HYPR
Ultra Senior Member
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 12-01-21 12:58 PM - Post#2831689
I'm having a charging problem in my '56 210. I have a MSD 5111 160AMP alternator and have had it checked. The unit is functioning properly producing 14.5V under load. I already have the smaller pulley installed. I have a newer Optima Yellow top installed Charged and measures 100%. I also am using a Painless remote starter relay. I have installed a new Moroso battery cut off switch. The positive and ground lead to the engine bay are both fine wire 1/0 gauge and I have several grounding leads to the frame and one to the engine block. The Alternator leads are all >12gauge. The leads from the battery cut off switch are 1/0 gauge and the main line to the accessory wiring blocks is 4 AWG. The Stereo Amp is powered by 8AWG. I have attached photos of the wiring. BTW once the Stereo Amp is charged even if the Cutoff Switch is in the off position it still shows it has 12volts at the Fuse block. All other Wiring block locations show less than 1 volt with the AMP fuse connected. When that fuse is disconnected all points show 0volts when measured with the Battery cut off switch is in the off position. When the switch is in the on position all points measure >12volts.
When idling the voltage at the alternator measures 12.5-12.76volts. At about 2000RPM the output measures no more than 13.5Volts. My concern is after a period of time the battery gets drained and then the Alternator outputs under the same conditions measures only about 12.3-12.5volts and never recovers back up to the >13.5volts charging rate.
Does anyone have a suggestion or opinion on the cause of the problem?
Edited by HYPR on 12-02-21 11:20 PM. Reason for edit: No reason given.
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 Shepherd
Valued Contributor
Posts: 3507
Loc: Lake George, NY
Reg: 11-11-15
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12-01-21 02:33 PM - Post#2831691
In response to HYPR
Just a suggestio, the alternator output under load should be checked with an ammeter, normally as the amp output increases there is some drop in voltage, the amount varies from system to system.
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HYPR
Ultra Senior Member
Posts: 10809
Age: 72
Loc: Shaking and Burning!
Reg: 07-19-01
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12-01-21 03:55 PM - Post#2831697
In response to Shepherd
Just a suggestion, the alternator output under load should be checked with an ammeter, normally as the amp output increases there is some drop in voltage, the amount varies from system to system.
Thanks, I searched to see if I have a set of Alligator clips for this purpose but can't find them LOL so I ordered a set.
Anyway, what will this test show me other than if the Alternator is not producing enough Amperage. Other than installing a PWM Generator I am not sure what I can do. Unfortunately the only PWM I have seen are for two pin Alternators and mine is a one wire version.
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Shepherd
Valued Contributor
Posts: 3507
Loc: Lake George, NY
Reg: 11-11-15
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12-01-21 06:41 PM - Post#2831706
In response to HYPR
You can get a ammeter that slips over the battery cable or single wire on the alternator, this is accurate enough to load up the electrical system and read the alternator out put.
Ht hps://www.jbtools.com/sg-tool-aid-24600-600 -amp-al...
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HYPR
Ultra Senior Member
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Age: 72
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Reg: 07-19-01
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12-02-21 09:31 PM - Post#2831785
In response to Shepherd
Thank you for your reply and yes I have done all that. I even spent time to rerun the lights power directly to the battery junction blocks to be sure the HID headlights are not a contributing factor. See the photo above of the Painless Starter Relay. The terminal on the left is the 1/0 Negative lead which runs uninterrupted to the Negative pole of the battery. There is a junction block in the trunk that has a number of leads to the frame and then one to the Negative pole on the battery and one directly to the audio. Additionally as already mentioned the frame is also grounded to the engine block.
Next see the leads to the Started (smaller posts), Next see the two leads on the right. The 1/0 lead runs directly to the Moroso battery cut off switch (brand new), The other is the Alternator lead 2/0. This is were I am picking up my Battery Positive.
Next test at the battery with the MSD switch on and Ignition off, all Positive Junction points measure exactly the same 13.15 - 13.5 volts depending on when the test was done. NOW COMES THE PROBLEM as I see it. After turning the switch off and even with ALL the Fuses which you see at the junction blocks in the photos above) every Positive point measures 1.11 volts. I then waited about 3 hours and repeated the test and all points measured .30 volts. I then turned the Moroso battery cut off switch on and measured 13.5 volts. I then turned it off and I measured at the Positive lead that runs up the frame rail and 0 Volts. Then I measured all the same Junction block points and once again 1.11 volts. How is it possible that a switch is storing energy? The lead to the Ignition is indeed interrupted however all the other points still show energy. My assumption is that the Moroso battery cut off switch may be drawing voltage. Any thoughts?
Edited by HYPR on 12-02-21 11:22 PM. Reason for edit: No reason given.
