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Power supply assistance!

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#1 wargrafix

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Posted 17 February 2019 - 06:39 AM

While people will suggest going with deep cycle batteries and rigging them up, but I am not a great fan of that solution.


Is there a power solution that I can run my atlas pro for at least 8-10 hours reliable?

#2 Kokatha man

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Posted 17 February 2019 - 07:46 AM

If you look at the pik of my C14 on the EQ8 with its new pier in my latest thread in the SS Imaging forum you will see a purple "jumpstarter" unit at the base of the pier.

 

I have a lot of professional experience with both deep cycle & other lead-acid storage batteries from small aH ratings through to 500aH 2-volt units. (10hr/rate)

 

The single most important aspects of long battery life is ensuring you don't run a battery flat & that you recharge them asap once they are used - & also to give a "top-up" charge regularly even when not in use, be it from a specific trickle-charger or normal charger at an appropriate rate of charge...& if it is capable of being topped up with distilled water (much more preferable also imo) then this is a regular maintenance aspect also to check the electrolyte levels.

 

This ensures that they last as long as possible - the van you also see in that pikky has a set of 3 deep storage batteries (3x120ah = 360aH, 20hr/rate) which are now well over 6 years old & going strong due to a good regimen - but interestingly, the purple "jumpstarter" which has only a SLA (sealed lead acid) battery of pretty low capacity (aH) is over 7 years old & it & another identical one which I use for vehicle emergencies are both going strong! 

 

It is described as a "Super Heavy 1900 Amp" unit which is recommended for diesels if you suffer a flat battery, but the actual SLA inside is fairly small in capacity. (I'm unsure exactly its rating...)

 

Point being that this will drive the EQ8 all night as well as the Moonlite focuser & DRO box, although these last 2 items draw neglible current.

 

I'd imagine Trinidad has no dew issues so that wouldn't seem to be a concern... (I don't use dewheaters personally)

 

I am not recommending either the jumpstarter or the big bank I carry in the van - but my purple portable unit would certainly drive your mount all night - & it's 7+ years old & has been used continuously over that time..! wink.gif



#3 bill5wjw

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Posted 17 February 2019 - 08:15 AM

The fact is we can't change the laws of physics. What ever battery solution you go with -bottom line is that you must have sufficient amperage capacity in any given battery to last through the entire imaging session. I make my calculations based on sunset to sunrise  (in December, for example, -so that's roughly 12 hrs of reliable power that I need.) I use a 100 Amp hour battery and that lasts all night. Could I use a battery with less capacity-say 80 Amp hour? Probably. Such a battery might make it through the night, I don't know-I have never actually calculated my actual total amperage needs. But its easy to do.


Edited by bill5wjw, 17 February 2019 - 08:17 AM.

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#4 WadeH237

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Posted 17 February 2019 - 10:48 AM

Is there a power solution that I can run my atlas pro for at least 8-10 hours reliable?

Yes.  It is precisely the solution of which you are not a great fan.

 

The bottom line is that those deep cycle batteries are designed for discharging a small amount of current over a long period of time.  Starter batteries are designed to deliver a large amount of current over a short period of time.

 

For just running your mount, you don't need a 50 lb, 100 amp hour battery.  Your mount will probably draw about 0.5 amps on average while tracking.  If you run it for 10 hours, you'll need to deliver about 5 amp hours of power to the mount.  Lead based batteries don't like to be discharged more than about 50% of their capacity (and it will start to shorten the life considerably if you regularly do so).  So plan on a battery with at least 10 amp hours.

 

I use these 12 amp hour AGM batteries to run my mounts with good success.  They are pretty small in size, under $30, and weigh around 8 lb.

 

There are also solutions based around lithium ion and lithium iron phosphate batteries, but the cost tends to go up pretty quickly once you start adding capacity.

 

Finally, this guidance is just for your mount alone.  If you are going to add cameras, a laptop, dew heaters, etc., then the capacity you need goes up very quickly.  For my imaging setup, I run a pair of 75 amp hour AGM batteries at 50 lb each.  And that is about the minimum I would consider.


