Measuring alternator charging current

infernosg · 08-30-2018, 12:20 PM

I never read anything but bad reviews for the "upgraded alternators." Shortened life and low voltage at idle speeds seem to be the common complaints. A few companies make claims against the latter (IR Performance offers a S6 alternator upgrade) but I'm skeptical. Have you considered one of the "common" upgrades like a S6 (100A) or Ford Taurus (130A?) alternator? Based on the loads you listed there isn't much you can do to reduce them. LED taillights and perhaps a more efficient/variable speed e-fan are probably the best options.

I'm in the process of upgrading my charging system as well. My car has significantly less sources of draw. Outside of the "normal loads" the only additional loads are the electric cooling fan and cabin blower motor. My biggest issue is low voltage at idle due to the Racing Beat underdrive pulleys. I had a Banzai Racing alternator pulley but it was eating belts for some reason. I'm going to try a S6 alternator with their v-belt pulley next. Hopefully that will bring up the idle voltage and the extra current headroom can't hurt. LED taillights in the future too.

Pete_89T2 · 08-30-2018, 02:32 PM

^Same here, high output rebuilt alternators tend to be a crap shoot. Although the one I have (110A vs the stock 80A) doesn't have any problems with maintaining voltage at idle speed. I'm using a dual belt pulley, but it's not an under drive type.

An S6 alternator wouldn't be an upgrade over what I have now - I know the "rated" 110A alternator I have now is putting out at least 100A, as I was able to get my 100A sensor to read an over range condition (displays FFF when > 100A) by flipping on everything shortly after starting the car, when current draw maxes out. Thought about the Taurus alternator, but don't like the fitment - too tight with the stock TMIC. Someone needs to publish an alternator cross ref database that you can drill into by technical specs - case/mounting dimensions, electrical output/interface & pulley specs.

Going with LED equivalents for everything outside except for the headlights & fog lights will reduce power consumption by roughly 85% (e.g., a 27W halogen 1156 gets replaced by ~3.5W LED, for similar light output), so I'll be doing that soon.

08-30-2018, 12:20 PM	#1
infernosg IT'S ALIVE! Join Date: Dec 2009 Location: Richmond, VA Posts: 811 Rep Power: 16	I never read anything but bad reviews for the "upgraded alternators." Shortened life and low voltage at idle speeds seem to be the common complaints. A few companies make claims against the latter (IR Performance offers a S6 alternator upgrade) but I'm skeptical. Have you considered one of the "common" upgrades like a S6 (100A) or Ford Taurus (130A?) alternator? Based on the loads you listed there isn't much you can do to reduce them. LED taillights and perhaps a more efficient/variable speed e-fan are probably the best options. I'm in the process of upgrading my charging system as well. My car has significantly less sources of draw. Outside of the "normal loads" the only additional loads are the electric cooling fan and cabin blower motor. My biggest issue is low voltage at idle due to the Racing Beat underdrive pulleys. I had a Banzai Racing alternator pulley but it was eating belts for some reason. I'm going to try a S6 alternator with their v-belt pulley next. Hopefully that will bring up the idle voltage and the extra current headroom can't hurt. LED taillights in the future too. __________________ '86 Mazda RX-7 Base '79 Mazda RX-7 GS

08-30-2018, 02:32 PM	#2
Pete_89T2 Lifetime Rotorhead Join Date: Apr 2010 Location: Elkton, MD Posts: 874 Rep Power: 16	^Same here, high output rebuilt alternators tend to be a crap shoot. Although the one I have (110A vs the stock 80A) doesn't have any problems with maintaining voltage at idle speed. I'm using a dual belt pulley, but it's not an under drive type. An S6 alternator wouldn't be an upgrade over what I have now - I know the "rated" 110A alternator I have now is putting out at least 100A, as I was able to get my 100A sensor to read an over range condition (displays FFF when > 100A) by flipping on everything shortly after starting the car, when current draw maxes out. Thought about the Taurus alternator, but don't like the fitment - too tight with the stock TMIC. Someone needs to publish an alternator cross ref database that you can drill into by technical specs - case/mounting dimensions, electrical output/interface & pulley specs. Going with LED equivalents for everything outside except for the headlights & fog lights will reduce power consumption by roughly 85% (e.g., a 27W halogen 1156 gets replaced by ~3.5W LED, for similar light output), so I'll be doing that soon.