Dew heater battery options: Fight the fog!

As an amateur astronomer, there are few things more frustrating than waking up after a long night of unattended astrophotography to find your telescope (or guide scope) lenses covered in dew. It's like the universe is playing a cruel joke on you. You spend hours meticulously setting up your equipment, aligning your telescope, and capturing images of distant galaxies, only to have your efforts thwarted by a thin layer of water. Some areas are more prone to it, but here around the Ozarks there they say, "if you don't like the forecast, stick around, it'll change by this afternoon", we are always on the look out for it.

But dew is an inevitable part of the experience when observing or shooting astrophotography. As the temperature drops, moisture in the air condenses on your telescope's lenses, mirrors, and other optical surfaces. This can lead to blurry images, reduced contrast, and even damage to your expensive equipment. Trust me, I've been there. More times than I'd like to admit, I've woken up to find my telescope looking like it just took a dip in a swimming pool.

How does dew form on my telescope anyway?

Before we dive into the solutions, let's take a moment to understand why dew forms in the first place. Dew is essentially water vapor that condenses into liquid form when it comes into contact with a cooler surface. In the case of your telescope, the lenses and mirrors are often the coolest surfaces around, making them prime targets for dew formation. This is especially true during long nights of unattended astrophotography, when your equipment is left exposed to the elements for hours on end.

Now that we understand the problem, let's talk about the solution: dew heaters. Dew heaters are small, electrically powered devices that wrap around your telescope's optical surfaces and keep them warm enough to prevent dew from forming. They work by gently heating the lenses and mirrors, raising their temperature just enough to stay above the dew point. But here's the catch: dew heaters require power, and that's where batteries come into play (unless you are close to AC outlets).

When it comes to dew heaters, there are a few different options to consider. Some are designed specifically for telescopes, while others are more general-purpose and can be used on a variety of optical equipment. The key is to choose a dew heater that provides enough heat to keep your lenses and mirrors dew-free without overheating them. Look for models with adjustable temperature settings and built-in thermostats for optimal performance.

Overall, a dew heater is essentially a flexible band, typically made of rubber, fabric, or similar insulating materials, designed to wrap around the optical elements of a telescope, particularly around the lens or corrector plate. Its primary function is to gently warm these areas, preventing the formation of condensation or dew, which can obscure your view during observations, especially in humid or cold conditions. By maintaining a slight temperature difference between the telescope's optical surface and the surrounding air, the dew heater ensures that moisture doesn’t condense on the lens.

Dew heater battery options for your astro rig setup

Once you've chosen the right dew heater, the next challenge is finding a reliable power source. Most dew heaters are designed to run on 12-volt DC power, which means you'll need a battery to keep them running throughout the night. There are a few different types of batteries to consider, each with its own pros and cons.

Lead-acid batteries are a popular choice among amateur astronomers because they're relatively inexpensive and widely available. They come in a variety of sizes and capacities, so you can choose one that meets your specific needs. However, lead-acid batteries are heavy and bulky, which can be a drawback if you're planning to transport your equipment to different observing sites. They also require regular maintenance to keep them in good working order.

If you're looking for a more portable option, lithium-ion batteries are worth considering. These batteries are much lighter and more compact than lead-acid batteries, making them easier to transport and set up. They also have a longer lifespan and require less maintenance. However, they tend to be more expensive, so you'll need to weigh the cost against the convenience.

For the environmentally conscious astronomer, solar power is an intriguing option. By using a solar panel to charge your battery during the day, you can keep your dew heater running all night without relying on traditional power sources. This can be a great solution if you're observing in a remote location with limited access to electricity. Just be sure to choose a solar panel that's compatible with your battery and provides enough power to keep your dew heater running.

Batteries and dew heaters: My setup

After much trial and error, I've finally settled on a setup that works for me. I use a lithium-ion battery to power my dew heater, which I wrap around my telescope's primary and secondary mirrors. I also use a smaller dew heater for my eyepiece and finder scope. To keep everything running smoothly, I invested in a solar panel that I use to charge my battery during the day. This setup has been a game-changer for my astrophotography, allowing me to capture stunning images without worrying about dew ruining my equipment.

Options for portable batteries

• Anker SOLIX C1000 Portable Power Station - 1056Wh | 1800W
• Apertura Portable Telescope Power Supply - 155Wh
• Nitecore D4 Universal Battery Charger - Includes rechargeable batteries and a versatile charger.
• TalentCell Rechargeable Lithium-Ion Battery Pack - Popular for its high capacity and portability.
• Bioenno Power LiFePO4 Battery - Known for long life and stable performance.
• Jackery Portable Power Station Explorer 240 - Provides a high capacity and multiple charging options.
• Goal Zero Yeti 200X Portable Power Station - Compact, with versatile output options.
• Duracell Ultra Power - Reliable and widely available, ideal for smaller devices.
• Viking Lithium-Ion Battery - Lightweight and suitable for various astronomy equipment.
• Renogy 12V 100Ah Lithium Iron Phosphate Battery - Known for durability and long-lasting power.
• EcoFlow River Mini Portable Power Station - Compact and efficient with multiple output ports.
   

Additional tips and tricks to keep your telescope lenses dew-free

In addition to using a dew heater and battery, there are a few other tips and tricks that can help keep your telescope lenses dew-free:

1. Use a Dew Shield: A dew shield is a simple, inexpensive accessory that attaches to the front of your telescope and helps to reduce dew formation by blocking moisture from settling on the lens.

2. Keep Your Equipment Covered: When you're not actively observing, keep your telescope and other optical equipment covered with a protective cloth or tarp to prevent dew from forming.

3. Monitor the Weather: Pay attention to the weather forecast and plan your observing sessions accordingly. If the humidity is high and the temperature is expected to drop significantly, take extra precautions to prevent dew formation.

4. Stay Vigilant: Even with a dew heater and battery, it's important to periodically check your equipment throughout the night to ensure everything is working properly. If you notice any signs of dew formation, take action immediately to prevent damage to your optics.

As amateur astronomers, we face many challenges in our quest to explore the night sky. Dew is just one of those challenges, but with the right tools and techniques, it can be overcome. By using a dew heater and a reliable power source, you can keep your telescope lenses clear and capture images of the cosmos without worrying about dew collecting on your lenses.