What is Reddit's opinion of Dew Heater,Lens Defogging Heater Condensation Prevention Lens Warmer, Fast Warming for Universal Camera Lens,Telescopes,Coffee Cup,Baby's Bottle?

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Consider a 10w Lens heater.

It's used to keep telescopes and cam lenses warm, but they pitch it as multi-purpose. Now, I'm not thinking it's gonna keep my tea hot, but it could stave off freezing on the bird feeder.

https://www.amazon.ca/dp/B08LGN222F

I have pretty large (2" wide field) eyepieces, so I purchased a camera lens dew heater and just wrap it around the eyepiece directly. The eypieces are smaller than a camera lens so it wraps around a bit but still works. This is the one I bought: https://www.amazon.com/gp/product/B08LGN222F

They are power hungry. I connect it to a 10,000 mah cell phone power bank and have gone 4 hours or so and think I have a little less than 50% left. It would run dry in an all nighter.

I have mostly ran it on medium, but haven't really tested low yet. It might work and use less current.

 

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Oh, btw... here is the one I bought:
https://www.amazon.com/dp/B08LGN222F?psc=1&ref=ppx_yo2_dt_b_product_details

I used an old 10,000 mAH cell phone battery for a couple hours one night and it burned through about 50% of the battery. I had it first on high setting, then on medium. Need to try low next time. When you put your eye up to the eyepiece, there is a noticeable electrical smell coming out of the eyepiece strap. I'm thinking of moving it down on the eyepiece next time to test how well it works a bit further from my nose...