Edited by WadeH237, 17 February 2019 - 10:49 AM.

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#5 Luna-tic

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Posted 17 February 2019 - 12:01 PM

Determine first how much power you need to run your mount, plus anything else you might need (dew heaters) for that length of time (8-10 hrs)

 

The Atlas will probably use about 0.75-.0.8 amp while tracking. 10 hrs x 0.8 amp would be 8 amp-hrs. But then you need to account for slewing to a target, and the Atlas will probably vary between 3-4 amps draw every time it slews. Ten objects over ten hours, with 4 amps for say, 15 seconds to slew and center, is about 2.5 minutes of slewing, or another 10 amps, or 0.6 amp-hr. Say another amp-hr. Dew heater, if used for the entire session, would be about 3 amps x 10 hrs, or 30 amp-hrs. Forget this if you know you won't use them.

 

Once you figure about what you'll use, add at least 20% to that, as you can't draw your power source down past 20% remaining capacity, generally, and then add at least another 10% for losses in the system. It all adds up; I base the current use above on my own experience, I use an EQ6R mount, very similar to the Atlas. I've used one of the "car starter" batteries and it works for about 6 hours at most, but once the battery is drawn down to about 50%, you start getting voltage drops during higher current draw like slewing, and the mount doesn't like that; it will even shut down if voltage drops enough.

 

Lead-acid batteries are heavy, but they ere probably the cheapest option for a high capacity battery, and deep cycle batteries are designed for long sessions of continuous current draw. AGM batteries are lighter, but a lot more expensive, and Lithium is lighter, and even more expensive per amp-hr. Lithium lasts longest, generally, but that depends on which type of Lithium battery (Li-ion, Li-polymer,  Li Fe PO4,) you choose. So, figure out how big a battery you need, how far you need to carry it, and how much you want to pay for it.

 

My own system uses a 96 amp-hr. lead-acid deep cycle, but that runs the mount, two cameras, dew heaters and a laptop.


Edited by Luna-tic, 17 February 2019 - 12:06 PM.


#6 wargrafix

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Posted 17 February 2019 - 03:12 PM

Trinidad has a lot of dew issues, but much less in the dry season. Is there a retail power solution? Like the celestron 17ah powerbank

#7 skybsd

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Posted 17 February 2019 - 03:18 PM

Hello, 

Good to hear from you.., 

 

While people will suggest going with deep cycle batteries and rigging them up, but I am not a great fan of that solution.


Is there a power solution that I can run my atlas pro for at least 8-10 hours reliable?

At what location are you interested getting 8-10 hours or power? 

 

For out in the field - as others have already suggested, deep cycle battery delivered power is precisely the solution for that time window of operation when out in the field. For sure there are alternative battery-based options but depending on your draw, for 8-10 hours, you'd definitely be looking at lugging a few of them and needing to interrupt your operation to swap.., 

 

If the location is at (your own) home, then sure, as long as you have (or can run) adequately isolated safe and reliable outdoor power from your mains connection, then its certainly an option - which is what most folks who operate from their own properties do.., 

 

Hope this helps., 

 

Best.., 

 

skybsd



#8 Rovert9988

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Posted 17 February 2019 - 03:30 PM

I know you aren't a fan, but I'll toss in a vote for the deep cycle solution. I use 2 deep cycle batteries, each about 60-65 Ah for a total of about 120-130 Ah. I've never had power issues, and have manged from 2-4 imaging nights out of a charge depending on conditions. I know they are heavy, but honestly it's not bad to just set them in place and then not worry the rest of the night. They work even in cold (I was imaging in 2 degree F recently), as well as heat (also taken them to deserts). Easy to charge, large capacity, and not too expensive.

 

I also built a little power box for equipment to pair with my batteries. It has a single set of leads going to the battery, and from there has a fuse board going to 3x 12V plugs and 2x 5V USB plugs. I plug in my camera cooler, dew control, USB hub and extension all into it and it closes up to keep everything clean and dry.

