I bought the submersion heater for a grid down situation to be used with my otherwise also new Yeti200X.
I heated 250 ml water up to 85 Celsius (not a rolling boil, just a beginning one) in 12 mins. This took 16% out the full powerbank.
The heater hangs over the rim of a mug but not my enamelled ones (rim too wide). It sat a bit too wobbly with the cable still a bit stiff and top-heavy.
Up till the sixth minute the heat was climbing by 10 Celsius steps per minute, after that it slowed down.
I will obviously have to do more experiments as to how long the Yeti takes to recharge from my balcony as compared to the 400 ml water brought to 90+ Celsius in the GoSun Sport Brew which can take (over) 2 hours this time of the year.
This submersion heater
is light and small, thus very handy to pack. It can be used in the car and will get you a hot cup of instant coffee in about a quarter of an hour which seems very reasonable on the road.
In my case it would be used on rainy days, after sundown, indoors and without using candles, fire, or gas. In comparison, my tiny one-person Italian coffeemaker also produced about a thimbleful of espresso after 21 minutes over a candle.
Compared with the size of my power bank that might heat 5 such cups before it's empty, I will most likely use the submersion heater sparingly, as a backup, like I planned.