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Alternator voltage

nvrenuf

nvrenuf

Holy crap, it's running!
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I finally finished my wiring project and cranked the Blazer today. :woot:

My charging voltage seems a little high at 14.2-14.3v (running @ idle), this reading is the same on both an Autometer gauge and a digital read out on a USB port I added. Is this acceptable for a (stock) CS130 alternator?

The battery has been on a tender for a while so it should be charged up and not needing extra help.
 
That’s about what mine is at even with the battery on a tender and it’s just a stock voltage alternator. It’s fun to watch it dance with the subs though.
 
I kinda had a feeling that it was close to normal. Fingers crossed.
 
I have a couple of CS130s that will run 14.5 to 14.6 with no load. Never had a problem. You don't want it to push 15 or higher from what I understand, the battery won't like it long term.
 
Mine runs "high" too...the only thing that will really bring it down is the crappy tailgate motor being stalled. I've measured pretty much everywhere on the truck and it's consistent.

I'm a bit suspicious that maybe this is a bit harder on the battery than it should be. My understanding is that the voltage should drop as the battery is charged. That never happens.
 
Most CS130 regulators are set at 14.6 to 14.8 volts. Some have temperature compensation built in, so they will run higher at cool alternator temps, and then turn the voltage down, as the temps come up which is exactly what the battery wants. The Dodge/ Jeep computer systems, will very as much as 2 volts, between hot, and cold. 13.6 volts, to 15.6 volts. At 14.2 volts, you will be just fine!
 
Feeling much better now, I was afraid something with all the new wiring and harness might be a problem. Thanks everyone!
 
Wait until you run into one of the modern auto charging systems.
I've got a digital voltmeter that plugs into the power port. It monitors the car's voltage, and has two USB ports. When you plug anything into the USB port, it switches back and forth between the car voltage and the USB current so you can see how much your device is drawing.
Driving down the road not long after I got the car new, I glanced down at the meter and it read 12.5V. Really ticked me off. A brand new car, and the alternator has gone out.
Funny though, no warning lights or check engine light.......
I knew it had a big AGM battery, so I just kept rolling. Figured I would take it into the dealer the next morning. About an hour later, the voltage was back to 14.5.
I did some research. Turns out the alternator voltage output is computer controlled by the main system. It has a charging algorithm that adjusts the charging voltage according to a range of parameters to try and maximize battery life and fuel economy.
Under certain circumstances, it turns off the alternator completely.
Since it turned it off, there are no warning lights or trouble codes set. Still a little unexpected to see it not charging.

Funny thing, last time I took the car in for service, they told me I needed a four wheel alignment and a new battery. Said the computer had detected some problems with the battery and they recommended replacement just in case. Only $240. I asked what it had detected, and he did not know. But he said it monitored charging voltage, current, plus cranking voltage and current, and something had been out of parameters.
I reminded him that it was an AGM battery, and I expected to get at least 5-7 years out of one of those. Instead of the two I had had it.
He told me that since the car had the auto-stop feature where it stopped the engine at red lights and stop signs then restarted it when I released the brake, that constant recranking stressed the battery and it was a good idea to replace it early.
I informed him that in the two years I had owned that car, it had had to restart about 4 times. That was how many times I got distracted when starting the car and forgot to hit the lockout button.
I did not replace the battery.
I also drove it on my friend's top of the line Hunter alignment rack the next day and it was dead on.

I guess they just recommend these things automatically when the car reaches a certain mileage. I am a little disappointed. Its the first time since I bought the car there that they have tried something like this.
They did use to recommend a battery terminal treatment and a alcohol based fuel system cleaner every time I got it serviced.
But I shut that down early, and my service guy never suggests them any more. He was out sick, and I think the new guy figured me for an easy mark.
 
