4 replies to this topic

[Lardo5150]

Going to need a power station for a few times throughout the year.

It will not be running all night, but need it to power the following for several hours.

Laptop

CGEM II Mount (C925)

Celestron Autoguider

HomeBrew Gen3 with GPS

 

Very new to Power Stations, and there are a lot of options out there, but they want all the money from my wallet.

So looking for recs from the experts on one that I can run the above for several hours.

 

If you can advise me at least on what the minimum specs should be on it, I can go looking for a sale or something.

[DeepSky Di]

Make sure it's LiFePO4 - if it is it will say so; if it isn't it will say Lithium ion etc. LiFePO4 lasts longer and is safer.

 

Power station capacity is measured in watt-hours (Wh). Watts are volts x amps. So 12V 3 amps = 36watts, 360 Wh would runn for 10 hours. I have an approx 500Wh Bluetti which can run 2 rigs for a night.  

 

Then make sure it has DC 12V 5.5mm sockets as well as a car port, 120V for the laptop charger and  USB A and USB C for mobile devices. Bluetti stopped doing the 5.5mm sockets unfortunately,

 

There are many here who make their own power stations from parts; it's an option for people who are comfortable doing this, but it may not necessarily cost much less once all the parts are added up.

[Phil Sherman]

If you're planning on running a laptop from a field use battery then it's critical to purchase a DC power supply for the laptop. If you don't do this, you'll be stuck using a 12VDC to 120VAC inverter, something built into most of the commercial power stations. After this conversion, you'll be using the laptop's AC power supply to convert the 120VAC to the correct DC voltage to power the laptop. This double conversion consumes power and provides no benefit to how long the device will run your gear. 

 

Some laptops (I know this includes DELL) require a power supply that can communicate with the laptop before the laptop will accept power from the power supply. When you purchase a DC power supply for one of these laptops be sure to verify that its specifications include powering your particular model laptop. 

 

When computing your power requirements, add up the power consumed in watts by all of the devices you intend to power. Don't forget that AC power supplies frequently will supply much more power than the attached device requires. Mounts are the perfect example of this. A mount draws maximum power when slewing on both axes at the same time. When it's tracking, it can easily draw less than 1/3 that amount of power. Even when slewing, most amateur level mounts draw significantly less power than the AC supply can provide. Dew strips draw power only when active which, depending on your power setting to them may be only 50% of the time. 

 

However you calculate your power requirements, add at least 10% for voltage conversion losses and you'll have the minimum amount of power you'll need for a single hour of field use. Multiply this by the number of hours you expect your session to last and you'll have a minimum watt-hour requirement for the power supply.  I'd strongly recommend obtaining a power supply that provides at least 150% of your expected session requirement. This should also provide you with enough reserve capacity to cover cold weather usage when battery performance degrades and headroom if you obtain additional gear or your session runs longer than you expected.

[JimTheEngineer]

The laptop will be extremely power hungry. Next would be dew heaters which you have not listed. I suggest you set up everything outside with only one power input and get a cheap power meter on Amazon and run a session all night. Then add maybe 50% safety margin.

The sweet spot on costs per Wh are power stations in 1000Wh size. I wouldn’t get anything less than 500Wh. Pay attention to the exact voltage output of what you are buying. You want nothing less than 13vdc. The 2 power stations I have purchased were EcoFlow and BLUETTI. EcoFlow River Max 2 voltage is NOT high enough (my big mistake). BLUETTI AC200Max voltage is good. Install just any Amazon or cheap cables running from an EcoFlow low voltage and you will be chasing “bugs” in Astro equipment because voltage at the end of the cable and cheap connectors will result in intermittent low voltage issues.

Run everything straight from DC cables. Power usage will be increased 30% if you convert dc battery to ac then back to dc with those power adapters.

Edited by JimTheEngineer, 22 June 2025 - 09:11 PM.

[TelescopeGreg]

What the others said.

 

I would add that the laptop "DC power supply" mentioned above is often called a car or travel laptop adapter; 12v "accessory plug" (aka "cigarette outlet") on one end, and the laptop-appropriate plug on the other.  It's much more efficient than using the regular "wall wart" that the laptop comes with.

 

Two other thoughts.  First be sure that the laptop is fully charged at home before taking it out for imaging.  No point recharging the internal battery from your external one.  All you are doing is moving juice from one battery to the other, losing about 15% of it in the process.

 

Second, in choosing an appropriate laptop remember that you do not need much processing power to run your system.  Leave the gaming laptop at home, and use a small laptop or even an old "netbook".  If it's designed to run for many hours on its own, don't even bother to hook it to the system battery.

 

My own system includes the mount, a pair of cameras (one with a cooler), Raspberry Pi 4B to do the real-time guiding and image taking, and a hand-me-down 14" laptop that acts as the Raspberry Pi's remote keyboard / mouse / display.  There's also a pair of dew heaters, and in winter even a heated travel blanket (for me!).  I can run the whole lot for 3-4 hours on a 10 amp-hour 12v LiFePO4 battery and still have some charge left over.

 

Oh, one last note...  It's easy to forget, now that we're in summer, that battery capacity drops when they get cold.  So be sure to build in enough margin (perhaps 2x) for when the system needs to be out in the cold.  And if "cold" includes "below freezing", seriously consider some sort of insulated container (e.g. ice chest) to put it in, and remember that it is not possible to charge a Lithium battery if it's below freezing.

Edited by TelescopeGreg, 23 June 2025 - 09:32 PM.