Alternator, regulator, solenoid, or ???

Topic: Alternator, regulator, solenoid, or ??? (Read 1275 times) previous topic - next topic

Alternator, regulator, solenoid, or ???

October 10, 2016, 09:16:43 pm

See my other threads for the background for this.

During the previous driving day's travels I paid attention to the voltage at various times and places. Here is what I found:

Prior to starting the engine, shore power removed, I had 12.68 volts on the start batteries and 12.28 at the solenoid under the dash. Engine running at 1000 rpm it was up to 14.30 at the batteries and 14.02 at the solenoid. After about 30 minutes of driving the dash voltmeter was down to just under 12 volts, from just under 14 volts at startup. At lunch, engine running at 1000 rpm I got 12.23 on the batteries and 12.02 at the solenoid. After lunch, prior to starting the engine it was 12.38 and 12.34 volts, engine and solenoid. With the engine running it was 13.34 at the batteries and 13.04 at the solenoid.

I didn't check things on today's drive since we had a longer drive, but the dash voltmeter was behaving about the same - started out near 14 volts, dropped to about 12 after 30 minutes or so, then gradually slid down to about 11.

I'm thinking that I'll order a new solenoid from Amazon tomorrow evening and see what happens then. Our next travel day (hopefully) will take us to Cabin Diesel in Big Cabin, OK, about 150 miles away. I'll alert them to what's going on and if things aren't behaving themselves with the new solenoid maybe they can lay hands on the alternator/regulator. I'm told that such problems often can be resolved simply by the presence of a mechanic with tools in hand.

Re: Alternator, regulator, solenoid, or ???

Reply #1 – October 10, 2016, 10:03:30 pm

David,

This statement "After about 30 minutes of driving the dash voltmeter was down to just under 12 volts, from just under 14 volts at startup. AND At lunch, engine running at 1000 rpm I got 12.23 on the batteries and 12.02 at the solenoid" says you have an alternator/sense wire issue.

Did you measure voltage at the chassis battery side of the ignition solenoid or the "out" side. The battery side will tell you voltage drop over the wire run. Check from one side to the other of the ignition solenoid will tell you the loss in the solenoid.

If you indeed have a real loss in the solenoid, there are some excellent zero drop alternatives-- let us know.

Address this first.

Re: Alternator, regulator, solenoid, or ???

Reply #2 – October 10, 2016, 11:57:30 pm

I moved the big cable to the other side of the solenoid to eliminate it from the circuit and see if it fixed my voltage fluctuation problem and it did, so I bought a new solenoid. Be very careful not to touch anything with the big cable because it's a live wire straight from the cranking batteries.

Re: Alternator, regulator, solenoid, or ???

Reply #3 – October 11, 2016, 08:41:16 pm

Brett, do you have a suggestion? I've got some other things I need from Amazon, so adding a solenoid is no big deal with Prime.

Scott, the first thing I do before working on electrical stuff is disconnect the power. In this case, the engine batteries will be disconnected, so nothing should be hot under the dash. Once the new solenoid is in place I'll clean the battery connections before reconnecting them. I generally clean them annually, or whenever I disturb them.

Re: Alternator, regulator, solenoid, or ???

Reply #4 – October 11, 2016, 08:50:04 pm

David,

I am not advocating the replacement of a perfectly good ignition solenoid, but if you determine it is giving symptoms, here is an excellent (1 million cycle) e-switch: L Solenoid - 12/24V DC 250A - Blue Sea Systems

Re: Alternator, regulator, solenoid, or ???

Reply #5 – October 11, 2016, 09:34:21 pm

The batteries are filled with sulfuric acid and can emit flammable hydrogen gas. A spark there could be far worse than a spark under the dashboard. I'd wrap electrical tape around the tool(s) and the cable as soon as you remove it, or just have a helper hold the cable securely for you. I certainly don't disconnect the batteries without good reason. They're the most dangerous part of the system. At least put on safety goggles with side guards before you work on the batteries. You don't want that acid splattering in your eyes.

Re: Alternator, regulator, solenoid, or ???