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CowboyTrukr
"13th Year" Silver Supporting Member
Posts: 4899
Loc: Salt Lake City
Reg: 06-20-09
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12-03-21 08:55 AM - Post#2831807
In response to HYPR
There is the concept of stored voltage in an insulated cable that is deenergized but not grounded. Capacitive charge usually isn’t a big deal.
Help me understand the concept of switching in your negative cable, please? Or, at least how you have the remote solenoid wired?
From what you’re describing, I see a dead short happening across that solenoid when you turn on the switch. From all the vehicles I’ve seen through the years, the aux relays always switch the hot lead on and off. Obviously that’s not happening, so am I misunderstanding what you wrote?
Greg
‘21 Silverado 1500 4x4 5.3 - ‘17 Journey
‘01 2500HD 8.1/Allison 1000 Xcab/LB SOLD
“Bad men need nothing more to compass their ends, than that good men should look on and do nothing.” - John Stewart Mill |
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bobb
Super Senior Member
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Loc: paradise
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12-05-21 11:33 AM - Post#2831953
In response to HYPR
as i recall the msd alternator needs rpm to charge. stereo and igntion module may be storing energy. if there is no problem with battery going dead i wouldnt worry about it.
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TjK
Newbie
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Age: 39
Loc: Sweden
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01-26-22 04:44 AM - Post#2835246
In response to HYPR
Hi
I used to have big charging problem at idle, ive got 12-12.5 at idle.
There where alots of different answers but no one could fix the problem. At the end i called a alternator firm and stated my problem and the guy said that most alternators dont charge under 2000-2500rpm
So ive got me a 7.7" pully on the engine and a 2" on the alternator and BAAM the car never goes under 13.6 even with heavy amps installed.
You said you changed to a smaller pully, what size is that and what size is the crank pully?
My alternator spins at 3500rpm at idle.
7.7" (196mm) / 2" (52mm) x 950rpm idle = 3580rpm
If you let say also has 2" but smaller crank maybe that is the problem, let say you have a 6" and idle at 600-700rpm
Your alternator idle is 1800-2100rpm
This is my thoughts about it.
Maybe it helps ????
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Tony1963
Frequent Contributor
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Loc: Orlando Florida
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01-26-22 08:07 AM - Post#2835251
In response to TjK
Someone who tells you that most alternators don't charge at idle speed is simply NONSENSE.
Granted that below a certain RPM, charging will be limited but at idle, you should get charging voltage.
Using a smaller pulley makes the alternator spin faster.
| People fear change because it threatens what they know, or what they claim to know. |
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65_Impala
Very Senior Member
Posts: 5038
Reg: 12-29-02
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01-26-22 12:18 PM - Post#2835264
In response to Tony1963
It's not like it's a on-off switch, but below 2000 alternator rpm, not crank rpm, the output of most alternators drops off substantially. Here is 10SI alternator curves. Below 2000 alternator rpm, a 72A alternator drops to <20A output. That won't run much. The 63A alternator is better at 30A, but still not great.
Something to also be careful about is the alternator maximum rpm. I would stick to the 15,000 to 18,000rpm range as the maximum. Using 7.7" crank and 2" alternator pulleys limits the engine to about 4600rpm. Run that engine to 5500-6000rpm once too often and the alternator could explode.
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Tony1963
Frequent Contributor
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Loc: Orlando Florida
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01-26-22 05:32 PM - Post#2835278
In response to 65_Impala
2000 RPM on the alternator is about 500 RPM on the engine. I will agree and stipulate for the record that an engine in a modern car turning at less than 500 RPM will not put out sufficient voltage to charge the battery.
| People fear change because it threatens what they know, or what they claim to know. |
Edited by Mercedes on 01-26-22 05:33 PM. Reason for edit: No reason given.
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65_Impala
Very Senior Member
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Reg: 12-29-02
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01-26-22 07:16 PM - Post#2835286
In response to Tony1963
You can make up whatever numbers you want, but pulley ratio is typically closer to 3:1 then 4:1. Alternators typically spin around 2000rpm at 650-750rpm engine idle.
The most important design change on newer model alternators is boosting the idle output. The 140A CS144 will produce 95A or 67% of it's rated output at idle. A 72A 10SI only produces 28% of it's rated output at idle.
a 4:1 alternator pulley ratio will over-rev the alternator at maximum engine rpm on pretty much every GM gasoline vehicle engine that has been produced in the last 60+ years.
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TjK
Newbie
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Age: 39
Loc: Sweden
Reg: 09-20-21
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01-26-22 07:41 PM - Post#2835287
In response to Tony1963
Yes is correct, it does charge but leaving 12-12.5v when your are in a cruising, the stereo is playing and lights are on and there you stand with a dead battery.
So a smaller wheel made get 13.6v standing in a cruising.
