I posted this over on the Coleman Collector's Forum. No experience there so far with the Coleman Powermax canister. "I've been fortunate to acquire all three (that I know of) Xtreme stoves that use the Powermax canisters. I've only been camping/backing once where I used the 3 legged Xtreme stove and it seemed to slowly go down in performance a few weeks ago fixing pancakes while on a short distance backpacking trip. I've tried this same canister, it being partially used when I got it, at home too. Last summer it ran great on the stoves. Seems since the temperatures are colder, this same canister isn't putting out very good, even after running a bit to get the generator warmed up. I tried a new canister this AM and the stove ran like it should but when the partial, used canister was tried again, the stove was just above a simmer. Faulty canister, pick up hose set due to the cold at a bad angle?" Anyone else have issues, or just this one canister? Duane
Hey, HD, So far, I've not experienced any such problems, but admittedly, I've not backpacked with those stoves, and only used them when car camping. With the snow outside, and high winds blowing, it might be a good time to do some testing, up on the ridge behind our home. Too much to do today, but maybe I can get it done this weekend. Take care, and God Bless! Every Good Wish, Doc
Ed, the canister still has a quarter or so of the fuel left. I'll have to weigh it to get an idea of how much fuel is left. Even if the fuel separates at lower temps (not sure of the blend) the stove should vaporize it. Duane
With fuel sloshing around in the canister you might not unreasonably expect that the stove would burn fuel in that characteristically Powermax lively fashion right up to the last drop, HD. My experience with these though is that the propane/butane mixture creates the phenomenon you've described sometimes - but not always. I believe that on occasion the propane content is used up before the butane and you're then left with just the butane, which of the two gasses is the one that most suffers from vapour pressure reduction due to evaporative cooling - propane virtually not at all. When the propane's gone, the power of the stove reduces dramatically, especially at this time of the year with lower (sometimes very much lower) outdoor temperatures. I've a theory - though I can't present it with scientific rigour - and it's that however consistently Coleman charged Powermax carts with a fixed proportion of propane to butane, there's nothing to regulate and maintain that same proportion in the gasses that burn. I expect that atmospheric pressure and ambient temperature influence that significantly. I expect that the butane is used up first sometimes, when the stove would most likely behave as a propane stove - powerfully to the last. Powermax sectioned cartridge John
Thanks as usual John. Since I have so many stoves, some only get a field trip now and then, so we'll have to see when I take one of these out again. Maybe the partial canister can be used this summer and a fresh canister this winter if it makes the cut. I remember last summer that the stoves pot supports got red like your link shows on the canister in question. Duane
Most probable cause: flexible internal tube inside the canister detached from top valve, or cracked. I believe this is the real reason for stopping production of such canisters. The pickupp tube is meant to bring to the stove LIQUID gas, where it vaporises. This is the only way to avoid propane boiling out from the mixture, leaving in the canister, the much less volatile butane. Orsoorso
Oorsoorso's made a valid point sure enough. If the pickup tube has detached itself from the valve (as opposed to merely split) it'd create even more of a rattle when the cartridge is shaken than it usually does when still attached to the valve. John
I'm aware of what the pickup tube does, but good point about it being detached or cracked. I can hear I'm guessing the end rattling around. My thought also was it has retained a curved shape from sitting in one position and when moved, it keeps that shape due to age and the cold as this canister in question is laid on its side versus standing up like my other canisters due to space. (I have more than what I made storage room for.) When I empty it sometime down the road, I'll open the canister up and see because I was under the impression that the Powermax canisters would work to much colder temps, not the warm, balmy teens/low 20'sF I've had the stove in. Duane
Duane, are the Powermax canisters like the Hank Roberts? Liquid feed? So the tube would be down in the liquid no matter what position the canister is in? Just a thought. Oh, another thought, if the fuel does separate, the butane may not vaporize at the lower temp that the propane will vaporize at. Ken in NC
I have had the sme experience with my Powermax cartridges, ie in cold weather(freezing) with low fuel levels, power drops dramatically as the cannister gets cold from use. If you heat the cartridge it will work fine again until it gets too cold, again. I too suspect that somehow, the propane portion sometimes burns off first, leaving butane behind which is well known for lousy cold weather performance. These are liquid feed cartridges. The rattle you hear is a metal weighted tip on the end of a plastic hose that is supposed to keep the fuel inlet below the liquid surface. This poor cold performance was also a surprise to me due to the advertising touting good cold performance. Without my Coleman white gas stove, we would have gone without hot food etc on several occasions had we relied soley on the Powermax stoves. Powermax stoves are nice gaz stoves but I no longer consider them a 4 season stove. Jim Henderson
Here's the sectioned cartridge ... ... and the metal portion of the pick-up tube that ensures that so long as the cartridge is laid on its side the tube's always dunked under the liquefied fuel Looking at that arrangement, that steel part of the pickup tube is never going to bend, but a split in, or detachment from the valve of, the plastic tubing part is always possible. Or, it's fractioning of the two gasses in the fuel that's wholly responsible for the symptoms after all. John
Add ... In the Hank Roberts gas cartridges, there's no pick-up tube as such, but a cotton wick dunked in the liquefied gas delivers fuel to the outlet valve. John
Thanks Jim for the re-enforcement of my thoughts and my experience. When I used the stove out in the real world, temps were in the mid '20'sF if I remember right. The cold weather performance must come from a new canister before it is half used up. Here I thought it would be a great winter stove with its ability. Duane
For anybody who hasn't yet seen it, there's an epic discussion of canister stoves and their cold weather operation on the Fäderlätt site. It starts in the fourth topic.
An after thought. I have been able to get a MSR isobutane canister with my old Pocket Rocket to work in single digit F temps before, just by dunking the canister in water. I'll try that on the Powermax to see if anything changes. Forgot all about doing that. Duane
