I had trouble with Coolcarts recently, which is why I still prefer the premiums. I noticed that the filler inside the coolcarts was packed too tight. When I filled them, they overflowed without ever really getting saturated. Then naturally, after a few puffs, the wick went dry and charred. The only way I could get them to work past the "break-in" period, was to fill to near overflow and then work the stuff into filler by pushing into it with a needle. The resistance on the needle also tells me the filler is too tight. I would have to repeat this several times and just got annoying, so went back to premos. On the upside, if you do get past that first filling and the filler starts to loosen up, subsequent fillings go very much like past cartos.
Ever buy brand new bath towels and notice they put too much sizing in that it is stiff and doesn't dry you very well? Then after you use it a few times and have it go through a wash or two...then it sucks up the water real easy? Well...the coolcarts are like that. They don't work well brand-spanking new, but just fine later, if you want to take the time to nurse them through the first use. Anyway, just my 2 cents.