Is my Alt dead?

DorianL

solid fixture here in the forum
Staff member
Or was my battery just Uber flat?

What do you think?

If I recall correctly - I have a 130 Amp Powermaster on there. The biggest drains at idle are the two electric fans which can draw a total of 50 Amps.

I was turning the car on and off at the race + it was a hot day. Suddenly the engine wouldn't come back up again - right when I was going for fast runs! I checked the batt: 11.84 volts!

I had some one jump me and drove for 40 minutes cruising around... I came back and the batt as at 9.20 volts. Not charging. Sooo, I checked the alt - the remote voltage sensing wire was loose. I reconnected it but was still reading only 12.4 volts at idle + somewhat erratic.

Anyway - someone fully recharged my batter overnight and gave me a good. 12.9 on the battery.

At idle the next morning I was readiong 14.0 volts. When fans came on, this would drop down to 12.x

Is the regulartor dead? Is the alt not "big" enough? Should I get a 160 Amp alt?

When I cruised the 200k back, there was no issue... but not traffic or need for eletric fans either. I was reading 14.0 volts at the battery everytime I checked.

Hmmm,

What thinkgs you?
 
these threads and sub links should help, but it sure sounds like the alternators failed, personally ID suggest a 160-200 amp alternator, as IVE seen many times where adding one helps far more than you might suspect it would, installing a 200 amp alternator has always made my engines run better, jist be aware youll NEED a new 4ga-2 ga power lead between the battery positive terminal and the new alternator to get it to function correctly, ask the guys at the supply house for detailed instructions on installing the new alternator, and ask if you need adapters or changes in wire connections




altinfo.jpg


http://www.dbelectrical.com/c-4913-200-amp.aspx

http://www.dbelectrical.com/p-9594-alte ... -1993.aspx

viewtopic.php?f=36&t=3222&p=8575&hilit=test+alternator#p8575

viewtopic.php?f=53&t=2044&p=5451#p5451

viewtopic.php?f=70&t=6961&p=22863&hilit=test+alternator#p22863
 
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Do any of you 2 upgraded the wiring to use higher amp alternator or its fine with the factory 10 gauge?
 
I upgraded. But also feel that my 130 or 140 Amp (?) alt Powermaster is just not enough to drive those twin fans at idle
 
I(f you have a high performance car, with electric cooling fans, a sound system and a high performance ignition, your almost sure to find your alternator is running at or near its limits at times, the simple answer is to upgrade the alternator. buy a 160-200 amp alternator
if you care to ask why?
Heres some math,(link below) all you need to is calculate what the radio, sound system, starter, performance ignition, alarm system, air conditioning head lights, cooling fans and a dozen other things like power windows and power seats draw to quickly see why the stock alternator if marginal at times.
these threads and sub links should help, but it sure sounds like the alternators failed, personally ID suggest a 160-200 amp alternator, as IVE seen many times where adding one helps far more than you might suspect it would, installing a 200 amp alternator has always made my engines run better, just be aware youll NEED a new 4ga-2 ga power lead between the battery positive terminal and the new alternator to get it to function correctly, ask the guys at the supply house for detailed instructions on installing the new alternator, and ask if you need adapters or changes in wire connections

OEM alternators are marginal at best
swapping to a 200 amp alternator, is generally money well spent!
the upgrade, usually speeds up the cooling fans,
increases ignition spark strength, and brightens head lights
I noticed an obvious improvement on both my corvettes after upgrading to a 200 amp alternator

1996 vette
https://www.summitracing.com/parts/pwm-478648
https://www.summitracing.com/parts/pwm-378068


1985 corvette
https://www.dbelectrical.com/produc...MInZDL6u-X3gIVCo7ICh3cVgA5EAQYAiABEgKGnPD_BwE

http://www.powerstream.com/Amps-Watts.htm#amps-watts

I upgraded to a 200 amp rated alternator on my 1985 corvette, I also per the instructions that came with the alternator,upgraded the cable gauge too a serious GAUGE copper connection cable, I ran a new 2 ga from the alternator output stud, but a 4 ga should work

