Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Power for Astrophotography rig off grid

  • Please log in to reply
20 replies to this topic

#1 DG_Astro

DG_Astro

    Lift Off

  • -----
  • topic starter
  • Posts: 2
  • Joined: 14 Feb 2021

Posted 03 March 2021 - 04:57 AM

Hi,

 

I'm a newbie in astrophotography, and I would appreciate some guidance on this topic. This is my current equipment:

 

Mount: Celestron AVX

OTA: Celestron reflector 6'', 750 FD, f/5

Camera: Nikon D5500

Guide Camera: ZWO ASI120MC / 60mm guide scope

miniPC: Beelink Gemini M

Router: TP-Link AC750 (TL-WR902AC)

Power box: Pegasus Astro Pocket Powerbox Micro

 

At this point I have everything connected to the power box, it is very convenient that I can modify the voltage of every outlet of the powerbox though software, hence I can have my DSLR connected with 9V, the router connected with 5V and the mount and the mini pc at 12V, right now my consumption should no be higher than 12v 6amp (directly to the powerbox), but considering future purchases of the focuser, CCD camera, filter wheel, dew heather etc I will easily reach the 12v 10 amps that the power box is able to deliver. Now it comes the question, what would be the best approach to deliver 12V 10 amps through the night in the middle of nowhere?

 

I have seen two options:

 

  • Lithium batteries, for example:
    • Orion Dynamo Pro
    • Celestron PowerTank Lithium Pro
    • etc

Comments: These are more expensive, I do not know about how long the charge will last depending on the capacity, and also are not available in my country right now (Chile)

 

Comments: cheaper option, provides enough energy to work though the nigh, and there are some consideration on not draining the battery entirely, fully charge it every time, use it every 3 months or so, etc.

 

 

I would like to read your experience and how are you powering your rig off grid.

 

Thanks in advanced.

 

 



#2 NoDarkSkies

NoDarkSkies

    Viking 1

  • -----
  • Posts: 844
  • Joined: 21 Feb 2020
  • Loc: Denver Metro Colorado

Posted 03 March 2021 - 05:11 AM

Maybe here Mobile power recommendations



#3 Astronut07

Astronut07

    Explorer 1

  • *****
  • Posts: 61
  • Joined: 13 May 2017
  • Loc: Sydney. Australia

Posted 03 March 2021 - 05:32 AM

Gday DG Astro

 

So I have 3x Gel deep cycle batteries 12V ( 100Amp/hr )installed in these portable battery boxes, I bought these from Aldi ( Australia ) 

They have USB & cigarette type outputs, I installed the power monitor devices to gauge power consumption.

I take these units out with me on viewing nights & have never run out of power yet.

I have installed a 600Watt inverter on outside of one of battery packs just for laptop or any 240VAC device I need

 

Good luck

 

Attached Thumbnails

  • 93EAE318-DE5F-439B-A6CB-AF7B3E91FE35.jpeg
  • C622D892-D04E-4A14-AC14-290883789847.jpeg
  • 30462CF9-4B1E-4B01-890B-C992D0EED827.jpeg

  • PirateMike, SonnyE, zakry3323 and 1 other like this

#4 PirateMike

PirateMike

    Soyuz

  • *****
  • Posts: 3,805
  • Joined: 27 Sep 2013
  • Loc: A Green Dot On A Blue Sea

Posted 03 March 2021 - 08:25 AM

If you want to image all night and not worry about power, then what astronut07 does is what you want to do.

 

I understand that these batteries are a bit heavy, and there are three, but that is the way it goes.

 

You can connect them all together so that you have 3 times (in the case of having 3 batteries) the amp hours available and still have a 12 volt supply. You should charge the batteries connected together in the same configuration as when you use them. Number each battery so that you know which is which.

 

You shouldn't run the batteries down past 50% capacity, that will shorten their useful life. 

