power distribution conundrum

[Mountain Gnome]

So today I hooked up both meters at the same time. The graphing meter has two channels.


I hooked the Crafstman to the alternator post on the isolator, and the graphing meter to the battery posts on the isolator.


Then I tested. Here is the results:
https://youtu.be/JTnmsU5lDYI


Attached is simple pics of the meters connecting to the isolator, and the voltage reading before starting the motor. Note I just charged all batteries, yet they show a bit low. They sit around not being charged too much....

[TJones]

I dont think that the modifications you found are necessary for your isolater. I am thinking that maybe the isolater is isolating not just battery #1 from battery #2 but also isolating the alternator from battery #1.

Is there any voltage at the alternator (+) post when ignition is off or on ?

If not try connecting the battery #1 (+) lead to the alternator (+) post on you isolator. This should still isolate battery #2 while giving the alternator voltage to operate.

Ted

[Mountain Gnome]

Originally Posted by TJones

I am thinking that maybe the isolater is isolating not just battery #1 from battery #2 but also isolating the alternator from battery #1.

Um....what? Can you not see the voltage rise for batt #1 when the alternator kicks on?



The confusing part to me is that the battery voltage is greater that the alternator voltage in some instances...

Originally Posted by TJones

Is there any voltage at the alternator (+) post when ignition is off or on ?

As mentioned:


IGN wire (a.k.a. exciter wire) connected to isolator:
key off: ~0.3V
key on: ~7V (varies)


IGN wire (a.k.a. exciter wire) not connected to isolator:

key off: ~0.3V
key on: ~0.3V

Originally Posted by TJones

If not try connecting the battery #1 (+) lead to the alternator (+) post on you isolator. This should still isolate battery #2 while giving the alternator voltage to operate.

That would allow #1 to drain into #2.

[Mountain Gnome]

So this time I bypassed the isolator, using just the starter batteries, and ran another voltage test.


https://youtu.be/3dEJEb3Q1YI


We see at about 0:47 in the video, as I turn on the second AC system, the volts drop to under 13V, when the motor is idling. Revv it up, and the voltage increases.


So the rebuilt ProAmp alternator is weak at idle. Not made for a school bus, but rather an OTR truck.


More to come.....

[Mountain Gnome]

I wanted to see how the alternator responds when it is spinning faster than idle and the AC is turned on, using the battery isolator. So here is that test:


https://youtu.be/QmFyis6OdNQ


It still fails. All this leads me to believe that, yes, it does need that voltage regulator "sense" wire (the "S" connector that is supposed to be on the back of the alternator). Not even to consider that the instructions say it does.


So now that is what I'm gonna do. Take the alternator out, take it apart, cut the internal voltage sensing wire, and add a lead to the outside of the case.


My logical explanation of what is happening is that when the AC is turned on, it surges and draws all the power that the alternator is producing, dropping the voltage below what the voltage regulator can work with; so it does not up the voltage back to what it should be. When the battery is connected directly to the alternator (+) terminal, the surge is buffered by the amps in the battery. Plus, the sense wire will be restored to battery voltage after the surge, so the regulator keeps on working. Or sumt'n' like that.


More to come...

[TJones]

I thought you were not getting any charge from the alternator with the isolater installed. Looks like its working OK other than low voltage at idle but that is not uncommon especially if the load of the A/C is on. Alternators do not produce much current at idle rpms.

Ted

[Mountain Gnome]

With this test, I have the AC turned on before I start the motor. Battery isolator connected with the IGN (exciter) wire connected, as the test just previous.


https://youtu.be/NjEOU9-PqQc

[Mountain Gnome]

Originally Posted by TJones

I thought you were not getting any charge from the alternator with the isolater installed. Looks like its working OK other than low voltage at idle but that is not uncommon especially if the load of the A/C is on. Alternators do not produce much current at idle rpms.

Ted

You know at this point, I'm loosing track of what the original tests were doing. And I was only using one voltmeter at a time, and was under the vehicle while testing.


That is why I'm doing the tests all over, with three individual meters running simultaneously, and video recording it all. I watch the video, and see things I missed when I was testing. And I have a solid record of what I found, instead of going by memory.


What I'm not seeing in these videos is ~3V at the alternator post and ~13+V and ~14+V at the battery terminals, like I originally saw, which blew my mind. I'm trying to recreate that...what exactly was the procedure I did before.

[john61ct]

I'm not following the details here much, so forgive if this is off base.

I would make sure that all load devices can run effectively for long periods of time without any input from the alternator, just off stored energy from the House bank.

Then, keep the load devices turned off, and do all the alternator testing with a 50% depleted House bank, so the only demands for current come from recharging those cells.

Having the Alternator in effect servicing loads directly IMO is a bit too complex and unpredictable, too many variables involved.

Later, as a second stage, if the bank is too small to draw a decent current from the alternator, devise slowly increasing loads, say in 10A increments.

