I guess it would really depend on how much juice is still in there, or if it's just been cleaned and dried, and how much juice your cartos hold (mine hold a full 1ml). Here's how I refill cartos that I've used during the day:
• At the end of my day, I condom fill all 4-5 of them. Fill the condom up about 80%, then dunk in the battery end. I like to see just be a minimal amount of pooling up on top. Drop in more if they still look dry. Then I let it sit like that overnight.
• The following day, I pull the condoms out about halfway,
flick them like thermometers about 10 times, and wipe down the posts. What's left in the condoms is how much you've overfilled, and you can adjust how much you drop into the condoms accordingly. Or you can keep doing it the same way, and use the remaining juice for your next fill or pour it back into the bottle (haha, which I'm too lazy to do. I usually just keep it in there for the next fill.). No need to worry about the juice evaporating. I think the PG does a good job of keeping this from happening. I had a little juice in a condom for over a week (ick, didn't use it) and I swear, I don't think it
ever evaporates. No need to worry about overfilling either. The flicking takes care of that.
If you want them to last all day, I think the trick is to let it sit with ample juice for as long as you can, so that the filler has time to really get saturated. The thicker your juice (i.e., the more VG it has), the longer this takes. Also, in my experience,
refilleds never really last quite as long as
prefilleds, especially when the carto gets really old. That's why I fill them the night before, and carry more than one...but I vape like a chimney too, which is why I go through 4-5...
