Alternator?

T

Tech_Greek

Registered User
So, it's buried in my other thread so I figured I would make a new one.

My car has been eating batteries, one cell in particular (the one that's closet to the ground post on the very driver side) - and it's ALWAYS this one.

The voltages are as follows:

Idle, No Lights, No AC, No Radio - 13.0
Idle, A/C, Lights, Radio - 12.5
Idle, Radio, Lights - 12.8

If the alternator is OK then WHY do I keep frying these damn things - the only thing I've done in a while is remove the alarm that was wired into the system.
 
Are you measuring the voltage at the battery during these scenarios? If the alternator is working properly, it should be closer to 14 volts, even with accessories running. The alternator should compensate for a load by increasing output and maintaining charge on the battery. With your numbers dropping into the 12's, id say your alternator, or the main wire between that and the battery, are an issue. Check all connections too!
 
Tech_Greek said:
The voltages are as follows:

Idle, No Lights, No AC, No Radio - 13.0
Idle, A/C, Lights, Radio - 12.5
Idle, Radio, Lights - 12.8

If the alternator is OK then WHY do I keep frying these damn things - the only thing I've done in a while is remove the alarm that was wired into the system.
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Your alternator is gone. Since its voltage is lame, you probaly have a shorted diode.

When you replace it, be sure to fully charge the battery with a charger. Don't use the running alternator for that purpose. You can run it for 10-15 minutes while you're checking things over.

As noted, be sure to clean all the connections well. Use steel wool to clean the oxidation off every connection you can get to related to the battery circuit. Posts, clamps, eyelets, ground straps, etc. You may want to do that before swapping out the alt.
 
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Voltage should read 13.8-14.2 volts reguardless of what is on. Your alternator isnt working. Charge your battery BEFORE you hook up a new alternator,letting your new one charge up a discharged battery is a quick death for your alternator.
 
Alright, I'll buy another alternator - it seems like this battery is about to go dead so I'll just kill two birds with one stone and get a new battery (under warranty) and a new alternator at the same time

I didn't think the voltage output was right, even with the underdrive.

That's with me touch + to + and - to - on the battery off my volt tester.
 
May be Alternator UD Pulley

I don't believe it is the alternator. I believe it is the alternator UD pulley. You said that you took the voltage readings at idle. With UD pulleys, idle is the worst condition especially if you have the AC, lights, etc. on. What is your voltage at around 2000 RPM? Remember, UD pulleys make the alternator turn slower, so at idle Ford designed the OEM alternator pulley to turn the alternator fast enough to produce 13.5 to 14.5 VDC with an average load. When you put a UD pulley on the alternator you are decreasing the alternator efficiency at idle. Again, check the voltage at about 2000 rpm and if you get between 13.5 to 14.5 VDC then get rid of the UD pulleys. I had them on my 94 SC and took them off for the same reasons. Another disadvantage produced by UD pulleys is reduced coolant flow through the motor.

Ed

’94 SC Red Auto: 112,000 Miles, Headers, No Cats, Pro Torque 2500 Stall Converter, TRANSGO Shift Kit, 10,000 Lbs Auxiliary Tranny Cooler, Tranny Fluid Temp Gauge, 3.73 Gears, 70mm BK Throttle Body, 76mm C&L MAF with Gold Tube, A/F Ratio Gauge, Raised SC Top, Teflon IC Seals, ’90 XR7 SC Pulley, ARP Head-Rod-Main Studs, Scorpion 1.73 Roller Rockers, Solid Motor Mounts, Iridium Plugs, Live Wire Plug Wires, Screamin’ Demon Coil, 36# Accel FIs, Custom Air intake, K&N 9” Cone, Royal Purple Synthetic Lubricants and Optima Red Top.
 
I am having similar issues with my UD pulley on the alternator, At cruise it pumps out some nice voltage over 13. But at idle with the lights on and stuff, it starts to use the battery for energy. I run two fans, and its been hot so I think the UD will need to come off on my car. At least for the summer time.

Forget it if I have to turn on the defrost. That bring havoc to the system.
How much power do you think the UD saves from the alternator?
 
MY BAD, I didnt know we were talking underdrive pulleys,reinstall stock pulleys and retest before you spend any money for no reason.
 
garsc said:
MY BAD, I didnt know we were talking underdrive pulleys,reinstall stock pulleys and retest before you spend any money for no reason.
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Nor did I.. garsc is correct. You can test it by speeding up the engine a bit. 1500 RPM should be sufficient... a popsicle stick(s) wedged under the throttle stop should be enough to hold it there while you take measurements. And as noted.. clean all the connections, and charge the batt before you drop anymore $$ into the problem. There are cheap trickle chargers at most retail stores.
 
really make sure the ground to the battery to the body and block are good and the connection from the battery to the alternator on the alternator is good. that could be part of the problem. but yeah clean all connections. my voltage does the same thing. 12 volts at idle then witha little gas im at 14.
 
Finally got it tested out, after getting the charging system to what I felt was up to snuff I figured the battery had already taken a dump on me from the bad terminals thus the reason for it going out.

Well for a change the battery passed and so I upgraded the battery from the silver to the gold (and holy christ does it spin over so fast to start!!!).

But we checked the alt (so they wouldnt void the battery warranty, friend of mine did it) and it passed except for the damn diode.

So apparently it over heated and popped when I had those issues, the only way to fix this is with a new alternator because I'm assuming no one sells these right?
 
Tech_Greek said:
So apparently it over heated and popped when I had those issues, the only way to fix this is with a new alternator because I'm assuming no one sells these right?
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They do sell them, but for the price and effort involved, its easier to just do a warranty trade.
 
"holy-pointless thread batman"

Are you saying that it tested bad and you haven't replaced it???? :confused:

Azone has a lifetime warranty on its rebuilt alts. So if you bought a rebuilt one from there, just take it back. :rolleyes:
 
Meaning whatever one the Previous Owner had on here tested with a bad diode the other day when I posted that.

It looks stock to me and I have not had the money yet to buy a new one - It seems to be working great right now but it's only a matter of time before this one drains out all the way too hehe.

On the machine it said Diode Fail, rest passed with flying colors...the last battery I brought in there did not even fail it had to do with my alternator deciding on when it wanted to charge (it was either that or the old terminals let it get to the point of no return and possibly screwed the diode up from over heating?).

Dunno, I'm going through a divorce right now, I'm going to go ahead and just drive my Galant when I get it back tonight and buy a new one come paycheck.
 
If the diode trio doesnt pass the test the alternator is NFG, period.The diodes convert alternating current to direct current your battery wants to see, probably why it kills batterys.Dont run it till you fix or replace the alternator in fact disconnect the battery till then bad alternators can drain a battery.
 
I'm not woried about the battery it is under warranty (they dont care about replacing it, I know the manager) I've been running it like this for three months now but I'm getting my Galant back in an hour or two so I'll just drive that until I either fix it or sell it...debating on what to do

But for the past few weeks I HAD to get to work some how.
 
Tech_Greek said:
Dunno, I'm going through a divorce right now, I'm going to go ahead and just drive my Galant when I get it back tonight and buy a new one come paycheck.
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Bummer.. A number of people on the for sale forum should have a good used one for a lot less than new/rebuilt. Let me know if you need any referrals. :cool:
 
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