 

You can measure the usage of your equipment and then determine how big of a battery pack you will need. Ohms Law is the calculation that you will need to use. Google Ohms Law if need be.

 

If you are going to use an inverter to power your computer, I would suggest that you use one that delivers a true sign wave. Be nice to your computer.

 

 

 

Miguel   8-)

 

.


  • Astronut07 likes this

#5 WadeH237

WadeH237

    Fly Me to the Moon

  • *****
  • Posts: 6,904
  • Joined: 24 Feb 2007
  • Loc: Ellensburg, WA

Posted 03 March 2021 - 09:42 AM

Here is what my power system looks like:

 

  • 2 x 75ah AGM Batteries
  • 2 x 150w solar panels
  • MPPT Solar Charge Controller
  • Buck-Boost Converter between Batteries and RigRunner (to supply a constant voltage to the gear)
  • RigRunner distribution to each device

 

This setup runs my portable observatory for an indefinite period of time in the field.  It's not cutting edge like a system built around LiFePO4 batteries, but it is robust and cost effective.  I simply don't think about power with this setup.


  • PirateMike likes this

#6 DG_Astro

DG_Astro

    Lift Off

  • -----
  • topic starter
  • Posts: 2
  • Joined: 14 Feb 2021

Posted 03 March 2021 - 11:07 AM

Thank you for all the replies, I have an answer for many of my newbie questions, now I start thinking and modeling what I need.


  • PirateMike likes this

#7 Jarno

Jarno

    Messenger

  • -----
  • Posts: 415
  • Joined: 22 May 2005
  • Loc: Netherlands

Posted 03 March 2021 - 11:23 AM

Or if you feel a bit adventurous you can build your own powerbox. I managed to do it and I'm a mechanical (strictly nuts-and-bolts type) engineer, not an electrical engineer and apart from a relay with a manufacturing defect I didn't fry a single thing.I started out with gel batteries but one of them died on me after just two years. Once all the parts have come in I'm going to build a new one with LiFePo4 batteries. They're a lot more expensive but once you feel the weight difference - wow!

 

Jarno



#8 rgsalinger

rgsalinger

    Cosmos

  • *****
  • Moderators
  • Posts: 8,172
  • Joined: 19 Feb 2007
  • Loc: Carlsbad Ca

Posted 03 March 2021 - 11:37 AM

I suggest taking a tour through CN and seeing all of the nice projects that people have built over the past few years, particularly with an emphasis on you own Lithium battery pack. 

 

If your budget stretches out, take a look at the Jackery 500 which looks pricey but goes on sale from time to time. Several people seem to be very happy with these. You get double the power rating of AGM cells with LIPO because they can be fully discharged. 

 

Rgrds-Ross


  • PirateMike likes this

#9 PirateMike

PirateMike

    Soyuz

  • *****
  • Posts: 3,805
  • Joined: 27 Sep 2013
  • Loc: A Green Dot On A Blue Sea

Posted 03 March 2021 - 12:01 PM

Thank you for all the replies, I have an answer for many of my newbie questions, now I start thinking and modeling what I need.

Good luck with your power project.

 

Let us know how it goes and what your solution is and what it looks like. We would love to see it. waytogo.gif

 

 

Miguel   8-)

 

.



#10 SonnyE

SonnyE

    Mercury-Atlas

  • -----
  • Posts: 2,984
  • Joined: 01 Nov 2015
  • Loc: Cali for ni a

Posted 03 March 2021 - 12:09 PM

Hi DG!

I'm a big fan of Deep Cycle batteries myself.

If you are backpacking your equipment around, the lithium would be an advantage.

But I tend to travel by truck, so I have plenty of capacity for heavy batteries, plus the 12 volt system of my vehicle as well.

So I use an inverter to run my laptop off my trucks system, and if I need any dew heaters, I'd run those off the truck as well.

But my mount and telescope always got a separate battery so those got clean, noise free power.

I've gone 3 days on a single AGM lead-acid battery running my Mount and Cameras.

