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

Yet Another Field Power Battery Box Project

accessories astrophotography
  • Please log in to reply
20 replies to this topic

#1 jdupton

jdupton

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1719
  • Joined: 21 Nov 2010
  • Loc: Central Texas, USA

Posted 26 June 2019 - 10:38 AM

   I have just completed (less a few cosmetic additions) a new Field Battery Supply for my imaging setup. It is an evolution of my older unit I built almost ten years ago. That older unit used a 60 Amp-Hour Spiral AGM Optima battery. Unfortunately the whole field power box weighed about 65 pounds. It provided two separately switched "halves" with four 12 volt automotive style power outlets. The old power box has served me well but after ten years of use, the Optima battery has lost more than 40% of its original capacity.

 

OptimaBox_CTEK.jpg
Photo of Older Field Power Source (with CTEK charger).

 

   I wanted to add some features to my new Field Power Box. As before, I wanted to include two separately switched "sides" for power outlets. In addition, other features I wanted to include:

  • Safety Master switch for the whole power box.
    My previous box had the power switch(s) accidentally turn on a couple of times during transport when I had too much other equipment loaded into the car. Other equipment could bump against the rocker switches during transport. Although nothing was connected to the outlets during transport, I always felt this was a safety concern. The new box includes a Keyed Master Power switch for additional safety.
     
  • Safe LiFePO4 battery technology.
    I chose a BattleBorn 100 Amp-Hour battery for this new version of field power supply. In addition to being the reasonably safer LiFePO4 technology, BattleBorn appears to have (from their detailed specifications) a more robust BMS (battery management system) built in. Their batteries (and BMS) can also be safely charged from a normal automotive charger. 
     
  • High overall battery capacity of ~100 Amp-Hours usable.
    BattleBorn rates their batteries as the deliverable capacity rather than the raw total capacity of their cells. In other words, their 100 Amp-Hour batteries will deliver 100 AH of usable capacity even though the BMS still holds back a reserve to keep from damaging the cells. Many other similar batteries rate based on per the cell total and thus a 100 AH battery may only deliver 85 to 90 AH because their BMS holds the rest in reserve.
     
  • Battery condition monitor so that total power usage from the battery can be directly read.
    Commonly used battery monitor which reads Voltage, Current, Watts, and Cumulative Capacity Used (Watt-Hours).
     
  • Separate Fused Charger Pigtail.
    Like my previous power box design, I included a hardwired pigtail connection for my external charger. I use a NOCO Genius 7200 charger for this battery whereas my previous Optima was hardwired for use with my CTEK 7002 charger.
     
  • Two separately switchable regulated voltages -- ~12.6 volts and ~13.4 volts.
    I wanted to use about 13.2 to 13.4 volts for most of my astronomy equipment. In addition, I wanted to have 12.4 to 12.6 volts available for "computer" equipment that is subject to a 12v +/- 5% specified voltage range. Each regulated voltage powers 3 separately fused outlets at the back of the box.
     
  • Real-time display of current and voltage for each regulated voltage.
     
  • Two high current outlets at nominal battery voltage.
    These two outlets are used for higher current (or noisy) accessories. I will use one to run my laptop and the other to run dew heaters (in the future). (Noise feedback from either is isolated from the regulated voltages above.)
     
  • Two USB 2.1 Amp charger ports plus one high power USB QuickCharge 3.0 port.
    I have a couple of accessories that use 5.0 volt power while imaging and wanted USB ports to power those. I also wanted to include a QuickCharge 3.0 USB charger port for my cell phone and tablet, if needed.
     
  • Separately fused outlets for regulated voltages.
    I wanted to add separate fuses on the regulated voltage outlets so that a single blown device fuse would be less likely to crowbar the power supplies and drop power to a whole side. Hopefully, this will provide a more controlled, graceful shutdown of the power system in the event of a power fault.

