale (at least up here in the frigid north). And when the battery does go bad it will be trivial to replace it. Some of the astro-market-specific  Power Tanks are really a pain to take apart – Google on “Replacing Power Tank Battery”. Lots of screws and connectors.

 

They fail because of the cheap chargers often supplied with them can cook the battery, by the way. If you read their instructions you’ll see the warning. The solution is to get a good charger that goes into float mode. Cheap insurance.

 

Regards,

 

Mark Christensen


Scott - Moron Astronomer
 

This has been a fun discussion to follow. I appreciate all the input.

For my personal situation, I think I am leaning towards Lloyd's suggestion. I am not at the point I want to build something. I am also fortunate enough to not have to worry about dew. Maybe if I were more hard core in the winter, but I definitely don't have to worry in the warmer months. That's not to say in the future I won't hit you all up on building something, but for now I just want something easy.

Thanks again,

Scott
--
Mounts: ES PMC-8 Exos II
Scopes: ES 127ED
Cameras:  ZWO ASI224MC, Canon Ti7
Controller: Dell Laptop with WIndows 10
Software: Explorestars


Mike Leemhuis
 

I have been reading everyone's battery suggestions and I thought I would add a bit of data to the mix.

I installed a power meter on my PMC-8 Exos2 so that I could see my total current draw from 12 volts.  I am powering 2 heater strips, the PMC-8 box, my TEC camera (QHY163c) and a guide camera (QHY5L-ii).  The current draw is 3.5 amps maximum with 100% TEC power applied.  When I turn off TEC cooling my current draw is 1.6A.  Obviously, TEC cooling takes a lot of power!  The two heater strips are using 0.7A.  So to power my rig for say 6 hours it would take a 6*3.5 = 21 A hr.  Without TEC it would be 6*1.6 or 10A hr.  Hopefully this will give you some ballpark numbers to use when choosing a battery size.

Hope this helps,
Mike


--
Mount: Explore Scientific Exos-2
Scope: Explore Scientific ED102CF
Camera: QHY163C
Filter: Optolong L-eNhance 2" for nebula pictures
Software: ASCOM, PHD2, CDC, Sharpcap Pro
Computer:  Dell desktop XPS
Extras:  Lots of 3D printed parts I designed to improve usability


@JohnDT
 

I see this thread dates back to November but wanted to make a suggestion / query:
Lithium batteries are affordable (compared to LiFePO4) and small enough to carry onto an aircraft (thinking - solar eclipse trip).
The problem is that they discharge reducing their output voltage. My TalentCell 6000mAh is down to 10.4V at 50% charge.
Here is a suggestion: Use a Buck Boost converter. These cost around £12 GBP on Amazon plus a small project box to put it in.
My question is whether the EXOS-100 PMC-Eight mount is compatible with these converters as they control the voltage by Pulse Wave Modulation.
Does anyone know?? 


Skull HQX
 

This will depend on the capability of such a converter. 

I’ve tested with a big powerbank that has a 9 and 12V output option and that seemed to work. On average the power draw was about 5W nominal if I remember correctly.

I’ve also tested with a couple smaller powerbanks and two larger ones, that only have USB out and plugged in a ‘standard’ USB to 12V adapter cable. For some of those powerbanks it would boot the mount and WiFi could be connected. For some that even didn’t work. Working the mount proved unstable or impossible. 

So the only real option would be a good quality powerbank that has a 12V output that can provide enough (peak) power.

Be aware your cable needs to have the correct polarity at the mount. I’m not sure if the mount has a robust reverse polarity protection but you don’t want to find out the hard way!

Clear skies.

Op za 8 feb. 2020 om 12:07 schreef <johntolliday433m@...>

I see this thread dates back to November but wanted to make a suggestion / query:
Lithium batteries are affordable (compared to LiFePO4) and small enough to carry onto an aircraft (thinking - solar eclipse trip).
The problem is that they discharge reducing their output voltage. My TalentCell 6000mAh is down to 10.4V at 50% charge.
Here is a suggestion: Use a Buck Boost converter. These cost around £12 GBP on Amazon plus a small project box to put it in.
My question is whether the EXOS-100 PMC-Eight mount is compatible with these converters as they control the voltage by Pulse Wave Modulation.
Does anyone know?? 


