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  • bigdog
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More Alternator woes
As my coach seems to like stressing me out. It of course decided to continue with almost no voltage from my new (not Reman) Delco-Remy 28si 180amp alternator. As this alternator doesn't need an excite wire. I terminated that one and insulated it....

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  • Tim
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Re: More Alternator woes
Reply #1
Bad alternator.

  • bigdog
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Re: More Alternator woes
Reply #2
Bad alternator.
I hope so as that's an easy swap.
Need to find a shop that can test one. NAPA here is useless as it's not one of theirs so the computer has no data for it. Geez. You think they could...

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  • John44
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Re: More Alternator woes
Reply #3
Had the same hassle at Auto Zone,Installed a 160 amp 28si 2 years ago along with a new isolator and everything new on the
mounting plate,haven't had a problem,charges much better at low rpm.

  • bigdog
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Re: More Alternator woes
Reply #4
Well against my better judgement. I decided to save a few bucks and went big box truck parts place. Should have spent the coin and stayed local. A local truck shop that does my oily work has the 28si 160amp. I think I will go with that.

Re: More Alternator woes
Reply #5
Nothing wrong with the alternator. Delco alternators won't work with a standard diode isolator, they need +12 volts on the B+ post to initialize the regulator chip. Either install a diode isolator with an ignition excite post, or wait until you...

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Re: More Alternator woes
Reply #6
It will work fine with your Sterling as Peter says.

  • bigdog
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Re: More Alternator woes
Reply #7
Nothing wrong with the alternator. Delco alternators won't work with a standard diode isolator, they need +12 volts on the B+ post to initialize the regulator chip. Either install a diode...


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Re: More Alternator woes
Reply #8
Jerry, you're not the first one...contrary to what you may have heard, Delcos are not a drop-in replacement alternator in a 2 battery isolator system. A diode isolator with excite post or the Sterling isolator with excite post will work with a...

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Re: More Alternator woes
Reply #9
Hook up only the sense wire to the S post, nothing to the I or R posts, in addition to the big ground and the B+ output cable.

  • bigdog
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Re: More Alternator woes
Reply #10
Hook up only the sense wire to the S post, nothing to the I or R posts, in addition to the big ground and the B+ output cable.
That's the way I have it hooked up now.

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  • bigdog
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Re: More Alternator woes
Reply #11
OK, So as i'm looking at the old diode isolator. The main thing that confuses me is that at both outputs. There are smaller wires on those terminal along with the big battery cables. What are those?

Re: More Alternator woes
Reply #12
This will get you going until you get the Sterling.

Delco compatible isolator

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  • bigdog
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Re: More Alternator woes
Reply #13
This will get you going until you get the Sterling.

Delco compatible isolator
I already have the sterling. I was just going to use the old iso until it isn't 100 degrees out. As in this fall...

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  • bigdog
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Re: More Alternator woes
Reply #14
OK. After reading and re-reading Rogers old post on his switch to the Delco/Sterling combo.
 
I terminate the old sense wire, Then run a new sense wire from the Delco S post to the Sterling Sense post.

Then I need to run a wire from the old FT...

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Re: More Alternator woes
Reply #15
Hi Jerry,
It is pretty straight forward.  The Sterling sense to the Delco S post is right.  The Sterling ign  post needs an ignition powered wire to turn on so the excite wire will work.  Often times these old wires have corroded connectors.  I...

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  • bigdog
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Re: More Alternator woes
Reply #16
Thanks Roger. I will look at the wiring chart before I get started. Not supposed to be as hot today & Sunday. So that will help. 100 degrees like it has been and parked on a sticker infested patch of dead grass with no shade is not a good...

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  • John44
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Re: More Alternator woes
Reply #17
Peter was also a big help when I installed mine,good to see your still out there.

Re: More Alternator woes
Reply #18
The "I" post is for indicator lamp. Connecting excite to this will permanently damage the alternator.

I only work on old stuff and only for my pleasure, but Delco used to use the "generator"...

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Re: More Alternator woes
Reply #19
I only work on old stuff and only for my pleasure, but Delco used to use the "generator" light to provide the exciter voltage to the alternator. Bad light bulb means no alternator output.
...


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Re: More Alternator woes
Reply #20
You're right I think the old Delcos (before Sense technology) worked this way, the new Delcos have output with nothing connected to the "I" post.
On the flat bottoms we put a resister between...

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Re: More Alternator woes
Reply #21
Maybe the 2 small wires at the isolator go to a battery maintainer for the chassis battery, like a battery tender or heart echo charger.

  • bigdog
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Re: More Alternator woes
Reply #22
Maybe the 2 small wires at the isolator go to a battery maintainer for the chassis battery, like a battery tender or heart echo charger.
I did see one wire on the wiring diagram that goes to...

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Re: More Alternator woes
Reply #23
Guess I missed that memo.
Here is the Delco bulletin on using the 24SI with isolator, this also applies to the 28SI, 40SI.
 


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  • Last Edit: August 11, 2019, 11:19:31 pm by prfleming

Re: More Alternator woes
Reply #24
Upon starting the coach, I went to high idle (1000 RPM) and saw low volts at the gauge.  Then I measured voltage at the center terminal of the isolator. 1.7V.  Measured the voltage at the pos...


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