http://www.madelectrical.com/electrical ... ire3.shtml

http://www.madelectrical.com/electrical ... remy.shtml

viewtopic.php?f=70&t=2133&p=5744#p5744

http://www.summitracing.com/parts/bss-c ... dia/images

the NEW REQUIRED UPGRADE, 4 ga wire used to charge the battery on a 160-200 amp alternator used to upgrade from a stock 70-90 amp alternator should run between the alternator power out directly to the battery positive, 4 ga is not heavy enough to run from the battery positive terminal to the starter

http://www.dbelectrical.com/casearch.as ... ageSize=60

wolthuis.aspx.jpg

alter1.jpg

alter2.gif


directly to the battery positive terminal ,then ran an extra 2 ga ground from the battery neg to the cars frame and a new ground ribbon cable
tay-148014.jpg

between the frame and engine block.
the result was far more than anticipated, the engine ran smoother at all rpm level, the cooling fans ran noticeable faster at idle and the engine ran cooler, the ignition spark also seemed to be stronger and brighter and the electrical arc,s snap sound louder when you pulled a plug wire off a plug to test spark on an idling engine, keep in mind the alternator pulley tends to be about 1/3rd smaller or even less than the crank pulley diameter, so that the alternator spins at least 1200rpm , below that 1200 rpm many alternators don,t put out nearly a full charge


http://www.summitracing.com/parts/SUM-G1198/?rtype=10

SUM-G1198_SN.jpg


http://www.powermastermotorsports.com/f ... ators.html

http://www.jegs.com/p/Powermaster/Powermaster-GM-CS144-Style-Alternators/1534945/10002/-1


http://storesense1.mysuperpageshosting. ... &total=111

viewtopic.php?f=53&t=2044&p=5451#p5451

http://www.dbelectrical.com/p-4416-new- ... -11se.aspx
 
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DorianL said:
I upgraded. But also feel that my 130 or 140 Amp (?) alt Powermaster is just not enough to drive those twin fans at idle
What kind of alternator model do you have Dorian?
did you stay with a 10si or 12si(i do use a upgraded 10si) but the cheaper more availlable cs-130(105A) and cs-144(140A) unit is a better choiche(wish i knew that a few month ago) if your willing to do some wiring.. they have more output Amps at idle wich is more suitable for the high load that some electrical fans need at idle or low rpm and they have better cooling.

As for upgrading the wiring its a good idea with such amp rating :D
 
Right, we have an answer... and that is thanks to reading through Grympy's links, particuarly the Powermaster FAQ.

A new Alt is NOT required. The supercharger required an offset pulley to clear its belt. The diameter of the offest pulley was larger than what was originally on the alternator.

At 800 rpm with fans on (and alt heating up) the voltage drops from 14.00 to 12.40. If the rpm drops more (in Drive) that voltage gets erratic.

If I bring the rpm up to 1100, with both fans on, the voltage comes back up to 13.50

Analysis: the pulley is too small and is underdriving...

Thanks Grumpy!

D
 
Yep, the old 10si-12si need some rev at idle to work properly.. its best to go a little more overdrive that stock.
 
yeah! taking the time and effort needed, for reading links can do far more than blindly spending sparse case reserves, yet most people would rather be skinned alive and rolled in alcohol and salt that read links
 
Its a good thing you talk about the battery to chassis ground, i totally forgot this one.

Right now i have double 0 from batt negative to the engine, double 0 from the batt positive to the starter, 2x10 gauge wire from the alternator to the starter(where it meet the double 0 to the battery)
I used 2x 10 gauge because the stock wire was already a 10 gauge and since i had a roll of 10 gauge availl and two 10 gauge together make for 4 gauge(wish is good for 135A) thats what i did. Routing a new 4 gauge wire and finding a 140+A fuse(since a 8 gauge fusible link does not exist) is a little more that what id like to do.
The stock 10gauge wire use a fusible link (14-16 gauge in most app including mine)
now there is no fusable link for the other 10 gauge wire so am gonna be using maxi fuse of 60A.
Yes i know alternator is 140A but the way i see it is, there is no extra load on the stock wiring, the only extra load is at the batt positive terminal(32A that include my fan, ignition, water and fuel pump) and 2 10 gauge together make for a 4 gauge wisch is good for 135 A.
single 10gauge is good for 55A, so its good for a 60A fuse(since its a fast blow and only in case of major circuit shorts) and my 32A load.

I will be using double 10 gauge(equal to 4 gauge) wire from batt negative to the chassis ground.
I think i will be good?
 
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