It is wrapped with shrink wrap from McMaster, per the Smack design. I added the 2 extra plates on the ends per the modified Gen I design, shrink wrapped the straps, and then the whole cell after conditioning it. It just gradually heats as it runs, until it maxes at 201F. I found a digital wireless meat thermometer with a stainless probe at WalMart for $14, drilled a hole in the top of my cell, and permanently mounted it to my unit so I can monitor the heat of the cell. I hit 180F after about 45 minutes, and should probably stop it there. I let it run yesterday for 3 hours, and it levels out at 201F. However, I am using 1/8" clear extruded acrylic tube, and 200 is too hot for continuous use. What I didn't do with my last run is monitor amps, and it is possible I have too strong an electrolyte. But apart from the thinner tube, I am built per Smack specs. If you look at the latest data Smack posted on his Gen I and Gen II designs (http://smacksboosters.110mb.com/genIIdata.pdf), you will see that both his cells run at over 90C (194F), which makes me think that this is just a design that has to run hot.

Thanks, but I'm still trying to figure quite a bit out, actually. I've tried a few different designs, including a bunch of unsuccessful attempts with some 316 fine mesh wire I was given, and have 2 smacks built so far. I am trying various bubbler configurations right now, to satisfy myself that my booster will be safe when I put it in my Saab. I've also been accumulating gas mileage info on my car, so I can get some scientific results when I start using the booster. I haven't taken any pics yet, but will shortly, probably tomorrow after I finish my latest bubbler attempts. I just got some tube in from McMaster today, and will have some time tomorrow to play with my setup. I may run it again today for a few hours, and measure amps with temp to make sure I am not over pulling current. I am hesitant to get it up to 200F again, because the acrylic deformed a bit in my last hot run.

The original Smack design used a piece of flexible nylon tubing glued to the side of the pipe. I could never get the tube straight, had a hard time getting the connectors to seal properly, and wasn't comfortable with that being the only line of defense between my cell and a flashback. I've built a couple out of 1 1/2" PVC, with screw off lid with clear plastic on it so that I could check the water level without using a sight tube. I also built a couple out of some Wamart pet water bottles that are clear with level markings on them. I just got some acrylic tube in today, along with some rubber stoppers, which is what Smack uses on his Gen II. I think these will work much better, and will fabricate a couple tomorrow to test.

I ran another set of tests today, and measured amps, volts, temperature, and rough output over a couple hours. Here is the data I got:

Time Temp(F) Volts Amps
0:00 63 12.24 9.9
0:15 87 12.3 13.96
0:30 109 12.18 14.5
0:45 132 12.02 17.28
1:00 155 11.91 18.5
1:15 175 11.92 18.28
1:30 191 11.84 20.5
1:45 200 11.82 22.21
2:00 201 11.58 18.43

At two hours in the temp stabilized, and my bubbler started to fail, so I gave up before did any damage to the cell casing. Amps weren't that bad, maxing out at about 22, and like my last long trial the temp stopped at 201F. The output was fairly consistent at about 1L per minute. By the end I saw some noticeable vapor in the gas coming out.

I took a few pics of my setup with my cell phone before I started, and will try to put them up in a bit. I want to break down the cell and take some pics of the guts, too.