 

   Below are two photos of the (nearly) finished unit. I still need to add a few minor touches like Velcro seals to hold the top of the box on more securely and red taillight tape to dim down the voltage displays and Battery Monitor LCD.

 

IMG_0016.jpg

Photo of (nearly) Completed Field Power Box.

 

 

IMG_0020.jpg
Photo of Internal Components and Wiring of Field Power Box.

 

   I am currently load testing the power box to make sure the CPU cooling fans I added to the regulator modules are sufficient to prevent thermal shutdown at maximum current. There is quite a bit of spare air space in the top already and I can feel a slight breeze when at the side louvered vents when power is on. If thermal shutdown is found in my stress testing, I plan to add one more fan to bring in air at one of those vents and let it exit through the others for additional cooling and circulation of outside air into the box.

 

   Because of the fans, synchronous DC-to-DC converter / regulators, battery condition monitor, and USB power ports, there is a steady state no-load parasitic draw on the battery of 0.25 Amps when the unit is powered on. I am satisfied with that since I still have enough power for my whole imaging set-up to run for about 20+ hours. That will typically get me through two to three nights of imaging.

 

   I do like the weight reduction accomplished by using the Lithium battery. The weight of the new unit is about 1/2 of the previous power box and yet has more than 3 times the power capacity. The biggest downside is cost. In addition to the cost of a large LiFePO4 battery, the two synchronous DC-to-DC converter / regulators, voltage current monitors, battery monitor, and USB chargers all added up to an expensive project. I should easily get at least another ten years of use from this new Field Power Box.

 

 

John


Edited by jdupton, 26 June 2019 - 11:13 AM.

  • psandelle, BlueGrass, james7ca and 9 others like this

#2 jerahian

jerahian

    Messenger

  • *****
  • Posts: 437
  • Joined: 02 Aug 2018
  • Loc: Maine

Posted 26 June 2019 - 10:58 AM

Wow, that is one secksy build!  I have zero electrical skills, but can something like this be articulated enough (parts list, diagram, build steps) for a novice to follow along and build?  If so, I'm not sure if you're interested in doing that, but would there be a site or sites I can refer to learn how to build one?

 

I checked your site BTW...you got some great info on there.  Thanks for sharing (and teasing me with) this waytogo.gif

 

-Ara 



#3 kisstek

kisstek

    Ranger 4

  • *****
  • Posts: 312
  • Joined: 25 Jul 2018

Posted 26 June 2019 - 11:11 AM

That's a nice looking project! I'm still trying to figure out what's what in the photo.

 

Is the LiFePO4 battery in the lid or is that the BMS? But there's a key switch and a bunch of meters in the lid too. Hmm.

 

And what are the six black barrel things across the back? Are those your output sockets? There is one on each side and two in the front also.

 

Wait! Do I have everything backwards? The lid is lying in the front of the picture? That would make more sense. Some of those black barrels are meters then. I'm still guessing the 6 along the back are outputs.

 

Are you going to do a write up of the build? It's definitely an impressive build!



#4 james7ca

james7ca

    Fly Me to the Moon

  • *****
  • Posts: 7013
  • Joined: 21 May 2011
  • Loc: San Diego, CA

Posted 26 June 2019 - 11:15 AM

That's a really nice setup, but you forgot an important detail, the approximate cost.

 

I just recently completed (mostly) my own mobile power solution using three, fairly small, 35AHr AGM-style batteries that can either be run separately or in parallel. One battery is enough to power my cameras and all of my computer equipment for two nights in the summer or one very long night (and then some) in the winter. Each battery box has a few leads terminating in PowerPole connectors and those can be connected to my separate, fused, PowerPole junction box which can then be connected individually to 12VDC and 19VDC regulators (the latter for my mini computer).

 

Not nearly as integrated as your setup, but I can also add a multi-meter (with PowerPole input/output connectors) between any of the outputs (entire battery, regulator, single device, etc.).

