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I'm one of the blessed souls that have chronic low voltage. As of now, the car has the factory alternator which does an ok job of charging and running accessories as it's supposed to, but the voltage isn't really as it should be. It's tough to justify changing an alternator that works, especially since its in the stock location.... and the way the driver side manifold comes across it, makes it a nightmare to change. So the question is, has any of you
had the same issue...changed to the H.O truck alternator and seen any noticeable and consistant increase in performance?
I did. Not necessarily forced induction just meek little boltons. Did bigger battery cables and a $60 KG3 from a pull-a-part. Car seems to respond quicker to all inputs or it could just be a placebo. Pretty easy to install too. Unbolt sway-bar from driver's side (if it's still there), bend the powersteering lines to your liking, and it should rock right in. I would take some sandpaper to both the inside of the alt bracket where the bolts pass through and where they make contact on the alt itself. Mine required a little coercing with a rubber mallet but nothing silly. Can't get it to drop below 13.5 no matter what I do.
I tried a truck alternator and mine stayed the same. My needle was at the same place yours is. What's weird is at the alternator it's around 13.2-13.3 and at the fuse box 13.0 and needle shows like 12.7. When I first start it, it charges 13.7 then goes down as the engine warms up. Another member here swapped to the 160 amp eBay alternator and said it fixed the low voltage.
Hi my first observation is as stated above, measure V-BAT then check for your gauge read.
The CAN information for correct gauge operation may not be correct.
The second PROBLEM with HIGH ALT RPM is that this can DESTROY the ALT.
I would slow down the ALT Speed if your Engine RPM is greater than 6600 IN ANY CASE.
This is an easy fix when a larger pulley is fitted.
I did. Not necessarily forced induction just meek little boltons. Did bigger battery cables and a $60 KG3 from a pull-a-part. Car seems to respond quicker to all inputs or it could just be a placebo. Pretty easy to install too. Unbolt sway-bar from driver's side (if it's still there), bend the powersteering lines to your liking, and it should rock right in. I would take some sandpaper to both the inside of the alt bracket where the bolts pass through and where they make contact on the alt itself. Mine required a little coercing with a rubber mallet but nothing silly. Can't get it to drop below 13.5 no matter what I do.
Good stuff, I've got the big cables... just lacking the alternator.
Originally Posted by laytoncamaroz28
I tried a truck alternator and mine stayed the same. My needle was at the same place yours is. What's weird is at the alternator it's around 13.2-13.3 and at the fuse box 13.0 and needle shows like 12.7. When I first start it, it charges 13.7 then goes down as the engine warms up. Another member here swapped to the 160 amp eBay alternator and said it fixed the low voltage.
This is EXACTLY what mine does, when cold....gauge shows on the high side of 13.
Originally Posted by Pantera EFI
Hi my first observation is as stated above, measure V-BAT then check for your gauge read.
The CAN information for correct gauge operation may not be correct.
The second PROBLEM with HIGH ALT RPM is that this can DESTROY the ALT.
I would slow down the ALT Speed if your Engine RPM is greater than 6600 IN ANY CASE.
This is an easy fix when a larger pulley is fitted.
What is your ALT RPM at 6600 Engine RPM ?
Lance
Not sure what the alternator speed is, but I typically shift around 6300....sometimes by accident 6800 (traction).
Redoing battery wiring, terminal connections and grounds can make a noticeable improvement in electrical performance. Larger wiring, cleaner grounds with anti oxidation paste.
Anything to make the electrons travel easier is a good thing.
Hi, the measurement of V-BAT reduction when your car "sits" overnight or longer WILL find a lower battery charge.
Check the Battery Voltage BEFORE start-up.
You will find the current needed to keep the On Board Electronics "alive" will lower that voltage, overnight or longer.
When the ALT controller "sees" this the Charge Voltage will be HIGHER.
Thus CORRECT operation is noted with the voltage DROPPING as the battery reaches FULL charge.
I have the same problem, im pretty sure that i have some resistance somewhere. I dont think the alt output is the problem. Im going to change my ignition switch one day and see if that helps.
I agree but some days my windows are slow and my radio is slightly dim when turned up. I have a aftermarket radio but no extra amps or add ons to electrical system.
I agree but some days my windows are slow and my radio is slightly dim when turned up. I have a aftermarket radio but no extra amps or add ons to electrical system.
Another good thing to do is run say a 4ga wire from the rear alternator case to a clean engine ground. Alt produce a/c current and the rectifier inside chops this up into dc current. Sending the positive side to the charge lug and the ground side gets passed on through the case. If you look, the rear case doesn't touch anything, it mounts on the front half and only has 4 little bolts holding it together
There are some good videos on YouTube about doing the Big 4 upgrades
I've added this wire and after some maintenance forgot to rebolt the wire to my engine plate. After a days worth of racing, my ground lug had arc welded itself to the plate. So some amperage was passing though it
Usually people forget to upgrade the alt pigtail when changing the alt. actually looking at how small the wire is would tell you why. its bent in a very bad position and can cause issues. Using alot larger cable from batt to alt and from batt to bldy and engine to either batt or body helps out tremendously. Even from batt to accy fuse panel helps. The stock wiring is very anemic.
Every truck alt upgrade we have done get a new hd pigtail. Even the reg drop in powermasters etc get the same.
different car but on my c6 the car is much better with billetech fancy 240amp alternator. the fuel injectors and coil dwell are all scaled on voltage too so I don't think placebo. even idles a tiny bit smoother and just seems more responsive. hard to explain but car just feels happier all the time.
It matters way more in a vette where voltage and proper grounds matter more, but uses same concept. more power avail is more power to use esp at high rpms.
I've had good results from just taking the grounds off under the hood and sanding off the paint to get a clean connection. Not a hp gain, but a less lights flickering stuff runs better thing
One time i put 2 alternators on a VR6, both new, both wouldnt charge. Come to find out, the mounting bracket was powder coated and the Alt couldnt ground.
Adding a ground from the case of the alt may help and really easy to test/install.
All good ideas. May even help with the sometimes hard cold starts, I've been attributing it due to the poor burn of E85 and a cold motor... Who knows. But checking grounds is easy.. and cheap enough.
Sometimes its just the alternator.
I bought an O'Reilly's reman special and it was in the same spot for about a year then crapped out.
I upgraded to the fully new unit for few more bucks and now it operates as it should cycling between battery voltage and 13.5 volts.
Currently running dual Derail fans, stereo amp, oil cooler fan and dual fuel pumps and so far so good lol.
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Gains from increased voltage? 
