Check your battery type and its capacity
Deep Cycle Batteries
When opting for a battery as your power source, it is advisable to select a “deep cycle battery.” These batteries are specifically engineered to endure regular and substantial discharge, utilizing most of their capacity without incurring damage or compromising their longevity.
A typical AGM deep cycle battery
Car Lead Acid batteries are not well-suited for astrophotography applications. These batteries are engineered for short bursts of high current, primarily for engine ignition. Using them for prolonged periods, especially when the battery’s charge level falls below 50%, can lead to significant capacity degradation and eventual failure. Car batteries are not designed to sustain continuous power supply over extended durations, making them an unsuitable choice for powering your astro-setup.
There is also the option of the new LiFePo batteries but there are lots of constrains here.
One of the primary advantages of LiFePo batteries is their lightweight and compact size when compared to traditional AGM deep cycle batteries. Additionally, LiFePO4 batteries offer a remarkable shelf life of up to 10 years without recharging, far surpassing the 3-year shelf life of Lithium-Ion batteries and the 6-9 months of Sealed Lead-Acid batteries. However, it’s important to note that the major drawback of these batteries is their considerably high price point. A 50AH LiFePO4 battery can cost approximately $450 to $500, significantly more expensive than an equivalently sized deep cycle battery, which typically ranges from $80 to $100.
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
Below is a general description of a typical astrophotographic setup involving a 4-inch refractor telescope, along with a rough analysis of its power consumption:
Telescope and Mount: The 4-inch refractor telescope and equatorial mount typically consume a modest amount of power, usually within the range of 1-2 amps.
Camera: Astrophotography cameras can vary significantly in power consumption, but a rough estimate for a cooled camera might be around 2-3 amps, depending on the cooling system and exposure settings.
Accessories: Power requirements for accessories like guiding scopes, autoguiders, dew heaters, and filter wheels can add an additional 1-2 amps, depending on the specific equipment and usage.
Laptop/Control Computer: The laptop or control computer used for camera and mount control typically draws a few amps.
Overall Total: In total, a typical astrophotographic setup like this might require approximately 6-8 amps of current at 12 volts, depending on the specific equipment and usage.
It’s essential to calculate the actual power consumption of your setup based on the specifications of your individual components and how you plan to use them. Additionally, consider the capacity and runtime of your power source, whether it’s a battery or an external power supply, to ensure uninterrupted imaging sessions.
Your best case scenario:
|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”)
|Guiding Camera / USB Hub / Focus Motor / etc
|Small Factor PC (E.g Intel NUC i3)
In the best-case scenario where your LiFePO4 battery has a capacity of 12Ah and your equipment consumes 6.3 amps, you can expect the battery to power your equipment for approximately 1.9 hours. This calculation provides an estimate of the continuous runtime before the battery is fully depleted. However, actual battery performance may vary based on factors such as the battery’s state of charge, temperature, and discharge rate. It’s essential to monitor your battery’s status during operation and have a backup power plan in place for longer astrophotography sessions.
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 up to 3 nights