 

One reason I went this route is that I didn't want a single point of failure. If something happens to one of the batteries I can just use my "spare" and if I need more uninterrupted capacity I can just hook two in parallel. I run the mount on the third battery (without regulation). Only thing I'm missing is capacity for dew heaters, but those are VERY rarely needed in the local mountains or deserts. And, in any case I can always use my "spare" (of the three) for the dew heater. Having three small batteries is also easier to carry (one at a time, each battery unit is about 25 pounds).

 

Oh, in terms of cost, I recall that each battery was about $100 (35AHr, sealed AGM, deep cycle), the PowerPower junction box was $58, the battery boxes (3) where each about $10, the voltage regulators were about $20 each (sealed, weather proof, about 60W each), and then there was wire, extra fuses, and some terminals and connectors for the batteries and some other hardware and that could have been about $100. The multi-meter (which also does a running accumulation of WHrs) was $15.

 

So, total (gulp) was about $550 (plus tax). It took me over one year to get this all together (not purchased at the same time) and as an extra I also purchased a nice A/C inverter which I can also use during power outages at home. I don't plan on using the inverter in the field, unless I get something that requires an odd power input.

 

If push comes to shove I also have a larger, flooded, deep-cycle battery that I've used for several years that could be used in an emergency (since it just needs to be connected via the PowerPoles).

 

Okay, but your setup looks VERY well done. In fact, I'm kind of jealous. grin.gif


Edited by james7ca, 26 June 2019 - 12:16 PM.

  • BHPR likes this

#5 jdupton

jdupton

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1719
  • Joined: 21 Nov 2010
  • Loc: Central Texas, USA

Posted 26 June 2019 - 11:24 AM

Ara,

 

Wow, that is one secksy build!  I have zero electrical skills, but can something like this be articulated enough (parts list, diagram, build steps) for a novice to follow along and build?  If so, I'm not sure if you're interested in doing that, but would there be a site or sites I can refer to learn how to build one?

 

   Thanks. Yes, at some point, I will probably get the build and parts list all written up for my Website in the future. It will take quite some time, though, as I still have other projects in the works. Writing a complete Web article is a like a project in itself if I do it up right.

 

   There are likely some very detailed Web articles on similar builds but it might take some deep searching to find them.

 

 

John


  • BHPR likes this

#6 kisstek

kisstek

    Ranger 4

  • *****
  • Posts: 312
  • Joined: 25 Jul 2018

Posted 26 June 2019 - 11:32 AM

That's a really nice setup, but you forgot an important detail, the approximate cost.

For some reason the old saying "If you have to ask, you can't afford it." came to my mind. smile.gif

 

"Afford" being different for everyone, of course.


  • jdupton likes this

#7 epdreher

epdreher

    Viking 1

  • ****-
  • Posts: 895
  • Joined: 12 Jun 2011
  • Loc: Texas Hill Country

Posted 26 June 2019 - 11:44 AM

John, the button on the right side of the blue LED display actually kills the backlight.

 

No need to "red tape" it.  :)  



#8 jdupton

jdupton

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1719
  • Joined: 21 Nov 2010
  • Loc: Central Texas, USA

Posted 26 June 2019 - 11:52 AM

Mike,

 

That's a nice looking project! I'm still trying to figure out what's what in the photo.

 

Is the LiFePO4 battery in the lid or is that the BMS? But there's a key switch and a bunch of meters in the lid too. Hmm.

 

And what are the six black barrel things across the back? Are those your output sockets? There is one on each side and two in the front also.

 

Wait! Do I have everything backwards? The lid is lying in the front of the picture? That would make more sense. Some of those black barrels are meters then. I'm still guessing the 6 along the back are outputs.

 

Are you going to do a write up of the build? It's definitely an impressive build!

