Cable management recommendations for an astrophotography setup
Use a certified and branded power supply unit that can deliver at least 12V DC / 10A.
The higher the delivered Amps, the better. A 20$, cheap 12V/10A PSU will probably have power issues resulting noise, less power than was advertised and high voltage ripple. You always get what you pay for.
You can check our certified power supply units
Make a rough calculation of your average current consumption. PSUs tend to overheat when they are close to their max power output. Therefore, use a PSU that will be able to deliver power at least 30% higher than this consumption. If you consume 7A, get a 10A PSU.
Use thick and short power cables
Use at least a AWG17 input cable which can deliver at max 10Amps. For your devices make sure you use AWG20 or thicker cable which can deliver up to 5Amps. Thin and long cables are going to produce a severe voltage drop during power load (voltage lower than 11.5 Volts) leading to multiple problems such as:
- Mount stall – Mount motors (RA /DEC) cannot receive the required power, resulting to mount slewing or tracking failures (motor might jam producing noises).
- Camera issues – Lots of CCD /CMOS cameras might produce artifacts (band lines, patterned or random noise) in light and dark frames if input voltage is below 12.0 Volts. These artifacts can be also produced if output quality of the PSU is bad. Moreover, cooling TEC might not be able to achieve the maximum delta temperature.
- Small factor PC unexpected resets – If you use an Intel NUC or a similar small factor PC which is powered with 12Volts you might see random power resets / reboots especially when the CPU requires high power to perform heavy tasks.
If you use AC power and convert it to 12V DC, it is highly recommended, to bring the AC mains cord close to your pier / mount head and then use the PSU to transform mains voltage to 12V DC.
AC voltage can travel at long distances. DC has voltage drops when it travels at long distances especially through thin wires.
Same applies to batteries. Place the battery as close as possible to your setup. It is a non-sense to have the battery away from your setup and use long wires to transfer the power there. By doing that you re loosing significant amounts of power and you are prone to voltage drop
Pay extra attention to the battery adapters
There are lots of recorded cases that these adapters (image below) have very poor wiring inside. Usually the cables are very thin leading to severe voltage drops.
Make sure that the adapter does not create a power bottleneck between your battery and your equipment. Cables should be thick enough to support up to 10Amps of current.
(We have seen that they are advertised that they are up to 15A but usually they can deliver up to 5-6Amps at max)
Check your battery type and its capacity
Deep Cycle Batteries
If you are going to use a battery, get a “deep cycle battery” that is designed to be regularly deeply discharged using most of its capacity.
A typical AGM deep cycle battery
Car Lead Acid car batteries are not appropriate for astrophotography usage. If a car battery reaches below 50%, the battery will start losing, gradually, its full capacity and eventually die. Car batteries have been designed to produce high current at short times suitable for engine ignition. They are not designed to provide power for long hours to your astro-setup.
There is also the option of the new LiFePo batteries but there are lots of constrains here.
Their biggest advatange is the low weight and size compared to a classic AGM deep cycle battery. Also LiFePO4 has an un-recharged shelf life of 10 years compared to 3 years for the Lithium Ion and 6-9 months for a Sealed Lead-Acid battery. The con is their very high price: A 50AH battery costs arround 450-500 USD compared to a same capacity deep cycle battery which costs 80-100 USD).
Most portable LiFePo powertanks have a 160Wh capacity. This means 160Wh / 12V = about 13AH (Amp/hours).
Please note that this capacity is very low for a standar astrophotography setup
Here is a typical astrophotographic setup (4” refractor) and a rough analysis of the current that it consumes:
|Cooled CMOS/CCD Camera||2.5 Amps (cooling power to 80%)|
|Equatorial Mount (e.g EQ6R-Pro)||1 Amp (during tracking)|
|1 x Dew Heater (4”)||1 Amp|
|Guiding Camera / USB Hub / Focus Motor / etc||0.3A (average)|
|Small Factor PC (E.g Intel NUC i3)||1.5A (average)|
If your LiFePo batery (like the image below) has a 12Ah capacity then -> 12Ah / 6.3 Amps = 1.9 hours (this is the best case scenario that your LiFePo battery will provide the required juice to your equipment) *
A LiFePo4 battery with 159Wh means 159W / 13Volts = 12Amp/hours – Usually these batteries are only suitable to power on an eq mount and nothing else.