But I almost never need dew heaters because most of my time is spent in the South-West American deserts. So it's pretty arid.

 

But always remember your car or truck can help provide part of your needs for field power supply. wink.gif

Just remember car power can be "noisy", so use it for non-critical needs, like dew heaters, or inverters for computer equipment.

(I use a 350 watt sine-wave inverter to run my computer, because it has a 19 volt output to the computer. I can idle my engine to keep the vehicle battery charged.

And ultimately, the AGM Battery can be used to boost to start a drained battery.

 

Take along a solar charger, too. Happy remoting!



#11 Anhydrite

Anhydrite

    Vostok 1

  • -----
  • Posts: 105
  • Joined: 26 Aug 2017

Posted 03 March 2021 - 12:10 PM

To understand how long things will stay powered.....look at the amp hour rating.

 

Your system pulling 10Amps will last 10 hours on a 100 ah battery.....or 20 hours if pulling only 5 amps.  Well if its Lead acid it will last 5 hours pulling 10 amps because you should not discharge past 50% capacity.

 

Li-Ion is better in that regard but it also has issues in cold temperatures and can be a fire hazard if damaged or overcharged.

 

LiFePo4 is a better chemistry for lightweight batteries.  They have long life, lightweight, extremely safe, work way better in cold weather, and can be discharged to use the complete rated amp hour rating so you actually get 100 ah out of a 100 ah battery.

 

They are a bit more expensive then lead acid or deep cycle marine batteries though.  They can be purchased prebuilt or homebuilt. 


  • PirateMike likes this

#12 SonnyE

SonnyE

    Mercury-Atlas

  • -----
  • Posts: 2,984
  • Joined: 01 Nov 2015
  • Loc: Cali for ni a

Posted 03 March 2021 - 12:17 PM

and also are not available in my country right now (Chile)

 

Li-Ion fans take note.


  • PirateMike likes this

#13 rhetfield

rhetfield

    Apollo

  • *****
  • Posts: 1,484
  • Joined: 14 Aug 2019
  • Loc: Suburban Chicago, IL, USA

Posted 03 March 2021 - 01:10 PM

Hi,

 

I'm a newbie in astrophotography, and I would appreciate some guidance on this topic. This is my current equipment:

 

Mount: Celestron AVX

OTA: Celestron reflector 6'', 750 FD, f/5

Camera: Nikon D5500

Guide Camera: ZWO ASI120MC / 60mm guide scope

miniPC: Beelink Gemini M

Router: TP-Link AC750 (TL-WR902AC)

Power box: Pegasus Astro Pocket Powerbox Micro

 

At this point I have everything connected to the power box, it is very convenient that I can modify the voltage of every outlet of the powerbox though software, hence I can have my DSLR connected with 9V, the router connected with 5V and the mount and the mini pc at 12V, right now my consumption should no be higher than 12v 6amp (directly to the powerbox), but considering future purchases of the focuser, CCD camera, filter wheel, dew heather etc I will easily reach the 12v 10 amps that the power box is able to deliver. Now it comes the question, what would be the best approach to deliver 12V 10 amps through the night in the middle of nowhere?

 

I have seen two options:

 

  • Lithium batteries, for example:
    • Orion Dynamo Pro
    • Celestron PowerTank Lithium Pro
    • etc

Comments: These are more expensive, I do not know about how long the charge will last depending on the capacity, and also are not available in my country right now (Chile)

 

Comments: cheaper option, provides enough energy to work though the nigh, and there are some consideration on not draining the battery entirely, fully charge it every time, use it every 3 months or so, etc.

 

 

I would like to read your experience and how are you powering your rig off grid.

 

Thanks in advanced.

I think the real question would be how long you will be in the bush before you can get back to an electrical outlet?  Would your setup be able to get charged in the morning or would it have to run multiple nights.  If running multiple nights, then it might need charging from a vehicle or generator.