 

   I think you have it right now. The last photo in the original post showed the battery box opened up as if it were hinged at the back where the deep battery well at the rear of the photo is the bottom of a standard Group 27 battery box as used for RVs or fishing boats. So, the top half of the photo is the main battery case with the battery sitting inside. The lower portion of the photo showed the lid opened up (as if hinged) and laying open to see the internals. The barrel shaped objects seen protruding into the lid are a mixture of 12 volt outlets, meters, USB charger outlets and switches all made for automotive / marine use.

 

   Here are some photos of the parts laid out before any of the wiring was added. It helps to clarify what everything is in the wired photo above. (I did change the side for the battery monitor LCD unit but otherwise, the layout is close to the final implementation.)

 

IMG_0020_20190612.jpg

Photo of inverted lid to battery box showing parts layout.

 

   The bottom of this photo is the front of the box. From left to right across the lower edge of the photo is: Voltage / Current Meter, Power Switch, Keyed Master Power Switch, Power Switch, and Voltage / Current Meter.

 

   The top of this photo is the back of the box with two sets of three regulated power outlets.

 

   The left and right sides in the photo each show the USB chargers (shorter barrel on incline) and the non-regulated high current power outlet.

 

   Along the center-line of the lid are two fuse distribution blocks for the two different regulated output voltages. These are wired to the regulator modules and then to the power outlets on the back.

 

   The red electronics modules are the synchronous DC-to-DC converter / regulator units.

 

   The black module with white label is the battery power monitor LCD unit.

 

 

IMG_0028_20190612.jpg

Photo of the Outside Front of the power box lid.

 

 

IMG_0033_20190612.jpg

Photo of one Outside Side of the power box lid.

 

 

IMG_0032_20190612.jpg

Photo of the Outside Back of the power box lid.

 

 

John


  • psandelle and BHPR like this

#9 jdupton

jdupton

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1719
  • Joined: 21 Nov 2010
  • Loc: Central Texas, USA

Posted 26 June 2019 - 12:07 PM

James,

 

That's a really nice setup, but you forgot an important detail, the approximate cost.

 

[snip]

 

Oh, in terms of cost, I recall that each battery was about $100 (34AHr, sealed AGM, deep cycle), the PowerPower junction box was $58, the battery boxes (3) where each about $10, the voltage regulators were about $20 each (sealed, weather proof, about 60W each), and then there was wire, extra fuses, and some terminals and connectors for the batteries and some other hardware and that could have been about $100. The multi-meter (which also does a running accumulation of WHrs) was $15.

 

So, total (gulp) was $543 (plus tax). It took me over one year to get this all together (not purchased at the same time) and as an extra I also purchased a nice A/C inverter which I can also use during power outages at home. I don't plan on using the inverter in the field, unless I get something that requires an odd power input.

 

   Thanks for the comments. As Mike pointed out above, you probably don't really want to know the cost. I don't have exact figures at hand but you can purchase a grab-and-go mount for less. tongue2.gif

 

   The BattleBorn battery was about $950, the synchronous regulators were about $35 each, the USB chargers cost about the same as the voltage / current monitors at about $18 each, the battery monitor LCD also about $18, the outlets were about $6 each, and there is probably another $100 to $125 in fuses, wiring, connectors and other stuff in there.

 

   My older ten year old box cost me almost $500 when I built it. The Optima deep cycle marine batteries are now about $275 so I considered the LiFePO4 be nearly on par in terms of cost of a high quality battery given that it also has more than 3X the capacity of the old Spiral AGM Optima.

 

   This new box is much lighter and should serve me until I am too old to image with my current set-up. I hope to get 10 to 15 years of life out of it.

 

 

John



#10 calypsob

calypsob

    Aurora

  • *****
  • Posts: 4611
  • Joined: 20 Apr 2013

Posted 26 June 2019 - 12:08 PM

Wow makes mine look so simple lol. Fantastic work!



