Alternator charging rate
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
At any rate, I run all my diagnostics with a DVM, and if there is one particular fault....I stick a scope on the alt. output stud, looking at the waveform, to check for a bad diode....
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,117
From: Crossville TN
There are many ways to diagnose electrical problems. DVM's, 'scopes, etc. are all good...depending on what you are checking. If accurate signal voltage is not reaching the alternator...for whatever reason...it can't do the job properly. Testing devices with and without a load applied to them is very useful to help in the diagnosis.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Is "voltage" the real issue in overcharging or does the voltage just give us an indication of amperage going into the battery ?
My RV in Florida has a couple of solar cells wired in series on the roof that measure 19.5 volts.
My RV in Florida has a couple of solar cells wired in series on the roof that measure 19.5 volts.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Well, I did and you're FOS, unless all three of my cars are identically farqued up. My GPS unit has a system voltage indicator when plugged in to the cigarette lighter socket, so I simply moved it from car to car just to see.
Each one of the cars behaved EXACTLY as all the others have stated- voltage rose to the high 14s just after starting and slowly decreased to the higher 13s once the battery was recharged. At idle, with all electrical loads turned on, the voltage dropped to the high 12s. Just as expected, just as designed.
Since it's almost Xmas, we won't force you to admit you were wrong, but feel free if the spirit moves you.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Yes, ummm, no. Well yes, sort of. Kinda
To charge a battery, the input voltage must be higher than battery voltage. Amperage won't matter if the voltage is below that.
Once a sufficient voltage level has been established, amperage comes into play. The higher the amperage, the faster the charging will occur.
Within reasonable limits, high voltage by itself won't hurt, nor will higher amperage. High levels of both will cook a battery pretty quickly.
Your solar cells might be producing 19V, but I bet the amperage is so small (probably milliamps) that no damage is done.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
And your right the 19v is measured in MA and after 8 months in the Florida sun the battery tops out at about 12.8 volts.
Instructor
Joined: Jun 2009
Posts: 157
Likes: 1
From: Sebring florida
A 12volt batt is not really a 12v battery. got to Trojen.com, a good golf cart battery mfg, and look up their maintaince specs.
a 100% charged 12 v battery isw 12.73volts
a 75% charged battery is 12.4 volts
a 50% charged battery is 12.0 volts
You cant charge a 12v batt at 12 volts, it must be higher. Normal charge for a running car would be 13.4 to 13.8 and depending on the load it could go up to as much as 14.5 to 15.
If your batt at rest is maintaining less than 12.73 it is showing signs of getting weak, put a load tester on it and see what voltage it maintains and that will give you a better idea of how good or bad it is.
a 100% charged 12 v battery isw 12.73volts
a 75% charged battery is 12.4 volts
a 50% charged battery is 12.0 volts
You cant charge a 12v batt at 12 volts, it must be higher. Normal charge for a running car would be 13.4 to 13.8 and depending on the load it could go up to as much as 14.5 to 15.
If your batt at rest is maintaining less than 12.73 it is showing signs of getting weak, put a load tester on it and see what voltage it maintains and that will give you a better idea of how good or bad it is.
Racer
Joined: Nov 2009
Posts: 289
Likes: 0
From: Franksville Wisconsin
A bad grounding issue, such as the engine to frame, although theoretically possible to cause a bad charging voltage, overvoltage for a while, I would think it's more a connection at the alternator....because the starter cables run negative through the frame in a C3, on my '72 anyway.....
At any rate, I run all my diagnostics with a DVM, and if there is one particular fault....I stick a scope on the alt. output stud, looking at the waveform, to check for a bad diode....
At any rate, I run all my diagnostics with a DVM, and if there is one particular fault....I stick a scope on the alt. output stud, looking at the waveform, to check for a bad diode....
In that case the vette cranked fine but it was grounding issue. Thje strap went from alternator to frame. That did it in that case. It can be many other problems in this case..............
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Melting Slicks
Joined: May 2007
Posts: 3,246
Likes: 4
From: Bay Area CA
Well, I did and you're FOS, unless all three of my cars are identically farqued up. My GPS unit has a system voltage indicator when plugged in to the cigarette lighter socket, so I simply moved it from car to car just to see.
Each one of the cars behaved EXACTLY as all the others have stated- voltage rose to the high 14s just after starting and slowly decreased to the higher 13s once the battery was recharged. At idle, with all electrical loads turned on, the voltage dropped to the high 12s. Just as expected, just as designed.
Since it's almost Xmas, we won't force you to admit you were wrong, but feel free if the spirit moves you.
Each one of the cars behaved EXACTLY as all the others have stated- voltage rose to the high 14s just after starting and slowly decreased to the higher 13s once the battery was recharged. At idle, with all electrical loads turned on, the voltage dropped to the high 12s. Just as expected, just as designed.
Since it's almost Xmas, we won't force you to admit you were wrong, but feel free if the spirit moves you.
I'm not wrong in the context that the question was answered in. that is, if the v-reg causes the alt to put out voltage in the 14's constantly, it will cook the batt. that's true, and that was how i read the post by the OP. Given, some of the posters may know a bit more about Batteries then me, That's good,, but my answer was correct to the question. I'll be sure to point out the finer inconsistencies in your future posts with abbreviated foul language as well. everyones a hero behind a keyboard.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Keep your shirt on. It's almost Xmas. FOS obviously means "Friend of Santa'.
Maybe if you had clarified your initial answer you wouldn't have spent so much energy telling everybody else they were wrong.
Have a nice day, I think you need one.
Maybe if you had clarified your initial answer you wouldn't have spent so much energy telling everybody else they were wrong.
Have a nice day, I think you need one.
Melting Slicks
Joined: May 2007
Posts: 3,246
Likes: 4
From: Bay Area CA
Racer
Joined: Oct 2009
Posts: 441
Likes: 2
From: San Antonio TX
Batteries should be charged first before testing !! by a Battery Charger !
An Alternater is not designed to " Charge " dead or faulty batteries , at least what my electronics training has taught ?
It puts out enough to "Keep" the batteries charged under a load as the system needs.
My experience is mainly in Diesel class 8 Trucks , the alternators I have put on have gone as high as 16+ volts on a 12vt. system
An Alternater is not designed to " Charge " dead or faulty batteries , at least what my electronics training has taught ?
It puts out enough to "Keep" the batteries charged under a load as the system needs.
My experience is mainly in Diesel class 8 Trucks , the alternators I have put on have gone as high as 16+ volts on a 12vt. system
Racer
Joined: Feb 2009
Posts: 427
Likes: 49
From: Pgh. Pa.
Everybody is right and everybody is wrong. Facts and figures are being based on apples and oranges. There seems to be no problem with the system in question. And no harm to the battery will occur. In the early days of the 10SI alt, which is the one in question, The Regs were made with a set point of 14-14.2 volts. Due mainly to the evolution of batteries, changes made in the materials and construction of batteries as well as increased electrical loads Delco changed the set point higher. Todays regs made for 10SI alts have a set point of 14.7-14.8. 14.8 would have been considered overcharge condition if the battery was 25 years or older which I doubt he has. 14.8 is normal for todays batteries and charge system in the 10SI. There is no 1 size fits all as different years makes and models have different set points for voltage. I have been rebuilding and diagnosing charging systems for 35 years. Like I said everybody is right and everybody is wrong depending what data you are basing your diagnosis on. So lets not fight when everyone is right.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
If the voltage is 13.5 to 15.2 the regulator is OK.
If the voltage IS NOT within 13.5 to 15.2 then readjust the voltage regulator to 14.2 to 14.6
My point is the OK range is fairly wide.