electric water pump vs. alternater belt

we run 2 batteries in the trunk...and still use an alternator...if you are looking for every last hundred...the extra battery might cost ya,,,, .04 for 40 lbs in the trunk...but gives ya the weight over the rear tires...

and we still use alternators on the cars,,,,bracket racing needs consistency...and fully charged batteries help that
Being a rally guy, drag racing is a different world to me. Just curious on another point...... anyone cut off the alternator (cut the field current) in a drag run to keep the alternator load off the engine for that time, and then turn it back on when the run is done to re-charge? Especially if running an electric pump.... that is just that much more load being run by the engine that could be just sourced from the battery. Or does the higher voltage keep the spark hotter and help?