#11 jdupton

jdupton

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1719
  • Joined: 21 Nov 2010
  • Loc: Central Texas, USA

Posted 26 June 2019 - 12:11 PM

Eric,

 

John, the button on the right side of the blue LED display actually kills the backlight.

 

No need to "red tape" it.  smile.gif

 

   Yes, the LCD will normally be kept off. The red tape will be used to make sure when it comes on in alarm mode, it will not be too distracting. You see, I have set a battery alarm to notify me when the battery is getting low. When that alarm triggers, the LCD flashes on and off to let you know. At a public star party I wouldn't want the alarm to break the "red light only" rules. So, it will be easiest to just mask it red from the beginning.

 

 

john


  • epdreher likes this

#12 kisstek

kisstek

    Ranger 4

  • *****
  • Posts: 312
  • Joined: 25 Jul 2018

Posted 26 June 2019 - 12:12 PM

Ah! Very informative photos. Thanks!!!

 

One more silly question: how do you attach the DC converters and the fuse panels to the lid? I don't see any screws thru the battery box.

 

I have an old tech marine battery in one of those battery boxes. My meters and the power switch wouldn't fit in the box with the battery so they're all dangling outside on the wires. Not ideal! And mine weighs a "three tons"! Or so it seems when carry the thing across the field and the handles on the battery box are digging into your hands.

 

You've done a really nice job making it all look very finished and professional!



#13 scadvice

scadvice

    Apollo

  • *****
  • Vendors
  • Posts: 1147
  • Joined: 20 Feb 2018
  • Loc: Lodi, California

Posted 26 June 2019 - 12:20 PM

I can see it now at the local star party...it's...3am... " Uhhh Hi John, my battery just died. Do you have an extra port I can plug into?" uhhh5.gif


  • Bob4BVM and BHPR like this

#14 jdupton

jdupton

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1719
  • Joined: 21 Nov 2010
  • Loc: Central Texas, USA

Posted 26 June 2019 - 12:25 PM

Mike,

 

One more silly question: how do you attach the DC converters and the fuse panels to the lid? I don't see any screws thru the battery box.

 

   I balked at using screws to attach the internal components. Instead, I used a combination of "3M Super Strong Double Sided Tape" for the ground junction and fuse holders. For the regulators, I use a strong version of Velcrow-like feet. That way, there is some air circulation under the modules and they can be removed if one fails in the future. The wiring is so stiff if the Velcro were to ever fail, the modules wouldn't move more than 1/16" or so. When I wired them in, I used the stiff wire with strategic bends to help keep them in place.

 

 

John



#15 elmiko

elmiko

    Mercury-Atlas

  • -----
  • Posts: 2713
  • Joined: 27 Jul 2009
  • Loc: Arizona

Posted 26 June 2019 - 12:34 PM

Really nicely done  John. I did something similar.  Just not quite as elaborate. I used  two different battery cases.  Each with 100amp hour battery. Marine deep cycle.

I use one for my laptop and one for all my rig.



#16 james7ca

james7ca

    Fly Me to the Moon

  • *****
  • Posts: 7013
  • Joined: 21 May 2011
  • Loc: San Diego, CA

Posted 26 June 2019 - 12:37 PM

James,

 

 

   Thanks for the comments. As Mike pointed out above, you probably don't really want to know the cost. I don't have exact figures at hand but you can purchase a grab-and-go mount for less. tongue2.gif

 

   The BattleBorn battery was about $950, the synchronous regulators were about $35 each, the USB chargers cost about the same as the voltage / current monitors at about $18 each, the battery monitor LCD also about $18, the outlets were about $6 each, and there is probably another $100 to $125 in fuses, wiring, connectors and other stuff in there.

 

   My older ten year old box cost me almost $500 when I built it. The Optima deep cycle marine batteries are now about $275 so I considered the LiFePO4 be nearly on par in terms of cost of a high quality battery given that it also has more than 3X the capacity of the old Spiral AGM Optima.