Very few alternators, even brand new top quality units correctly installed, can output anywhere near their rated output for more than a very short time.

Special voltage regulators or B2B DCDC chargers are usually needed to throttle current output

in order to maintain the correct charging voltage setpoint, and keep overtemp conditions from halting proper charge output or burning up the electronics.

[Mountain Gnome]

Originally Posted by john61ct

I'm not following the details here much, so forgive if this is off base.

I would make sure that all load devices can run effectively for long periods of time without any input from the alternator, just off stored energy from the House bank.

Then, keep the load devices turned off, and do all the alternator testing with a 50% depleted House bank, so the only demands for current come from recharging those cells.

Having the Alternator in effect servicing loads directly IMO is a bit too complex and unpredictable, too many variables involved.

Later, as a second stage, if the bank is too small to draw a decent current from the alternator, devise slowly increasing loads, say in 10A increments.

Very few alternators, even brand new top quality units correctly installed, can output anywhere near their rated output for more than a very short time.

Special voltage regulators or B2B DCDC chargers are usually needed to throttle current output

in order to maintain the correct charging voltage setpoint, and keep overtemp conditions from halting proper charge output or burning up the electronics.

Thanks for the feedback.
Much of the concepts you describe here were in the back of my mind. One problem is full-time headlights. If I knew how to disable them, I would have long ago. Another problem is that a test based on just charging the drained batts without any other load is not a real-time situational test. Mostly, it will be the other way around: battery #1 will just be bumped to start the motor - which starts fast in warm weather at least, so the drain on #1 will be minimal; and battery #2 will be fully charged - yet the headlights will be on, the AC will be on, etc.


One of those tests demonstrated what may be a bad or failing rectifier diode and that may be the issue also. Somewhere in the docs I found was an AC voltage (not DC) test for the alternator, but now I'm not finding it (I'll keep looking). It was something like:
With meter probes connected to the battery poles, AC voltage should be less that 0.1VAC - or was it less than 3VAC? Can't remember the maximum range.

[ol trunt]

Battery to battery chargers aren't cheap but they are way better than the diode system you are trying to get to work. They can be sized to your load and the output of your alternator.

For your reading enjoyment check this one out. It is good goods.
Jack

https://www.ebay.com/itm/Sterling-Po...ty!93030!US!-1

[john61ct]

Originally Posted by Mountain Gnome

a test based on just charging the drained batts without any other load is not a real-time situational test.

Yes but first principle of troubleshooting is to simplify, test a single component at a time, eliminate the extraneous variables until you get that component working properly.

Then add back the complexity incrementally, verifying all is as it should be, one new component at a time.

[john61ct]

Yes Sterling makes good stuff, and the BB series gives a lot more flexibility than the A2B lines.

[Mountain Gnome]

So I just ran the AC voltage test. But my voltmeter only shows AC volts in 0.1VAC increments. The test was done with the battery isolator bypassed.



At idle, I get 0.0VAC across the battery poles. But when I turn on the AC, it goes to 0.1VAC. Back to 0.0VAC when the AC is turned off.


Could that be an over-stressed rectifier diode in the alternator?
An arcing (i.e. high voltage) short in a blower motor?
Could that be the problem with the AC pulling its power from the alternator directly, without the battery to buffer the voltage direction fluctuations?
Or is it even an issue.


Still can't find the directions for that test. I swear it was part of the Sure Power isolator installation instructions. But maybe I saw it on a utube video I watched to see if I could figure out on my own how to add the "S" wire connection.


tomorrow I see if I can take the alternator apart without removing it from the vehicle, which may require removing the radiator to loosen the fan belt. Oh no, not that again

[TJones]

Originally Posted by Mountain Gnome

So I just ran the AC voltage test. But my voltmeter only shows AC volts in 0.1VAC increments. The test was done with the battery isolator bypassed.



At idle, I get 0.0VAC across the battery poles. But when I turn on the AC, it goes to 0.1VAC. Back to 0.0VAC when the AC is turned off.


Could that be an over-stressed rectifier diode in the alternator?
An arcing (i.e. high voltage) short in a blower motor?
Could that be the problem with the AC pulling its power from the alternator directly, without the battery to buffer the voltage direction fluctuations?
Or is it even an issue.


Still can't find the directions for that test. I swear it was part of the Sure Power isolator installation instructions. But maybe I saw it on a utube video I watched to see if I could figure out on my own how to add the "S" wire connection.


tomorrow I see if I can take the alternator apart without removing it from the vehicle, which may require removing the radiator to loosen the fan belt. Oh no, not that again

I think your looking for a problem where there isn't one. There would be 0 volts AC between the battery posts. The AC current is produced in the alternator windings and rectified to DC by the tri diodes. If the alternator is charging (even if a little low at idle) and your batteries are isolated then there is no problem. Run this alternator until it dies then replace it.