 

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Edited by Rovert9988, 17 February 2019 - 03:36 PM.


#9 wargrafix

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Posted 17 February 2019 - 05:11 PM

I am a fan of the capacity, but the building of it is where I am not strongest. This is is out in the field.

Home I have power outlets to work with. This is for outreach. Do any of the astronomy companies have high capacity solutions?
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#10 wargrafix

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Posted 17 February 2019 - 05:11 PM

https://www.amazon.c...NOV6U33XD&psc=1

How about this?

#11 WadeH237

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Posted 17 February 2019 - 05:46 PM

I am a fan of the capacity, but the building of it is where I am not strongest. This is is out in the field.

What do you mean by building?



#12 wargrafix

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Posted 17 February 2019 - 06:06 PM

Assembly of the batteries and power setup. Apologies

#13 WadeH237

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Posted 17 February 2019 - 08:33 PM

If you go with a single battery (like the one that I linked), there is no assembly.  You could use a cable to with large alligator clips to a cigarette lighter style socket.

 

Even if you use multiple batteries, you just connect the positive post of one battery to the positive post of the other battery.  Then you can use the same alligator clips from either of the positive and either of the negative posts, and you get double the capacity available.

 

Some of us go and make custom cables with PowerPole ends and stuff.  And frankly, that is really easy to do if you get a crimper - but it's not strictly necessary.  I've got all of my batteries set up for solar charging, which adds a bit more but is really convenient.


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#14 wargrafix

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Posted 17 February 2019 - 10:32 PM

Ah, ok. Celestron 17ah power tank is any good?

#15 Napp

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Posted 17 February 2019 - 10:39 PM

Ah, ok. Celestron 17ah power tank is any good?

Over priced compared to regular deep cycle batteries.  Also not a lot of capacity.


Edited by Napp, 17 February 2019 - 10:40 PM.


#16 Stelios

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Posted 17 February 2019 - 10:40 PM

Ah, ok. Celestron 17ah power tank is any good?

It's overpriced for what it does, but it will definitely run your Atlas for 10 hours without any issue. (For that matter, the 7AH PT would also work).

 

If you buy one, or any SLA battery, please do yourself a favor and buy a Battery Tender to keep it charged when in the house. You never need to disconnect it. 



#17 wargrafix

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Posted 18 February 2019 - 05:19 AM

Its is pricey, but is anyone retail doing it better and cheaper?

#18 H-Alfa

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Posted 19 February 2019 - 04:10 AM

If you look at the pik of my C14 on the EQ8 with its new pier in my latest thread in the SS Imaging forum you will see a purple "jumpstarter" unit at the base of the pier.

I have a lot of professional experience with both deep cycle & other lead-acid storage batteries from small aH ratings through to 500aH 2-volt units. (10hr/rate)

The single most important aspects of long battery life is ensuring you don't run a battery flat & that you recharge them asap once they are used - & also to give a "top-up" charge regularly even when not in use, be it from a specific trickle-charger or normal charger at an appropriate rate of charge...& if it is capable of being topped up with distilled water (much more preferable also imo) then this is a regular maintenance aspect also to check the electrolyte levels.

This ensures that they last as long as possible - the van you also see in that pikky has a set of 3 deep storage batteries (3x120ah = 360aH, 20hr/rate) which are now well over 6 years old & going strong due to a good regimen - but interestingly, the purple "jumpstarter" which has only a SLA (sealed lead acid) battery of pretty low capacity (aH) is over 7 years old & it & another identical one which I use for vehicle emergencies are both going strong!

It is described as a "Super Heavy 1900 Amp" unit which is recommended for diesels if you suffer a flat battery, but the actual SLA inside is fairly small in capacity. (I'm unsure exactly its rating...)

Point being that this will drive the EQ8 all night as well as the Moonlite focuser & DRO box, although these last 2 items draw neglible current.