 

   This new box is much lighter and should serve me until I am too old to image with my current set-up. I hope to get 10 to 15 years of life out of it.

 

 

John

Okay, then it looks like you spent just over twice as much as I did, but you also have twice the total capacity and a few extra features (I don't have any USB power outlets). I also have some more backup devices (like an extra set of regulators) and I have a very small 14AHr AGM deep-cycle that can be used to power a small mount. But, none of that was included in my stated price.

 

I get my half capacity from using 3 x 35AHr = 105AHr / 2 ≈ 50AHr usable.



#17 BHPR

BHPR

    Lift Off

  • -----
  • Posts: 24
  • Joined: 14 Aug 2017
  • Loc: Maryland

Posted 27 June 2019 - 07:36 AM

New battery box project.jpg

 

 

New battery box project.jpg]I wish I had yours to review a few weeks ago. Just working on a 50AH Renogy Lifep04 battery box. I love the way you did yours. I did not consider a box like that. I tried an ammo box and it was just too tight. Using a Craftsman toolbox. My only hangup right now is sorting out how to wire up the Thornwave Power monitor so I get the solar input and the loads through the wiring. I have 2 Renogy flex 50w panels for 100w solar charging. Will post a pic when I get one. It's not ready for prime time yet:) Your build is so cool smile.gif

 

Okay snapped a pic. Battery will sit on piece of wood. I needed something to hold a strap to help stabilize the battery. Solar input on right. Still have some wiring to sort through.... Not as pretty as yours though.... it really is nice:)


Edited by BHPR, 27 June 2019 - 05:39 PM.

  • psandelle, elmiko and jdupton like this

#18 Bob4BVM

Bob4BVM

    Surveyor 1

  • *****
  • Posts: 1867
  • Joined: 23 Mar 2015
  • Loc: W. Oregon

Posted 27 June 2019 - 01:51 PM

Very clean build there John !   I can appreciate the planning & attention to ergo details that went into this.

 

BTW, isn't it amazing how many wire connections it takes to do something as relatively simple as this ?  I swear, no matter how small my electronics projects are, it seems the wires just multiply by the time the thing is all together ! 

 

CS

Bob


  • jdupton and BHPR like this

#19 jdupton

jdupton

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1719
  • Joined: 21 Nov 2010
  • Loc: Central Texas, USA

Posted 27 June 2019 - 08:16 PM

BHPR,

 

New battery box project.jpg]I wish I had yours to review a few weeks ago. Just working on a 50AH Renogy Lifep04 battery box. I love the way you did yours. I did not consider a box like that. I tried an ammo box and it was just too tight. Using a Craftsman toolbox. My only hangup right now is sorting out how to wire up the Thornwave Power monitor so I get the solar input and the loads through the wiring. I have 2 Renogy flex 50w panels for 100w solar charging. Will post a pic when I get one. It's not ready for prime time yet:) Your build is so cool smile.gif

 

Okay snapped a pic. Battery will sit on piece of wood. I needed something to hold a strap to help stabilize the battery. Solar input on right. Still have some wiring to sort through.... Not as pretty as yours though.... it really is nice:)

 

   That is going to work well. The Renology batteries have a great reputation. Your box should easily last for a very long time. I toyed with the idea of having a solar charging input on my design but that would require more wiring and taking the panels with me. I opted for extra capacity instead. Let us know how well the solar charging system works with yours.

 

   Regarding stabilizing the battery more, I used sheets of 1/2" thick dense blue "camping pad" foam as sold at Walmart and sporting goods stores. I simply cut sheets to wedge into place along three sides of the battery to keep it from shifting around in the box. you might be able to use a combination of a plywood cage and camping foam to keep the battery in place. The wiring is always trouble when working with larger gauge wire on a project like this. Good luck with that aspect.

 

 

John


Edited by jdupton, 27 June 2019 - 08:37 PM.