Jerry Hubbell - Explore Scientific VP Engineering
 

On Sat, Feb 8, 2020 at 06:20 AM, Skull HQX wrote:
I’m not sure if the mount has a robust reverse polarity protection but you don’t want to find out the hard way!
Yes, the mount controller has reverse polarity protection on the 12 Vdc input power. The connector is 2.1 x 5.5 mm with the pin at 12 Vdc.
https://www.digikey.com/products/en?keywords=CP-037A-ND

Jerry Hubbell
Vice President of Engineering

Explore Scientific, LLC.
jrh at explorescientific.com

www.explorescientificusa.com
1010 S. 48th Street
Springdale, AR 72762
1-866-252-3811

Author: Scientific Astrophotography: How Amateurs Can Generate and Use Professional Imaging Data
             Remote Observatories for Amateur Astronomers: Using High-Powered Telescopes From Home


Mark Slade Remote Observatory (MSRO) IAU MPC W54 Equipment
Wilderness, VA
Mounts
: ES PMC-Eight G11 + Telescope Drive Master (TDM)
Scopes: ES 165 FPL-53 ED APO CF, ES 102 FCD100 ED APO CF
Cameras:  QHY174M-GPS + FW, QHY163C
Misc: 3-inch 0.7x Focal Reducer Field Flattener, Filters: Luminance,
Red, V-band Photometric, Diffuser, 200 lpmm Spectral Grating

Software: MaxIm DL 6, Cartes du Ciel, Astrometrica, AstroImageJ, AutoStakkert!


Wes Mcdonald
 

Pin is positive 12v.
Wes

--
Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired


Skull HQX
 

Thanks Jerry,

It's good to know it has reverse polarity protection. But I'm not going to test it!

Last year I blew up a €400 synthesizer because I mistakenly plugged in a feed that actually was 9V center-pin negative. Most guitar fx pedals use 9V center-pin negative and the plug is the same 2.1x5.5mm one a lot electronic music instruments use. Those guitar fx pedals are used with synthesizers btw. I can't play guitar and it even can be argued I can't play keys! But I digress.

Strangely my most expensive guitar fx pedal, an Eventide H9 Max, is center-pin positive with a 2.5x5.5mm barrel, but it fits the 2.1x5.5mm plug... So what could possibly go wrong. Yeah, I also managed to blow up that one some time after that first mistake. No working reverse-polarity protection on that thing either! And that is a €700 device. I was mad at myself (something like that never happened to me before in my life) but after ordering a 25ct SMD part I could easily repair it. The synthesizer though... I could bring it back to life (took an ever cheaper part) and even get it to boot, but part of the processor that holds the programming was dead and couldn't hold a reflash. I gave up repairing it.

Since then I have color coded all plugs and leads. And never again will assume a device has a robust reverse-polarity protection! :-)

Clear skies!
 

On Sat, Feb 8, 2020 at 5:37 PM Jerry Hubbell - Explore Scientific VP Engineering <jrh@...> wrote:
On Sat, Feb 8, 2020 at 06:20 AM, Skull HQX wrote:
I’m not sure if the mount has a robust reverse polarity protection but you don’t want to find out the hard way!
Yes, the mount controller has reverse polarity protection on the 12 Vdc input power. The connector is 2.1 x 5.5 mm with the pin at 12 Vdc.
https://www.digikey.com/products/en?keywords=CP-037A-ND

Jerry Hubbell
Vice President of Engineering

Explore Scientific, LLC.
jrh at explorescientific.com

www.explorescientificusa.com
1010 S. 48th Street
Springdale, AR 72762
1-866-252-3811

Author: Scientific Astrophotography: How Amateurs Can Generate and Use Professional Imaging Data
             Remote Observatories for Amateur Astronomers: Using High-Powered Telescopes From Home


Mark Slade Remote Observatory (MSRO) IAU MPC W54 Equipment
Wilderness, VA
Mounts
: ES PMC-Eight G11 + Telescope Drive Master (TDM)
Scopes: ES 165 FPL-53 ED APO CF, ES 102 FCD100 ED APO CF
Cameras:  QHY174M-GPS + FW, QHY163C
Misc: 3-inch 0.7x Focal Reducer Field Flattener, Filters: Luminance,
Red, V-band Photometric, Diffuser, 200 lpmm Spectral Grating

Software: MaxIm DL 6, Cartes du Ciel, Astrometrica, AstroImageJ, AutoStakkert!