Alternator upgrade

[VGMStudios]

Pentalab, DieHarder what are your thoughts?

 

[DieHarder]

Between the two multimeter readings? Can't say which is correct but given others' testing results (like Pentalab) it's best to change out the alternator and retest. If you're going to change it out a later model (2010 Denso) alternator is a good choice. Unless you're running some Godzilla stereo/amps you really don't need a 200 amp. I want to say a standard 130/140 should cover all of your power/charging requirements. If your symptoms change after installation (headlights stop pulsing) I'd retest to see what readings you get on both multimeters and throw away the one that's wrong.

Regardless, if a new alternator doesn't fix the pulsing look at the grounds and lighting circuits. I've had lots of issues w/grounds and my car doesn't have any rust issues per se. If you like I have a DOB alternator (160 amp I believe) that I can take readings from w/my Fluke Multimeter to back up the readings that Pentalab did on his car. I'll post shortly.

 

[Pentalab]

A good DVM, like a Fluke 87 (industry standard) will have what's called dc blocking caps, one per lead ( internally) when trying to read the AC component..while DC is present... IE: meter switched to read ACV. ( DC will not pass through the capacitors). IF the caps are not present, then what happens is the meter will instead read the DCV. IF caps were not present, and you are on the ACV mode, the meter will read 14.75 vdc etc..... but NOT 32 V.

Your yellow meter appears to be reading 32V. But your red meter appears to be reading minimal ACV.

You may well have a lousy grnd connection somewhere...and when you pull current, you end up with a V drop across the shitty connection. Pull more current, and the Vdrop increases.

Assuming the start motor works good, and the battery is good, it's down to either a fried alternator, or bad grnd(S) or both. I can see perhaps one bad grnd connection, but not multiple bad grnd connections.

You might just want to check some of the grnd connections 1st... before buying a new alternator.

If you do find bad grnd connections, they have to be repaired, and perhaps some permatex dielectric grease on the connection, to keep moisture out.

 

[VGMStudios]

Alright I'll check my grounds for sure just to make sure they are okay and will add the dielectric grease.
But what I am most interested in is when I tested my mom's car the yellow one read the same thing, 32v. So I don't know if I can trust that and I don't have a Fluke. They are crazy expensive. Maybe I'll see if I can borrow one from someone.
My battery is good and the start motor is good too.
Thank again pentalab and DieHarder for the feedback. I'll keep you updated.

 

[DieHarder]

If you want to eliminate the ground issue run a fairly good size stranded cable (04 gauge with lugs) from the passenger strut tower ground and connect it (via a lug) to a mounting bolt for the alternator. You can pick up cabling/lugs of this size at HD/Lowes (take ground bolts to be sure the lug holes are the right size). I had to add a ground wire on mine which fixed all of my charging issues. I still have a bad ground somewhere but routed around it by adding another. Not that I'm advocating for band-aids mind you but rather it's a good troubleshooting step to eliminate it as a problem.

 

[VGMStudios]

Just wanted to update on my situation.
I finally was able to get the 2010 alternator and it wiped out all my issues. I did have a parasitic draw at first but it fixed itself after trying a few things. So all is well now in regards to this issue.
Thank you everyone for all the help.

 

[Pentalab]

Excellent. I checked, and the oem alternator in my 2010 GT is rated at 135 amps. Meanwhile, the alternator in my 2011 Ford Fusion is rated at 160 amps.

 

[VGMStudios]

Really? How odd. The one I bought was rated at 150 amps. The car feels more powerful now. Haha. Probably a placebo effect. I'm just glad it's working again.

 

[Juice]

Really? How odd. The one I bought was rated at 150 amps. The car feels more powerful now. Haha. Probably a placebo effect. I'm just glad it's working again.

Very possible the car IS running better, now that you have a steady 14.x volts.

 

[Suecra]

usually flickering is fine when its momentary, the alternator and entire drivetrain has to catch up to any sudden demands like the fan kicking on for the cooling system, the a/c engaging, and so on. Alternators on most cars do not need to be upgraded, the extra amperage cannot simply be directed by choice, and usually a better battery, or incorporating a capacitor somewhere can help if there is an actual issue, but an actual issue should also simply be fixed if possible first.