Oh man I have two of those and the other day I took a sip of chunky coffee because it was the week old one that I forgot about.

Yeah, I typically hate brand name stuff, but 100% of my knockoff tumblers and bottles have had their vacuum fail in under a year while my free yeti has been going strong for 5 years.

I actually have to add cold water or ice to be able to drinking it within 2 hours.

You can use a plug-in candle warmer to fairly good effect, as long as you start with hot liquid.

There's a $40 one sold at Walmart, Ion brand, no app at all, plugs in the wall, not USB.

It worked well... for about a year. The metal contacts on the bottom corroded, and the battery duration dropped. I'm using a four-dollar candle warmer now, it's the better choice.

This one:

https://www.walmart.com/ip/ionMug-Charging-Coaster-12oz-Stainless-Steel-Self-Heating-Coffee-Mug-with-Lid-3-5-x-3-5-x-5/809689677

I tried this with tea, as a regular coffee drinker, and immediately burned my mouth off. It doesn’t cool down the same speed as my coffee in the same mug, because there’s no milk added to pre-cool it.

If I try it again it would have to be cooled with ice, and I probably will because I don’t like cold tea much, but if I wait for it to cool on its own I’m likely to overshoot and end up with cold tea.

My partner and I got one each. She stopped using hers so now I have one on charge all the time.

Also! If your charging base contact pins get sticky and corroded, a spray of WD-40 and some light poking fixes them right up, and seems to delay further issues.

I’m so tempted by these things.

I drink a lot of cold coffee because I forget I have coffee.

if you're by Placerville I left a blue one up there you can have