  • BHPR likes this

#20 jdupton

jdupton

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1719
  • Joined: 21 Nov 2010
  • Loc: Central Texas, USA

Posted 27 June 2019 - 08:32 PM

Bob,

 

Very clean build there John !   I can appreciate the planning & attention to ergo details that went into this.

 

BTW, isn't it amazing how many wire connections it takes to do something as relatively simple as this ?  I swear, no matter how small my electronics projects are, it seems the wires just multiply by the time the thing is all together ! 

 

   You said it! Doing the wiring on mine was like a wrestling a bear. I did not mention it before but I attempted wiring three times before making it work. The fourth attempt was the charm.

 

   I knew it would be tight after laying out the components but the extra length of the crimped on terminal connectors combined with very stiff wire kept eating my lunch and kept me from fitting the DC-to-DC regulators into the box. I ended up cheating -- I trimmed some of the connectors back as short as I could and then instead of daisy-chaining the common wiring, I soldered "Tee" connections into a bus wire. The shortened connectors combined with stiff wire left some very small exposed bared wire areas at many of the connectors. After getting the wiring harnesses built, I "painted" all the little bare spots next to the connectors with liquid rubber (PlastiDip for tools) for extra insulation.

 

   The wiring (and multiple rewiring attempts) took much longer than punching the holes for all the external power outlets, meters and switches. For this, I drilled carefully placed pilot holes and then used a Greenlee chassis punch to complete the sized hole. I was worried about getting the holes nice and round and clean but the chassis punch made it one of the easiest aspects of the build. The rectangular opening for the Battery Monitor was cut by making a temporary "fence" around the hole location and then using a RotoZip tool to route out the hole. That was pretty easy also compared to the wiring.

 

   Thanks for the comments...

 

 

John


  • BHPR likes this

#21 jdupton

jdupton

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1719
  • Joined: 21 Nov 2010
  • Loc: Central Texas, USA

Posted 27 June 2019 - 09:05 PM

   As a follow-up on the testing of the box, here is what I have found. The cooling of the DC-to-DC modules is not going to be a problem.

 

   I ran two tests yesterday evening and last night. I connected up my laptop to one of the regulated voltage outputs and ran it in different modes while monitoring the temperature of the heat sink on one of the regulator modules as well as ambient room temperature. I only drew up to a hair more than 5 Amps from the regulator module but by varying the laptop load (through a high efficiency pure sine wave inverter), I found that the temperature of the heat sink increased a little more than 1.25° C per Amp of regulated load current. The modules are rated to an 8 Amp load or 100 Watts total dissipation before shutting down. That would seem to limit my temperature rise to no more than 12° C at full load, worse case. I think the modules are completely safe in that temperature range. The fans I mounted on the modules are doing the trick.

 

   After testing temperature loading last night, I ran a camera test to gather a new set of Library Frames at a new gain. The sequence ran for 8 hours with my ASI294MC-Pro, DIY Flat Light Box, and Lenovo P51 Laptop / Mobil Workstation (in my custom Imaging Power Mode) all on the 13.3 volt regulator side. The total usage from the battery over the 8 hours was 188 Watt-Hours. (The Field Power Box has a total nominal capacity of 1,200 Watt-Hours.)

 

   In real field usage, I will have the additional loads of the guide camera, my HDX110EQG mount, a Moonlight Focus controller and drive, a USB over Cat-5e controller, and Tempest Fans. That may roughly double the total load but will normally be split between the two regulated halves of the box with the laptop on one of the high current outlets on the battery rather through a regulator. I hope to get a couple of days of clear weather to set this all up outside and get a detailed measurement of usage over a night of imaging. At the moment, I think my estimate of three imaging nights at a remote site will be conservative.

 

   Thanks again for all the kind comments on this project.

 

 

John


  • BHPR likes this


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





Also tagged with one or more of these keywords: accessories, astrophotography



Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics