Portable Power for the layman

[Dean Hale]

Hello helpful people

My knowledge of electrical power is opening the fridge door and seeing the light come on. I have no additional insight, apart from a healthy fear of blowing my kit up. It's the dark arts as far as i'm concerned.

Reading various post users recommend Talentcell, Tracer batteries, Car batteries and so on. So lots of options. However, i'm also unsure what cables are required especially for the latter and the amount power i would need. I've tried to understand power consumption reading multiple posts on amps, ohms, oohs and arrghs and may as well be reading a mills and boon novel - it's just not sinking in.

I wish to power a CEM26 mount a Beelink mini PC and a ZWO camera, maybe a dew strap or two down the line. Maximum power would be for a few hours a night.

I currently have the Powapacs Atom Pro in my basket £239 + £20 for the cable however wondering if this is overkill and other (ideally cheaper) options are available?

So and with my thanks, would you be willing to share portable power solutions for a similar setup and the required cables. Links to these would be appreciated. 

Thank you

[Clarkey]

I am not an electrical expert but I think you need to clarify a 'few hours' - is this 3 or 8? Big difference. Also, how fussy is the mini pc power requirement? Some are happy with higher voltages but some will not run above 12v.

[raadoo]

I’m as electrically illiterate as they come so my take is that overkill is underrated. Having made sure everything in my kit runs on 12V (most of our bits and bobs do), I basically go for the most amount of amps as I can get. That way I never run out of power mid-session. It also gives me piece of mind that I’m very likely future proofing for any new [power hungry] gear.

[Dean Hale]

9 hours ago, Clarkey said:

I am not an electrical expert but I think you need to clarify a 'few hours' - is this 3 or 8? Big difference. Also, how fussy is the mini pc power requirement? Some are happy with higher voltages but some will not run above 12v.

No more than 3 to 4 hours. For the mini PC it states 12v/2amp so not that power hungry?

[Len1257]

I have a Intel NUC, ASI2600 running at -10C, Dewstraps at 2A, GEM45, focuser, ASI120 guide camera. Run it off a 36Ah LiFePO4 Battery. Lasts long enough for a session. All of above takes 4A max, slewing, imaging the lot. Occasionaly a bit above, most of the time hovering just below. 36Ah / 4A = 9hrs. Seems to last longer than this but thats the maths.

I note that the item you mantioned is rated at 26Ah at 12V so 4hrs or so tops. Do you really need all the extra gizmos that thing has?

I built my own battery case, insulated the battery with foam insulation, fitted a fuse, switch and 12V outlets. There's a thread mentioning a Bison battery case here 

Just add your own battery.

Edited January 16, 2022 by Len1257
Got the maths wrong!

[teoria_del_big_bang]

Power in remote areas is a bit of a mine field, generally doesn't come cheap and even worse if you need differing voltages and not just 12V.

You pretty much have two options, some sort of car or leisure battery or the more modern Lithium ion batteries.
On top of that you can either buy a ready made power pack of various types, some made specifically for astro gear or some for camping or similar pursuits, or build your own.
If you are not that savvy with electrical gear, even 12V then you may prefer the first option.  

Which ever option you pick you need to work out how much power you need (not in volts or amps but in ampere hours) and bear in mind that you will probably not get the amount of power out of any battery that is stated and generally it is not a good idea to run them til they are totally flat anyway (lithium ion not such an issue but the lead acid batteries should not be run till totally flat it will permanently damage them).
So you need to buy a higher capacity than you work out you require and I would recommend getting at least 50% more power.

Working the power out is also a bit of a guessing game but your setup

•  CEM26 mount 0.5A tracking and 0.8A goto, so say average 0.7 A.
•  Beelink mini PC, so take the 2A stated, it probably is less but to be safe.
•  ZWO camera, very much depends on what type and mostly whether it is cooled. a non cooled camera will be maximum 1A but a cooled camera could be up to 4A., but again cooler will not draw maximum current continuously unless in hot climate so again this will be less than the maximum 4A.
•  dew strap or two, again depends on the size of dew strap and how hard they have to work but generally 0.5A to 1A each.

So if camera is cooled you are looking at maximum draw of around  5 to 7 A, if camera does not have cooling then more like 4A.

So to run at 5A for 4 hours you need at least a 20 Ampere/hour source and ideally a bit more to be safe so the one you are looking at at 26 A/h would just about do for 4 hours, and a bit longer if you currently do not have dew straps.

You really do not need the invertor so they may be other things out there  without the inverter a bit cheaper but try to get something with a lithium ion battery, they are lighter to carry and you do not have to be so careful about charging them periodically and running them down. Car batteries can easily be damaged by running them right down and when in storage you need to keep topping the charge up as they will naturally start to run down if left. If these are not well maintained they may still work but the available power will deteriorate and will not deliver the current for as ong as when it was new, sometimes by a lot.

Steve

[Len1257]

I should add that my current draw was measured on an actual current meter and surprised me by being so low. It just confirmed my being able to easily get a full night from my 36Ah battery.

[900SL]

If you are carrying your gear in a car I recommend the Optima blue top 55AH battery. These are AGM leak proof, roll over proof and suitable for marine or astro use, will handle deep cycling and multiple recharges.  I can power my set up for multiple evenings with one.  They have a flat discharge curve for several hours i.e. maintain voltage

Worth mounting in a ventilated box with an inline fuse to a dedicated 12V socket or two.

Also handy for starting the car if you accidentally run the main battery down at night

 

Edited January 17, 2022 by 900SL

[M40]

I must admit that I would be inclined to split the load. It's not something I do, just my thoughts. For the same money I would probably get two of the Skywatcher/Celestron power packs, one for the mount and one for the pc and camera. I suppose it must also come down to how far you are going to carry your stuff as I can see them being quite heavy. The Lithium power packs will be lighter but more expensive.

[Dean Hale]

Many thanks for all of the replies and suggestions and to @teoria_del_big_bang for breaking down the usage, that's really helpful.

@900SL for the Optima blue top 55AH battery sounds great but lost as soon as you mentioned 'inline fuse to a dedicated 12V socket or two'. We have a really helpful astro society here. Luckily work is starting to come back to normal and i should have the time to meet up and ask for advice around this and see similar setups in action.

@M40 i like simple ideas.

In the meantime i've sorted out the garden power. Simply a waterproof box, 10 metre cable and a RCD so portable home wise for hopping around the garden. 

[900SL]

I have the Daddy of that carpet 😜 I'll dig out a photo. 10' X 6' silk Qom by Pirousmand

[900SL]

I do like a good Iranian rug. Or two. Haggling with Mr Kermanshah

 Took 8 weeks of haggling. 

Edited January 17, 2022 by 900SL