I have a questions about max amps & power supply.

I develop SHOGEN
i'm using tubes rather than plates. a cell of mine consist of 2 stainless steel tubes. inner for anode, outer for cathode. to make the neutrals, I use 4 cells connect them in series. i connect the first cell anode and last cell cathode to power supply.
i have 2 power kind of supplies. 1st is car battery charger with max 12 volt 12 amps, 2nd is computer kind power supply with max 12 volt 33.3 amps.

I try use one power supply, i check with multitester, each cell volt is 2.6 volts. this is acceptable for me, 12 volts devided 4 is 3 volts. 2.6 volts is near enough.
but when I check amp, it only consume around 7 amps. not 12 amps, not 33.3 amps as it's written for both power supply test.
when I pararel 2 of them together I get 14 amp consume & doubled gas production.

these are the questions:
1. is this mean my SHOGEN's max consumtion is 7 amp, 14 is forced. or the power supply vendor fooled me? I mean the max output of both power supply is just 7 amp, not 12 nor 33.3 as written.
2. how to force amp to cell ? what kind of power supply should I use ? or should I modify my power supply to get bigger amp? I have feeling my cell can take more than just 14 amps. i want to try up to 30 amps but don't know how.