If you really want your hydrogen generator to work, you should use the field wire off the alternator. Amps are a result of applied voltage to X watts. (A=W/V) Watts don't change- unless the equipment changes. The field wire will vary voltage, higher voltage will lower the amps used. You should be able to estimate your amperage (load) using the formula Amps=Volts/Resistance (ohms). I would still use 11v to figure the load- like it was on a battery.
Other than that, from what I understand you should be careful of using too much hydrogen as it burns much hotter than gasoline. If what you have is working, and has been working, then you should be ok. For kicks, research "hydrogen cutting torch", as that is an easy HOH project.
I personally haven't tried hydrogen, but I have tried other things. I quit messing with acetone because it's a pain in the ass- not because it doesn't work. If you use too much, you lose MPG, and the effect is diminished when using E10 gasoline that is freaking everywhere now. Magnets work, but no magnetic fuel saver that you can purchase works. The magnets you have to use are simply too expensive for profit. The gains are not tremendous- merely 3 mpg on a Focus, I have no idea what it does on other vehicles because the van is down at the moment. I have high hopes for 5.
That might help the OP, but it's not his/her problem. For those of you who haven't been here that long- this happens EVERY YEAR. Winter screws fuel economy. With carburetors, winter helped- if you could get the darn thing started. Not so with EFI, especially EFI that varies fuel with ambient air temp to keep the A/F correct. Everyone's fuel economy goes down no matter what trick they are using. I block off my part of my radiator to increase the engine temps because I believe that my all aluminum engine is overcooled- and it does help with MPG. Not to mention my wife doesn't complain because the heat fires up much quicker.
Focusmanic- I'm sure some people would be interested in your project, but you can expect other people to be adamant about opposing it because Mythbusters (sponsored by BP) says it doesn't work. In fact, they said no gas saving tricks work, so just give up and invest in oil sometime before we elect another R president.