Honda started that crap back in the late 80's. Electronic load detection, alternator field report, alternator computer control. Would turn the alternator off completely, if certain parameters were met. Over built, under designed. BS! GM used this crap in the mid 2000's, on their full size trucks, and suv's. Also, didn't last long. Thank God. Ford used a different approach. Half alternator control, and half computer control. Base voltage set by alternator regulator, and computer controlled voltage set by a digital pulse width modulated signal. Very hard to diagnose which one is at fault. Dodge uses a completely computer controlled charging system, with no smarts in the alternator at all. Works very well. Then around the mid 2000's, on their Cummins trucks, Dodge decided to move the alternator charge wire from the drivers side battery, to the passenger side battery. The computer looks at battery voltage from the drivers side battery. The two batteries are connected by a large battery cable. What could possibly go wrong? The passenger side battery positive cable attaches to the drivers side battery cable clamp bolt. The bolt loses connection in the lead clamp. The drivers side battery drops down to battery voltage. The computer cranks the alternator wide open, therefore boiling the passenger battery, until it explodes, coating the entire engine compartment with battery acid! I had a customer with a quote of $10,500 damage to his engine compartment and exterior paint, caused by battery acid. It even blew back, and ate the paint on his dually fender! I have a new charge wire setup, for these trucks, if any of you guys own one. It will stop the damage, before it happens!
 
500$k5 said:
Honda started that crap back in the late 80's. Electronic load detection, alternator field report, alternator computer control. Would turn the alternator off completely, if certain parameters were met. Over built, under designed. BS! GM used this crap in the mid 2000's, on their full size trucks, and suv's. Also, didn't last long. Thank God. Ford used a different approach. Half alternator control, and half computer control. Base voltage set by alternator regulator, and computer controlled voltage set by a digital pulse width modulated signal. Very hard to diagnose which one is at fault. Dodge uses a completely computer controlled charging system, with no smarts in the alternator at all. Works very well. Then around the mid 2000's, on their Cummins trucks, Dodge decided to move the alternator charge wire from the drivers side battery, to the passenger side battery. The computer looks at battery voltage from the drivers side battery. The two batteries are connected by a large battery cable. What could possibly go wrong? The passenger side battery positive cable attaches to the drivers side battery cable clamp bolt. The bolt loses connection in the lead clamp. The drivers side battery drops down to battery voltage. The computer cranks the alternator wide open, therefore boiling the passenger battery, until it explodes, coating the entire engine compartment with battery acid! I had a customer with a quote of $10,500 damage to his engine compartment and exterior paint, caused by battery acid. It even blew back, and ate the paint on his dually fender! I have a new charge wire setup, for these trucks, if any of you guys own one. It will stop the damage, before it happens!
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Is this why on my 05 Tahoe the volt gauge drops to 12ish then back up to 14 randomly? I replaced the Engine so I know all cables are tight and it also did this before.
 
Babaganoosh said:
Is this why on my 05 Tahoe the volt gauge drops to 12ish then back up to 14 randomly? I replaced the Engine so I know all cables are tight and it also did this before.
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I believe an 05 has that system. Probably normal. When it does it, reach over and hit the Tow/Haul button on the shifter. If it's working normal, the voltage will go up in Towing mode.
 
500$k5 said:
I believe an 05 has that system. Probably normal. When it does it, reach over and hit the Tow/Haul button on the shifter. If it's working normal, the voltage will go up in Towing mode.
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I'll have to give it a try, honestly it starts everyday so I didn't care. :rotfl:
 
500$k5 said:
Honda started that crap back in the late 80's. Electronic load detection, alternator field report, alternator computer control. Would turn the alternator off completely, if certain parameters were met.
Click to expand...

What hondas did that? They just throw a battery light if parameters not met. until the 2010's or so.
 
fordsucks! said:
What hondas did that? They just throw a battery light if parameters not met. until the 2010's or so. They started this system in 1988, and thankfully trashed it a few years after. 88 to 95 Civic, 90-93 Accords, 92-96 Preludes, quite a few Accura's, etc.
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Mine is a 2019 Passport, and it definitely has some kind of computerized charging strategy.
 
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