Ted

[Mountain Gnome]

Originally Posted by TJones

I think your looking for a problem where there isn't one. There would be 0 volts AC between the battery posts. The AC current is produced in the alternator windings and rectified to DC by the tri diodes. If the alternator is charging (even if a little low at idle) and your batteries are isolated then there is no problem. Run this alternator until it dies then replace it.

Ted

When the rectifier diodes go bad, they no longer convert the AC to DC; or at least start to leak a little. That was a test I saw or read about.


I'm looking for any problem. Any excuse to replace the alternator altogether with a new one from Prestolite. They make ones for school buses that produce significant amperage (was it >60% of their rated capacity? I don't remember now) at idle. And they make them already set up for use with a battery isolator.

[Doktari]

I would consider replacing it with a marine grade alternator and programmable multistage regulator with temperature sensor an amperage control. Then add a shunt and a good battery meter amphour counter. But I like high performance energy systems. It’s my hobby.
Currently I’m trying out a Kisae DC-DC Charger in the 4 window bus. I bought the remote panel so I can see the display from the drivers seat. It’s 50 amp max but until I clean the pulleys and replace the belt Ive been running at 35-40 amps which is about 500-600 watts.

[Mountain Gnome]

Originally Posted by Doktari

I would consider replacing it with a marine grade alternator and programmable multistage regulator with temperature sensor an amperage control. Then add a shunt and a good battery meter amphour counter. But I like high performance energy systems. It’s my hobby.
Currently I’m trying out a Kisae DC-DC Charger in the 4 window bus. I bought the remote panel so I can see the display from the drivers seat. It’s 50 amp max but until I clean the pulleys and replace the belt Ive been running at 35-40 amps which is about 500-600 watts.

Thanks for the suggestion. But cost is a factor. Yet I need it to all work in the end.
Before I invest in DC-DC chargers, I would put my $$$ into a better alternator that produces high current at idle. Prestolite's Idlemax line or something like that. They sold me on them via utube, when I was looking for info on my specific alternator.
Again, my alternator is 160amps.
My #2 battery will be at first just an extra starter battery that I have. I'll mildly deep cycle it, but I want it back to fully charged after a short run to the grocery store. Or 15 minutes of idling if I'm deep in the woods and need power for some reason. I have a LED light magnet thing that sticks to my ceiling, that runs off 2 AA batteries that last me a year or more. I put old AAs in the light that I used for a portable digital audio recorder. That thing sucks batteries dry, and they only last in the recorder for a few hours (10-12 max). But I put them in the LED light after that, and they last another 6-12 months. I just need some power for a laptop and external monitor. And probably I'll run a line for a fan in the roof hatch and that line will be on batt #2. And soon I will install the stereo system. That will draw some serious current, running a head unit and 2-4 amps.


I like to live simply. In the woods, I won't use the laptop or stereo. Watching the trees swaying in the wind and listening to the sounds of the birds and crickets is better.


I already got the alternator out, easy like. No need to remove the radiator to loosen the serpentine belt. But getting the belt back on will more tricky...


Now, where's those mod instructions?...page 2 I think...

[john61ct]

Marine alternator means little, waste of money.

Prestolite / Leece Neville designed for fire trucks ambulances

NOS or rebuilt units on eBay for $2-300.

But yes to converting to an external VR, especially if an LFP bank is in your future, may not even need the DCDC

Balmar MC-614 is a classic

[Mountain Gnome]

So the verdict came in this afternoon. No working alternator. Now it won't charge even when the isolator is bypassed.


Oddly, something is acting different now. Before I had ~7VDC at the alternator pole on the isolator when the key was turned on, motor off. This is with the "E" (exciter, ignition) wire attached to the isolator. Now I have 12.15VDC with the battery at 12.23VDC (key on, full time headlights on).


Why the sudden difference? (don't worry, I'm just asking myself)


Once the motor starts, the alternator pole drops to 11.73VDC, with the battery at 12.13VDC.


If I remove the exciter wire from the isolator, the voltage stays below 1VDC, as before. So it is not power coming through the alternator somehow.


I guess now I take it back out and undo what I did and see what happens.


Note I got the voltage regulator off to find a can of worms! Springs popping out. Thought I might not get them back in without taking the whole alternator apart. But then I figured it out.


The springs hold the brushes against the commuter rings. If those brushes or their springs got mis-aligned or something, the alternator won't work. Seems improbable. If I blew a diode or the Voltage Regulator, again, the alternator won't work.


I think I'm gonna try to add another external pole, and connect the original wire that attached to the V.R. Then I can jump that to the new "S" pole (well, I thought it was an "S" pole, anyway) I already just added from outside the alternator, or leave it disconnected and add the external one as the battery isolator instructions say to do.


Some pics for your entertainment. Note the very last one is out of order