Reply #6 – October 25, 2016, 02:13:17 pm

I ordered the solenoid Brett mentioned and installed it this morning. I checked the voltage prior to the change and then afterward, mainly to make sure that all power was off before I started sticking my fat fingers in all those wires. I should have written down the voltages, but there was about a half volt increase from the old solenoid to the new one. Monday is a travel day, so I'll keep an eye on the dash gauge. We'll be stopping at Cabin Diesel in Big Cabin, OK for some service, and if the gauge is still showing anything funny we'll call ahead to see if they can check it out.

Re: Alternator, regulator, solenoid, or ???

Reply #7 – November 01, 2016, 11:20:50 am

Well, after replacing everything else, I'm getting a new alternator. The new one is an AC Delco, to replace the Leece-Neville. Is this right? According to the guys here at Cabin Diesel this is a direct replacement. They know that there is an exciter wire and a sense wire. I thought that tne L-N alternator was ~$600. This one is $350.

Am I asking for trouble later on, or is this an acceptable replacement?

Re: Alternator, regulator, solenoid, or ???

Reply #8 – November 01, 2016, 11:33:25 am

Think that is a matter of preference and opinion and your wallet,I had my LN rebuilt for $250 and that included a new shaft,runs
good on my stock coach.Part of the thinking was it was good enough for the first 200k miles.

Re: Alternator, regulator, solenoid, or ???

Reply #9 – November 01, 2016, 12:01:21 pm

David,

Just make sure it has been modified for DUVAC.

I am beginning to think that is the source of my alternator problems. It was replaced last year by a "new" alternator, for which they only charged me about $350 (plus labor). It was done by "one of the top five diesel engine mechanics in the country." I suspect it was for a truck and might not have been DUVAC capable; will check later to see.

Good luck!

BTW, you are only about an hours drive away from me.

Trent

UPDATE: I checked and I *DO* have a DUVAC modified alternator with a lead to each of the two extra terminals. I had hoped that my problems was that he gave me a truck alternator instead of an RV alternator. I guess the next step is to measure the voltage at those two terminals with and without the ignition on. Hopefully the sense wire is broken somewhere along its path. It is not coming from the isolator, so I have to start at the other end and see where it goes/comes from. If I can't find it then, I will just run a new sense wire and see if that works.

[He had originally tied the alt output and the engine battery positive together. When I moved it back to the engine stud on the isolator (so my echo charger could work), I was seeing 15+ volts on the coach batteries. I moved the engine battery plus back to the center isolator stud and it works okay, except need the boost to charge the engine batteries when the engine is not running.]

Re: Alternator, regulator, solenoid, or ???

Reply #10 – November 01, 2016, 12:25:45 pm

Read this about DUVAC

Leece Neville DUVAC Alternator

Re: Alternator, regulator, solenoid, or ???

Reply #11 – November 01, 2016, 12:46:07 pm

David, you don't say which Delco alt you got but the 24si and 40si groups all wire up the same way.

Ground to ground, B+ to the alternator and S to the sense wire. No excite needed. Other than that pretty much the same as a LN. You can (should) use the existing pulley. Feel the belt tension and set it the same if you don't have a belt tension device.

Peter Flemming was very helpful with this. The Sterling isolator threw us a couple of curve balls.

Re: Alternator, regulator, solenoid, or ???

Reply #12 – November 01, 2016, 05:03:16 pm

Roger,

Quote from: Roger & Susan in Home2 – November 01, 2016, 12:46:07 pm

David, you don't say which Delco alt you got but the 24si and 40si groups all wire up the same way.

Would that also be true of the 33si?

Quote from: Roger & Susan in Home2 – November 01, 2016, 12:46:07 pm

Ground to ground, B+ to the alternator and S to the sense wire. No excite needed. Other than that pretty much the same as a LN.

Is that true for all Delco-Remey 24si, 33si, and 40si? They do not have to be DUVAC modified (or are they all already manufactured to be DUVAC compatible)?

BTW, 33si and 40si are brushless and 24si is not; is that correct?

Thanks,

Trent

Re: Alternator, regulator, solenoid, or ???

