Excessive Ripple???

98E9GT

New Member
Dec 16, 2007
110
0
0
I had my charging system tested today and it failed, tester read Excessive Ripple. Isnt that basically telling me my alternator is shot?
 
  • Sponsors(?)


trinity_gt

10 Year Member
Jan 31, 2003
3,125
80
99
Canada
When they talk about ripple, they're probably referring to the waveform coming out of alternator. The alternator is really a small 3-phase AC generating station. Three windings in it produce alternating current output that are 120-degrees out of phases. These outputs are fed through a rectifier block and the result is a waveform that has peaks and valleys but which always stays positive. As one phase maxes out and begins to drop in output, the next is rising and when the next one has a greater output than the falling one, the rectifier output follows it. The term "ripple" refers to the difference between the peak and valley voltages at the output of the rectifier. As a simple example of ripple at work, most who've installed aftermarket stereos have heard that annoying whine in the speakers... That whine is caused in part by the ripple nature of the alternator output (and bad grounding...)

Excessive ripple may mean that one winding of the alternator is open or that a rectifier has gone bad. In any event, if the diagnosis is correct, you're probably looking at a new alternator.
 

GDawg

Founding Member
Mar 22, 2002
1,463
19
58
Colorado Springs, CO
Back to life...

Your car wants VDC (volts direct current). Alternators produce a small amount of VAC (volts alternating current) that your computers don't like. There is a diode in the alternator that is supposed to suppress the VAC ripple. No more than .4 vac is acceptable. Once it goes above this you will start to have driveability issues.

I found this thread cause I have that problem and I'm looking at rebuilding the alternator instead of replacing it.
 

stang_ed

New Member
Aug 5, 2009
20
0
1
Back to life...

Your car wants VDC (volts direct current). Alternators produce a small amount of VAC (volts alternating current) that your computers don't like. There is a diode in the alternator that is supposed to suppress the VAC ripple. No more than .4 vac is acceptable. Once it goes above this you will start to have driveability issues.

I found this thread cause I have that problem and I'm looking at rebuilding the alternator instead of replacing it.
Slight correction from an EE. Alternators only create alternating current (AC). The diodes in the alternator rectify the AC to create direct current (DC) needed to power the car and charge the battery. The DC created is not pure and has AC superimposed upon it. The amount of AC on the DC is called the ripple. If one of the windings is bad or if a diode is bad the amount of ripple will be more than normal with the result the effective DC will be low potentially causing malfunction and poor charging of the battery.
 

GDawg

Founding Member
Mar 22, 2002
1,463
19
58
Colorado Springs, CO
Slight correction from an EE. Alternators only create alternating current (AC). The diodes in the alternator rectify the AC to create direct current (DC) needed to power the car and charge the battery. The DC created is not pure and has AC superimposed upon it. The amount of AC on the DC is called the ripple. If one of the windings is bad or if a diode is bad the amount of ripple will be more than normal with the result the effective DC will be low potentially causing malfunction and poor charging of the battery.
Thanks for the insight... I'm still learning... :nice:

What causes a diode to go bad?
 

joshjwc9

Active Member
Jun 12, 2006
1,095
17
39
Palm Harbor, FL
If I am hearing loud speaker whine (as well as cutting out and distortion of the driver tweeter) and I have been for probably a year now, is this caused by an alternator on its way out, or something like bad grounding, a bad amplifier (Mach 460) or a bad battery?
 

stang_ed

New Member
Aug 5, 2009
20
0
1
Thanks for the insight... I'm still learning... :nice:

What causes a diode to go bad?
Semiconductors can go bad without there being a specific external cause. Otherwise, over-current through them and higher than normal temperature can cause failure. Unnatural events such as improper connections (like shorts) can cause failure also. Very high and damaging currents can flow from these causes. Generally, today our auto's charging systems are very rugged and can take a lot of abuse.
 