I'd imagine Trinidad has no dew issues so that wouldn't seem to be a concern... (I don't use dewheaters personally)

I am not recommending either the jumpstarter or the big bank I carry in the van - but my purple portable unit would certainly drive your mount all night - & it's 7+ years old & has been used continuously over that time..! wink.gif

O

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#19 Luna-tic

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Posted 19 February 2019 - 09:39 PM

I am a fan of the capacity, but the building of it is where I am not strongest. This is is out in the field.
 

Building a DC electrical circuit is pretty basic, for what our needs are. You don't need circuit boards, capacitors, diodes, etc. It's all about routing the power to a bank of outlets that you can connect stuff to. The simplest setup is like what WadeH said above; just a set of alligator clips to the battery terminals with a cigarette lighter socket on the other end. Another, simple, but very effective power system is a Rig Runner panel (Google it). It hooks to the battery the same way, and has a row of connections to hook your gear to, correctly marked for polarity. It was designed for Ham radio operators but lends itself well to our needs, hooking up several DC operated items.

 

More advanced, but still easy to do, is to put a master power switch and main buss fuse in the loop, to help protect your gear. It's all straight-line wiring, and YouTube is your friend. You can even have a DC connector bank, and have an AC inverter connected, for times when you need AC. It can all be in a self-contained box with lifting handles and/or on a small dolly to make it more easily moved about. This is mine; you see the DC Rig Runner outlets in front of the inverter. The battery lies beneath, the top hinges to access the battery for charging or removal, it has straps to lift it, and a dolly to roll it on. The front side has a battery minder that shows voltage, current, watts and amp-hrs. used. It fits nicely under the extended tripod of my mount.

DSC00585 (2).JPG

DSC00591 (2).JPG



#20 gnowellsct

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Posted 21 February 2019 - 05:55 PM

Me:  I dunno Pete my power set up seems pretty crude.  Maybe it's time to fancy it up.

Pete (the electrical engineer for Honeywell HVAC):  Why?  It's cheap, it works, it's reliable, and you've been doing it for almost 20 years.  (and yes that is a picnic cooler for soft drinks/beer)

 

shrug.gif

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  • CN 3 power supply pictures 005.JPG

Edited by gnowellsct, 21 February 2019 - 05:56 PM.

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#21 Mike W

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Posted 21 February 2019 - 11:43 PM

IMG_4765.JPG I have two 12volt 7ah Torquemaster batteries in parallel, each has to be charged separately but not a big deal.



#22 Mike W

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Posted 21 February 2019 - 11:44 PM

2nd photo, BTW there's a car type fuse in there

 

IMG_4766.JPG


Edited by Mike W, 22 February 2019 - 06:03 PM.

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#23 Napp

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Posted 22 February 2019 - 12:00 AM

Here's my DIY power supply.  Four individually fused 12 volt outlets, master on/off switch, voltage indicator and 12 volt deepe cycle marine battery in a marine battery plastic box.  I plan to replace the voltage indicator with a voltmeter/ampmeter.  Not hard to build.   

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  • Battery Box Open.JPG

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#24 Luna-tic

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Posted 22 February 2019 - 10:07 PM

2nd photo, BTW there's a car type fuse in there

 

attachicon.gif IMG_4766.JPG

That looks like mahogany, am I right? Nice power box. 



#25 Luna-tic

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Posted 22 February 2019 - 10:17 PM

Some of us go and make custom cables with PowerPole ends and stuff.  And frankly, that is really easy to do if you get a crimper - but it's not strictly necessary. 

I used a standard crimping tool for my Rig Runner connections (same type connector as the Power Pole). You just have to watch how far the crimped connection spreads, to make sure it will fit the plastic connector body. I also soldered my connections, I guess I'm OCD grin.gif .

 

All this fancy connection stuff is just icing, something to do on rainy days; the simple alligator clamps and cigarette light outlets work just fine. I like the picnic cooler idea above, probably keeps the battery warmer on cold nights, so you don't get the reduced performance that cold weather incurs. I've thought of stuffing pink foam board insulation around mine.




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