* For a 6h astrophotography session) you will need ar least a 6.3 * 6 = 38AH battery
* You usually need a larger capacity battery as battery should not have been entirely drained out!
A 100AH deep cycle battery can easily provide the power you need for 2-3 nights
LiFePo4 power stations
These new power stations contain a large stack of LiFePo4 batteries. They have lots of advantages compared to classic Lead Acid (Car) Batteries. such as longer life span, no maintenance, extremely safe, lightweight, improved discharge and charge efficiency.
The main disadvantage is that they are still very expensive. A 500Wh capacity power tank costs arround 500 USD.
They usually deliver 13Volts and they have the ability get recharged when you simultaneously power your equipment.
A power station like the one at photo below can also be used as a uninterruptible power supply (UPS) if you use an outdoor fuel generator or any other power source. A nice power backup to avoid power disruptions.
A 500Wh (Watt/Hours) means that device has a capacity of 500 / 13V = 41 Amp/hours. Based on the above table for an typical astrophotographic setup consumption, this battery tank can power up your equipment for about 6 hours (if your consumption is close to 6Amps). Yes, we hear you, the 6hours time seems to short but… this is what you get with these tanks. A power tank that can compete with old heavy lead acid batteries costs up to 2500$ for sure!
Separate power from USB cables
Always place USB cables away from the power cables. It is preferable to route them inside two different strip lanes. If you use Velcro strips or cable management “rails” better tie all USB cables together and all power cables together on a straight line (do not loop them to reduce the length). An alternative option is to use good quality / shielded USB cables.
Pay attention to USB maximum cable length
USB 2.0 devices require a maximum cable length of 5m/ 16 ft and USB3 can go up to 3m / 10ft. Practically you should use shorter cables. Never reach the maximum cable length limit. USB random disconnects or USB devices that will not be able to connect (randomly) to your PC is a bad effect of this approach.
Humidity in combination with low temperatures gradually affect the quality of your USB cables. There are numerous reports that long USB cables were working fine at the beginning but after 3 months, on a very humid place, devices were having random USB connectivity disconnects or USB packet losses.
USB3 protocol is way more “difficult” than the USB2 as it has higher bandwidth, provides higher transfer speeds and requires better quality cables and technical knowledge on designing reliable and certified USB3 devices.
Avoid using internal USB Hub of Cmos cameras
Lets set this straight. The USB Hub implementation on those cameras is a very bad design with multiple flaws violating USB-IF Compliance.
The most important flaw is that most of these cmos cameras have a non-powered dual port USB hub.
If you use a 3meter USB3 cable to the main camera and a 2m USB cable to your guiding camera, the total length is 5meters (16ft). As the camera’s Hub isn’t a powered one, the USB communication will have severe issues and probably random disconnects (most of times you will not be able to discover the guiding camera at all!). There are two solutions here: a) either use short USB cables as possible b) invest on a good USB hub and do not use this dual USB Hub at all!
Avoid using 2.4GHz WIFI along with USB3 devices.
USB 3.0, or SuperSpeed USB, uses broadband signaling that can interfere with cellular and 2.4GHz WIFI or bluetooth signaling. This interference can significantly degrade cellular, bluetooth and 2.4GHz WIFI performance. For detailed information please check Intel’s whitepaper
Lots of USB 3 devices generate radio interference in the 2.4GHz frequency, and this can have an adverse effect on both Wi-Fi and Bluetooth as they operate on this frequency. Therefore, It is strongly advised to disable WiFi at 2.4GHz and use only WiFi at 5 GHz only (802.11a).
USB Extenders can be used but with extra caution
USB extenders have lots of incompatibilities between USB Hubs and cables. We do not recommend USB extenders but if you do so, make sure that you are going to choose a known branded USB active extender. You always get what you pay for.
Invest on an industrial powered USB2 or USB3 Hub
All USB commercial hubs have an operating temperature range from 0°C to +60°C. This is because all these USB Hubs have been designed to work inside your cosy room and not outside, in the cold!
All of these USB hubs are not designated for astrophotography usage in the harsh winter. The sad truth is that all commercial hubs work out of specifications and most of USB disconnects / failures you might see in the field are a result of this specific issue. For the best stability & performance invest on an industrial HUB that is certified to work under low temperatures.
A decent cable management example can be seen at the image below. Short USB and power cables, no cable loops. Pocket Powerbox Micro does the power distribution. USB Control Hub gathers all USB devices.