Normal "engine running" 6 volt charging system voltage is 7.5 or a bit more. The only time an actual 6 volts will be seen is when the engine is stopped. Whomever designed the Runtz system knew what he/she was doing.

Normal "12 volt" system operating voltage is 14.7. People get so wrapped up in terminilogy that they conveniently ignore what's actually happening.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!