#14 t-ara-fan

t-ara-fan

    Surveyor 1

  • -----
  • Posts: 1,754
  • Joined: 20 Sep 2017
  • Loc: 50° 13' N

Posted 03 March 2021 - 01:14 PM

 

You can measure the usage of your equipment and then determine how big of a battery pack you will need. Ohms Law is the calculation that you will need to use. Google Ohms Law if need be.

.

Ohms Law is not the calculation.   The calculation is "current draw in amps" * "hours of use" = amp-hours  needed.  

 

Then there are a few more factors such as lead acid battery cannot be fully discharged. And if you draw high currents you get lower total amp hours than if you draw low currents.


  • PirateMike likes this

#15 rgsalinger

rgsalinger

    Cosmos

  • *****
  • Moderators
  • Posts: 8,172
  • Joined: 19 Feb 2007
  • Loc: Carlsbad Ca

Posted 03 March 2021 - 01:30 PM

I think that the point the OP is making is that the Celestron power packs are not available, not that Chile has some law or regulation concerning the use of Li batteries of all types. If any one has a link showing that Li technology is simply unavailable, just post it and I withdraw my suggestion. 



#16 PirateMike

PirateMike

    Soyuz

  • *****
  • Posts: 3,805
  • Joined: 27 Sep 2013
  • Loc: A Green Dot On A Blue Sea

Posted 03 March 2021 - 02:12 PM

Ohms Law is not the calculation.   The calculation is "current draw in amps" * "hours of use" = amp-hours  needed.  

 

Then there are a few more factors such as lead acid battery cannot be fully discharged. And if you draw high currents you get lower total amp hours than if you draw low currents.

So how does one change watts to amps without using Ohms Law?

 

My dew strips specify watts and not amps, just like a light bulb.

 

 

 

Just wondering?

Miguel   8-)

 


Edited by PirateMike, 03 March 2021 - 02:18 PM.

  • jdupton likes this

#17 jdupton

jdupton

    Gemini

  • *****
  • Posts: 3,182
  • Joined: 21 Nov 2010
  • Loc: Central Texas, USA

Posted 03 March 2021 - 03:26 PM

Miguel,

 

   Yes, absolutely.

 

   Amps = Watts / Voltage

 

   We have to keep in mind that Watts times Hours = Watt-Hours (WH) and Amps times Hours = AH. Both ways need Ohms Law for conversion.

 

<engineer_talk on>

   Always pay attention to units of measure.

 

   I often see many people trying to measure current in A/H or AH. If you say something draws 10 A/H you are really saying that at the end of one hour it is drawing 10 Amps, at the end of two hours it is drawing 20 Amps and at the end of a 10 hour session it is drawing 100 Amps. Obviously our astronomy devices do not behave like that.

 

   A device that draws 10 Amps will have used 10 AH at the end of one hour, and 100 AH at the end of 10 hours. Amps is a rate which can be multiplied by time to give a capacity. It can also be multiplied by voltage and time to give a power capacity like Wh. Multiplying a capacity like AH or WH times time is mostly meaningless in our discussions of batteries and usage / total capacity needs.

<engineer_talk off>

 

   And I agree with your comment. Ohms Law must be used. There are no alternatives! In addition, when using or discussing Lead-Acid batteries, Peukerts Law must also be applied if accuracy is desired. This becomes important when finding the required size / capacity of a Lead-Acid battery.

 

 

John


Edited by jdupton, 03 March 2021 - 07:45 PM.


#18 NoDarkSkies

NoDarkSkies

    Viking 1

  • -----
  • Posts: 844
  • Joined: 21 Feb 2020
  • Loc: Denver Metro Colorado

Posted 03 March 2021 - 05:15 PM

To understand how long things will stay powered.....look at the amp hour rating.

 

Your system pulling 10Amps will last 10 hours on a 100 ah battery.....or 20 hours if pulling only 5 amps.  Well if its Lead acid it will last 5 hours pulling 10 amps because you should not discharge past 50% capacity.