Reply #13 – November 01, 2016, 05:26:34 pm

I put in a brushless 240 amp 40si alternator. Wiring for other alternators may be different.

The 33si is a brushless alternator. You need one with the J180 long hinge mount, at least that is what I needed.

Remote Sense is a feature available on Delco Remy alternator models: 35SI™, 36SI™, and standard on the high output alternator models 28SI™, 38SI™, 40SI™, and 55SI

Medium & Heavy Duty Alternators | Delco Remy

The 24si alternators apparently need an excite wite to the B+ terminal. See PDF.

Alternators by Model Family | Delco Remy

To be sure ask a qualified alternator person. I know what worked on mine.

Re: Alternator, regulator, solenoid, or ???

Reply #14 – November 01, 2016, 05:47:37 pm

Quote from: Roger & Susan in Home2 – November 01, 2016, 05:26:34 pm

To be sure ask a qualified alternator person. I know what worked on mine.

Roger,

You're good enough for me.

Thanks,

Trent

Re: Alternator, regulator, solenoid, or ???

Reply #15 – November 01, 2016, 07:18:57 pm

Well, we're back in the campground, and the techs want me to bring it back in first thing in the morning. Replacing the fuel lines wasn't much of a problem, but the alternator still has them puzzled. Apparently it is putting out only about 12 volts no matter what. They finally decided to call it a night at about 6 (shop closes at 5), sleep on it, and see what the morning brings. Our plan for tomorrow is only about 200 miles, so this small delay shouldn't be a problem.

More tomorrow.

Re: Alternator, regulator, solenoid, or ???

Reply #16 – November 01, 2016, 08:19:59 pm

what is DUVAC

Re: Alternator, regulator, solenoid, or ???

Reply #17 – November 01, 2016, 08:49:33 pm

Quote from: Bill Chaplin – November 01, 2016, 08:19:59 pm

what is DUVAC ?

Reply 10

Re: Alternator, regulator, solenoid, or ???

Reply #18 – November 02, 2016, 11:24:01 am

Hmmm, I'm seeing a pattern. The brand new alternator, right out of the box, is defective. A new, new one is on the way from Tulsa, and they expect us to be on our way by lunchtime.

More than 40 years ago I was moving from Lincoln, NE to Potter, WI in a nearly new Ryder truck. I got only about 30 miles down the road when the truck quit. Turned out that I was running on the battery and I had the headlights on. New alternator was installed, and it was dead, too. Second one installed. It worked properly, and then they discovered that the factory never hooked up the volt meter on the dash. At least the dash volt meter is hooked up on my coach.

Re: Alternator, regulator, solenoid, or ???

Reply #19 – November 02, 2016, 09:11:03 pm

We're landed in Chickasha, OK for the night, so a little more information.

When we called it quits last night, the new alternator was putting out just over 12 volts, measured at the alternator, no matter what. The techs wondered if all of the new electrical stuff (isolator, solenoids,,etc.) were before or after the alternator misbehavior. They were concerned that maybe something wasn't wired correctly. After some sleep, I came to the same conclusion they did - check the alternator with NO load. No change in voltage, even with a jumper wire for sense and excite. Conclusion: new alternator is defective, and a new one was gotten from Tulsa. New one worked perfectly.

Yesterday, after changing the fuel lines for the generator, the generator would shut down immediately after starting, even before any load was added. The problem was traced to an oil pressure sensor, and a new one was installed. The new one is adjustable. The generator started and ran fine when they tested it, but they didn't leave it on very long. Since it was warm, as soon as they had released the coach, I fired up the generator and turned on the a/c while we hooked up the Jeep. We were just pulling out of their lot when the generator quit. I turned around in the truck stop across the highway and returned. Questioning looks from the employees as I said the generator quit. One of the techs knew what the problem was immediately and grabbed some tools. Two minutes later the oil pressure sensor had been turned down a bit more and the generator ran perfectly from there to here.

The new alternator needs some rpms before it will kick on, so firing up the engine and letting it idle won't do much. Once it gets 1500 rpm or so it will happily begin charging. I saw an unwavering 13.5 volts on the dash all afternoon - even with the headlights on.

Looks like problems are fixed.

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