I normally drives around 2800rpm-3000rpm on the freeway and that is around 11500rpm on the alternator so I feel safe. It's and 240amp alternator and used this setup for 4 years now. Works great.
But if I whant to go Bang and drive 5500rpm on the strip yeah the alt would prob go bye bye
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65_Impala
Very Senior Member
Posts: 5038
Reg: 12-29-02
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01-26-22 08:41 PM - Post#2835289
In response to TjK
I'm curious where you got your 240A alternator and what the heck are your running for load? That rating should have been producing way over 100A at idle before your pulley change.
I'm running an old stock CS144 with the factory pulley ratios and it's maintains 13.9-14V when at idle with the lights, cooling fan and 500W of stereo running.
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japete92
Frequent Contributor
Posts: 2306
Loc: No. Virginia
Reg: 01-18-13
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01-27-22 07:00 AM - Post#2835303
In response to 65_Impala
You can make up whatever numbers you want, but pulley ratio is typically closer to 3:1 then 4:1. Alternators typically spin around 2000rpm at 650-750rpm engine idle.
The most important design change on newer model alternators is boosting the idle output. The 140A CS144 will produce 95A or 67% of it's rated output at idle. A 72A 10SI only produces 28% of it's rated output at idle.
a 4:1 alternator pulley ratio will over-rev the alternator at maximum engine rpm on pretty much every GM gasoline vehicle engine that has been produced in the last 60+ years.
That's been my experience.
I'll ask some questions to not be offensive:
Does not the alternator's output CURRENT (amps) charge the battery and run all the electrical devises; and varies with the rpm?
Is not the VOLTAGE relatively constant via the regulator (internal or external)?
The 'stipulation' that the voltage will be too low at idle to charge the battery is erroneous.
240 amp alternator? WOW.
Pete
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TjK
Newbie
Posts: 19
Age: 39
Loc: Sweden
Reg: 09-20-21
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01-27-22 11:28 AM - Post#2835309
In response to 65_Impala
Hey, it is a Power master alternator, I did never measure the load back then, my Eyes only saw the volt meter goes from driving 13.6v-14v to red lights and drop.
But have 2 viair compressors that goes quit often and have 3 Ground zero 1850DXII amps that EATS crazy amount of power to support 12 6.5" speakers and 2 12" speakers.
Other then that, nothing.
Only different from then anf now is that my volt meter never drops any more. And I got 3 180amp battery in the trunk.
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65_Impala
Very Senior Member
Posts: 5038
Reg: 12-29-02
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01-27-22 11:29 AM - Post#2835310
In response to japete92
That's been my experience.
I'll ask some questions to not be offensive:
Does not the alternator's output CURRENT (amps) charge the battery and run all the electrical devises; and varies with the rpm?
Is not the VOLTAGE relatively constant via the regulator (internal or external)?
The 'stipulation' that the voltage will be too low at idle to charge the battery is erroneous.
240 amp alternator? WOW.
Pete
To put it in simplistic terms. The alternator tries to produce something like 14.2V at the output terminal. The alternator can only output so much current though. If the car requires more current than the alternator can supply, then the alternator output voltage starts to drop until the current balances. More or less the car demand goes down and/or the battery begins to supply the car instead of the alternator when the alternator output voltage goes down.
Of course, there is some more complexity. The alternator has a remote voltage sensing terminal. The regulator varies the regulated voltage based on temperature.
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Tony1963
Frequent Contributor
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Loc: Orlando Florida
Reg: 07-09-18
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01-27-22 12:34 PM - Post#2835312
In response to 65_Impala
"about 500 RPM", okay then, closer to 650 RPM.
Nonetheless, you should be getting adequate charge out of the alternator. By mentioning voltage, I am assuming that someone is taking a voltage reading at the battery at idle, the end result of all of the amps and spinning parts.
If you are not getting above 12.5 volts, then you are not charging the battery. However, even on my 62 and 64s, they put out adequate charge at the battery at idle around 550 RPM.
Now, turn on the headlights, run the fan on high and turn on every other accessory, probably won't cut it for long.
| People fear change because it threatens what they know, or what they claim to know. |
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65_Impala
Very Senior Member
Posts: 5038
Reg: 12-29-02
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01-27-22 12:43 PM - Post#2835313
In response to Tony1963
Now, turn on the headlights, run the fan on high and turn on every other accessory, probably won't cut it for long.
 That'd be because it is not charging, it's not even enough output to maintain the current battery charge level. Didn't you say that an alternator not charging at idle is nonsense?
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Tony1963
Frequent Contributor
Posts: 2448
Loc: Orlando Florida
Reg: 07-09-18
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01-27-22 01:35 PM - Post#2835314
In response to 65_Impala
I did. And you are taking my words out of context.
To suggest that no alternator charges at idle I called that NONSENSE.
Is it possible to exceed the demand of the alternator at idle? YES
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