With a -N+N-N+N-N+N-N+N-N+N- @12V you will have a 6V per gap voltage drop. You only need 2V per gap anything more will generate heat. While you might get it to run for a few minutes, after several hours it would overheat and self destruct.
For a 12V setup it is recommended that you use +NNNNN- 7 plates total. You can also string this setup together in series +|||||-|||||+|||||-|||||+|||||- etc. This will give you more plate surface area without increasing the voltage requirement. This concept works with both wet and dry cells.
Hope this helps.
--
Some days I get the sinking feeling that Orwell was an optimist!