Thread starter Similar threads Forum Replies Date
ACSPONY Suspension Excess play in rear suspension, springs not staying in place Fox 5.0 Mustang Tech 6
D Excessive shaking during rev up 1965 - 1973 Classic Mustangs -General/Talk- 2
D Excessive sludge found 1965 - 1973 Classic Mustangs -General/Talk- 10
JCBeaver Drivetrain Excessive Vibration at 4K+ RPM while in gears - Any ideas why? 1993 Mustang GT 5.0 with T5 Fox 5.0 Mustang Tech 11
C 98 GT - excessive vapor coming out of one tailpipe in cold temp SN95 4.6L Mustang Tech 1
9 1994 Cobra 331 Dart Supercharged Excessive crankcase Pressure!! Help! 1994 - 1995 Specific Tech 6
W Engine Inconsistent idle and excessive vibration. Fox 5.0 Mustang Tech 17
F Excessive Play In My Steering Wheel Fox 5.0 Mustang Tech 4
rattlecan96gt Modular Headshop/excessive Motorsports 1996 - 2004 SN95 Mustang -General/Talk- 51
7991LXnSHO Allied Nationwide Insurance 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 1
S Fuel Excessive Fuel Pressure 98 Mustang Gt SN95 4.6L Mustang Tech 10
tbear853 How I Removed Excessive Rear Fender Gap .... Pics 2005 - 2009 Specific Tech 1
98blackstallion 320 Lph In Tank Fuel Pump And Stock Regulator? Excessive Flooding? 1996 - 2004 SN95 Mustang -General/Talk- 4
87_LX_5.0 Excessive Toe-in After Brake/suspension Install Fox 5.0 Mustang Tech 12
cdurbin Excessive Heat 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 10
R Forged? 6spd? Preemptive or excessive? 2005 - 2014 S-197 Mustang -General/Talk- 11
92BlackWidowHO Hesitation/excessive Backfiring At High Rpms. Fox 5.0 Mustang Tech 16
Pvt_D Excessive smoke any help? Classic Mustang Specific Tech 1
DeadEnd Excessive Cranking?? 1994 - 1995 Specific Tech 10
9 Ring & pinion excessive backlash Fox 5.0 Mustang Tech 5
MRaburn Excess Ford Mustang stock flattens Ford?s Flat Rock facilities StangNet Site News 0
bgdowski Excessive rich condition Fox 5.0 Mustang Tech 5
M Misfire-Excessive Heat- Melting plastic smell- RPMs stay high after letting off pedal SN95 4.6L Mustang Tech 20
R excessive drivshaft play? Fox 5.0 Mustang Tech 3
R excessive play 2.3L (N/A & Turbo) Tech 3
Platonic Solid Tire Age: Safety Hazard - Excessive Paranoia - or Sales Promo Classic Mustang Specific Tech 29
B Excessive Fuel Pressure Fox 5.0 Mustang Tech 3
SHOJOE Excessive coolant pressure? Fox 5.0 Mustang Tech 12
rayvinton excessive heat on rear brakes SN95 4.6L Mustang Tech 3
grey racer excessive rear brake pad wear 2005 - 2009 Specific Tech 12
9 Piston ring end gap excessive on rebuild Fox 5.0 Mustang Tech 6
DarkoStoj excessive distributor shaft play, msd distributor Fox 5.0 Mustang Tech 2
myponyrocks Excessive shifter movement? SN95 4.6L Mustang Tech 13
hotcobra03 excessive wheel spin =clogged cac SVT Tech Forum 5
XavB excessive bumpsteer with 96 and up spindles Fox 5.0 Mustang Tech 9
deftsound Excessive accessory noise 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 5
Tom95gt excessive wheelhop 1994 - 1995 Specific Tech 8
T 331 Stroker Excessive Crankcase pressure problem 1994 - 1995 Specific Tech 12
T Excessive Crankcase pressure 1994 - 1995 Specific Tech 0
L excessive TV pressure Fox 5.0 Mustang Tech 1
nonglossjason brake floating too excessive Fox 5.0 Mustang Tech 8
R Excessive Play in Steering column after road race practice SN95 4.6L Mustang Tech 4
K overheating and excessive water leaking from exhaust Fox 5.0 Mustang Tech 5
Rickyll7 excessive gear whine GONE after 31 spline swap! SN95 4.6L Mustang Tech 4
grantur01 please help with excessive oil blowing out of motor. Classic Mustang Specific Tech 24
stang730 Will excessive heat kill batt? Fox 5.0 Mustang Tech 2
BlackVert loose header bolt = excessive valve noise? 1994 - 1995 Specific Tech 5
1 Engine Light: EGR Excessive Flow SN95 4.6L Mustang Tech 2
V Excessive Motorsports vs Springfield Motorsports Regional Forums and Event Information 10
S Excessive Blowby? Classic Mustang Specific Tech 10
Similar threads