Off-Grid Astronomy: A Guide to planning power


Embarking on off-grid expeditions under the pristine night sky is an essential experience for every astrophotographer. As someone who frequently engages in such ventures, this series aims to empower you with the insights required for a successful astronomical journey.


1. Power Requirements:

Efficient power management is crucial, and direct current (DC) stands as the optimal choice for off-grid operations. Transitioning from alternating current (AC) to DC incurs efficiency losses, impacting running time. The key is to transition all equipment to DC power, eliminating reliance on AC power packs.


2. Voltage Considerations:

Understanding voltage requirements is imperative. Different devices have varying optimal voltage ranges. For instance, EQ6 Pro/R operates at 12V with a range of 12V-14V, while EQ8 Pro prefers 15V. Thoroughly review equipment specifications to determine their optimal voltage.


3. Current Analysis:

Current, measured in amps, represents the total volume of electricity flowing through a device. Accurate measurement is crucial, considering the maximum values listed on power packs. For instance, EQ6/8 mounts typically operate around 1 amp per hour, while QHY/ZWO cameras draw 2-5 amps per hour. Understanding both Total Engineered and Total Measured currents is essential.


4. Battery Selection:

Choosing the right storage system is pivotal. The two primary options are Lead Acid and Lithium batteries. Lead Acid is cost-effective but has drawbacks such as weight and temperature sensitivity, while Lithium is lightweight, temperature-resistant, and boasts a longer lifespan. Consider your budget and preferences when making this choice.


This comprehensive guide provides a foundation for selecting the appropriate batteries for off-grid astrophotography, emphasizing the superior capabilities of Lithium power sources. As costs decrease, Lithium options are becoming more accessible, promising enhanced reliability for extended astronomical endeavours.

Stay tuned for the upcoming segment on effective battery charging strategies, whether in the field or at home.

Worked Example:

Providing a detailed example, we consider a 10-hour imaging session with various equipment. Calculations for both Lead Acid and Lithium batteries are presented, illustrating the advantages of Lithium in terms of capacity, weight, and efficiency.


Assume the following:

Total imaging session – 10hrs
Nominal voltage – 12 volts
Lowest temperature – 10 deg C

    1. NUC – 2 amps supplied at 19 volts
    2. EQ8 – 5 amps supplied at 12 volts
    3. QHY600 – 5 amps supplied at 12 volts
    4. Sundry equipment – 2 amps supplied at 12 volts
    5. No dew heaters operational

1. I have measured the total draw at 3.6 Amps
2. I have summed up the design Amp requirements to 14 Amps

For simplicity I will convert the required power to be provided for a Lead Acid:

Current x Voltage = Watts

3.6 amps X 12 volts = 43.2 watts

I will be running the system for 10 hours as mentioned above:

10hrs x 43.2 watts = 432 watts

Now I need to pick a capacity that works

Lead Acid:
432 watts / 12 volts = 36 amps

36 amps X 1.1 = 39.6 amps
(increase of used capacity for temperature Reduction in capacity due to temperature (approximate guess) 10%)

39.6 amps X 2 = 79.2 amps
(allowing for 50% lead acid depth of discharge)

Let us give a small buffer in case something is slightly different on the day of say 20%
79.2 amps x 1.2 = 95.04 amps

Selected lead acid battery would be 100 amp-hour.


Everything is the same for a Lithium battery up until we start allowing depth of discharge etc.

432 watts / 12 volts = 36 amps

36 amps / 0.8  = 45 amps
(allowing for 80% lithium depth of discharge)

Let’s give a small buffer in case something is slightly different on the day of say 20%
45 amps x 1.2 = 54 amps

Selected Lithium battery would be 60 amp-hour or maintain a 100 amp – hour battery and run for multiple nights!

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