 

Li-Ion is better in that regard but it also has issues in cold temperatures and can be a fire hazard if damaged or overcharged.

 

LiFePo4 is a better chemistry for lightweight batteries.  They have long life, lightweight, extremely safe, work way better in cold weather, and can be discharged to use the complete rated amp hour rating so you actually get 100 ah out of a 100 ah battery.

 

They are a bit more expensive then lead acid or deep cycle marine batteries though.  They can be purchased prebuilt or homebuilt. 

LiFePo4 Batteries have the same issue as all other batteries in the Cold, they have even shown that they last longer than Lead Acid this includes AGM and Gel Batteries as well.
The only issue with LiFePo4 Batteries is when it comes time to charge them, you cannot charge them below 26°F - 28°F and the BMS will not allow them to be charged. If you are making your own LiFePo4 Battery System then you have to add a BMS to you LiFePo4 Battery Build.
Also most if not all GOOD LiFePo4 have a BMS system that would not allow the charge to over charge and cause any kind fire.
They are not the same battery that is used in a SmartPhone.


Edited by NoDarkSkies, 03 March 2021 - 05:25 PM.

  • jdupton likes this

#19 NoDarkSkies

NoDarkSkies

    Viking 1

  • -----
  • Posts: 844
  • Joined: 21 Feb 2020
  • Loc: Denver Metro Colorado

Posted 03 March 2021 - 05:28 PM

Watts convert to AMPs as well as AMPs convert to Watts.

That is why Batteries use Ah in the rating. Watts to Amps or Amps to Watts Links

Like 5 Watts = 0.42 Amps and 5 Amps = 60 Watts and so on

So how does one change watts to amps without using Ohms Law?

My dew strips specify watts and not amps, just like a light bulb.

Just wondering?

Miguel   8-)

 


Edited by NoDarkSkies, 03 March 2021 - 05:31 PM.


#20 Wintersun

Wintersun

    Explorer 1

  • -----
  • Posts: 68
  • Joined: 18 Jan 2013
  • Loc: Elkhorn CA

Posted 03 March 2021 - 07:02 PM

I have used the sealed lead acid batteries sold for use on wheelchairs where high AH are needed. Not too heavy and they can be in any orientation. The lead acid batteries should not be discharged past 50% SOC or their life is greatly reduced.

 

For less demanding applications I use the TalentCell lithium ion battery packs in the 8300mAh size. Great connectivity options and they recharge quickly after use.

 

Ideal are the lithium phosphate which are far less likely to catch fire and destroy a vehicle or ones home. But a 100 AH one sells for $900. Good part is that you can discharge them by 100% and not damage them.

 

Some items like a dew heater are not going to be affected by lower voltage levels and others like a controller need their rated input voltage. Suggest keeping the two types of demand loads separate.



#21 Phil Sherman

Phil Sherman

    Gemini

  • *****
  • Posts: 3,353
  • Joined: 07 Dec 2010
  • Loc: Cleveland, Ohio

Posted 03 March 2021 - 08:43 PM

I believe that your power estimates are a bit high. A focuser and filter wheel actually draw almost no power unless they are actually moving, something that isn't constantly done. Your guide camera, a USB device drawing 0.1A @ 5V (from device specs) will draw less than 50MA at 12V if the Pegasus box uses a buck type converter to produce 5V.

 

I suspect that your Beelink draws 1A @12V or less most of the time. Your TP-Link router appears to have a USB-C power port which indicates a power draw of less than 1A @ 12V. I suspect that when you add the imaging camera and dew heaters, your total average draw at 12V will be less than 8A and is likely to be around 7A. 

 

I'm waiting for the AliExpress vendor I found to get in a new shipment of 50A LiFePO4 12V batteries. Two of them cost a little more than a 100A flooded wet cell lead acid battery. Together, they should have almost the same capacity as 200AH of lead acid batteries and weigh less than a single lead acid battery.




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics