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Old 05-28-2014, 12:39 AM   #5 (permalink)
mwebb
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Join Date: Jul 2009
Location: New York
Posts: 510

no nickname , it's just a car - '04 volkswagen golf tdi
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calculated load

to keep it simple
just keep it simple , do not make this more difficult than it is

engine load is measured by calculated load or engine load
most OBD2 scan tools can monitor this PID
Parameter ID

better to graph or log it

if all else is the same , changes in alternator usage will show in calculated load

DO NOT CHARGE THE BATTeRY PRIOR TO TESTING IN THIS MANNER -

so
use A B testing
install battery A drive the car with no loads on so the system will charge the battery to whatever value it chooses,run the system long enough to allow the system to become stable , let the car sit over night
now
pick a drivecycle you can duplicate

drive the car and remember all load settings ie high beams on , heater blower on , ac on whatever , just repeat these values next drive cycle
and graph / log calculated load

repeat with battery B

the log / graph with lowest average calculated load is the more efficient battery / alternator system combination .

in the mean time
keep all voltage drops as low as possible , losses across the ground or battery positive cable at max alternator load should must be
under
300mv
on each side

lower is always better
DVOM set on DC volts across cable to be tested
ie
battery positive terminal on the lead NOT THE CONNECTOR (battery terminal) to alternator B+ post
and
battery negative terminal on the lead NOT THE CONNECTOR to alternator case
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