They’re going to have an absolutely tiny battery. Somewhere around 50-300 milliamperes so i would imagine no more than 30-45 minutes regardless of what wall wart you have them plugged in to.

When you say juice, do you mean vaporizer liquid or battery ‘juice’ (capacity)? Im going to assume y oh mean battery capacity since the only way to fix the vape juice issue is more juice or a new disposable.

Battery starts at 4.2ish volts. As battery gets used, voltage drops. 2.8-3.2 volts is usually considered ‘dead’, depends on charge controller. When approaching 2.8-3.2v the battery just doesnt have the nuts to drive the coil. The result is less vapor produced. Less vapor produced means flavors are washed out or muted. Sweet flavors also tend to gunk up coils, which can also mute flavors/vapor produced.

It's conceivable that running at a lower wattage could crud up the coils more quickly, so charge it all the way. I hope this goes without saying, don't make a disposable your main vape it's obscenely wasteful

Would recommend looking into small USB charged non disposable vapes. I got an xros 3 starter pack for around the same price as 1 disposable vape ($30) and it's lasted me over a year so far. I only need to buy juice like once a month and new pods every other month

Battery lasts a few days and fully charges in less than an hour

Fully charge it. Does it have an indicator light for charging vs full? Even the most garbage of vapes shouldn’t let you over charge the battery. Just leave it charging until it’s full and top it up from time to time.

The battery in your vape is the same type that’s in your phone.

Is it a built in battery? Those are a bit harder to gauge compared to removable li-ion batteries

I don't think charge time has anything to do with it.

You can also refill the Lost Mary ones at least if you gently pry off the top. It probably works for most of the others.