Alternator defective?????

lenp · March 10, 2018

We are into our seventh month on the road this tril (Oregon to Maine to the Carolina's to Louisiana to Texas and back to Oregon) and having an issue with (I believe) the alternator. 2002 Cummins ISL 370 on a Sparton chassis. Nothing electrical has been changed since I installed 750 watts of solar six years ago. About a thousand miles ago I started seeing the dash voltmeter jump to 16.8 volts and the red warning light would come on 2-4 times during a days travel. Voltage would stay at the 16.8 for a few seconds and then return to a lower reading - sometimes as low as 12.2 and remain there for several miles and then jump back to around 13.3 - 13.6 volts.

Today we traveled about 200 uneventful miles before it started to fluctuate. Initially it jumped to 16.8 for a few seconds and then dropped to 12.2 for MILES. I was starting to worry about running the battery down as I had both the heater fan running on high and the headlights on. After about 30 miles it started varying between 12.4 and 12.8 and would occasionally go to 13.4.

I stopped in Hawthorne, NV and wired a Digital Voltmeter to the dash cigar lighter and verified the voltage was indeed fluctuating (thought it could have been a dash panel failure).

Now for a little in depth background on the coach:

1. It has 750 watt of solar with a MorningStar TS-MPPT-60 Charge controller
2. It has a Intellitec's Bi-Directional Isolator Relay Delay (BIRD) that allows charging of both coach and chassis batteries from either engine alternator OR invertor/convertor OR (in my case) solar. This device essentially senses when one bank is charging it closes the isolation relay allowing both banks to charge. Read about it here: https://www.intellitec.com/assets/pdf/1453-intellitec-pdf-template-53-01000-000.pdf

As noted above, this setup has worked perfectly for the last six years. Initially I suspected the MorningStar might be failing and was throwing some higher voltages occasionally. I have a SOLAR cutoff switch installed between the roof panels and the controller so I turned the panels OFF. Problem continued so I am confident the MorningStar is not the issue. If I understand the MorningStar correctly, removing the input voltage results in no output from the controller.

I am now down to either the BIRD or the alternator/regulator. Not sure if the regulator is internal to the alternator or external. Will have to call Spartan and see if they know.

Next step is to disconnect the house battery bank and see if problem continues. Unfortunately hard to do on the road due to residential frig and freezer running on those batteries. We will arrive at our home in Central Oregon tomorrow and can safely disconnect the bank and see what happens.

Have any of my fellow RVers ever seen a problem like this before? I apologize ahead of time for any delay in follow up on this post. It is going to be pretty busy for the next week or two after being gone for nearly seven months.

Thanks for your thoughts,

Lenp

Yarome · March 10, 2018

Why not just disconnect your bird and see if the issue perisists with the alternator and chassis battery isolated. Your house bank can still keep your refer running... although... your refer should be good non powered for 3-4hrs (at least) without issue.

From the sounds of it, it could be the regulator, but could just as easily be the bird. Isolate it out or do a test read (at the alternator) for output.

ALLOY · March 10, 2018

Nothing in the BIRD could cause the voltage to jump to 16V

Yarome · March 10, 2018

10 minutes ago, ALLOY said:

Nothing in the BIRD could cause the voltage to jump to 16V

No one said it could. It could, however, affect what he's reading at the dash and what's moving through his chassis electrical and "could" cause the regulator to be erratic. More than likely it's a regulator issue, but it's still a good idea to isolate the system to diagnose it accurately.

packnrat · March 10, 2018

could try hooking up a meter to the output of the alt. before going into the wire loom. this will prove if the alt is good/bad.

pending parts if you know how/ got tools. easy fix.( delco style is just a couple items from a blister pack, little cost). or just replace the alt.

if other, going to cost just to find out what is the problem. ( shop rates).

.

beemergary · March 11, 2018

Too much voltage is worse than not enough. Will nuke or catch somthing on fire. 16.8 isn't that bad but 14.7 has always been the high side. External voltage regulators went to the way side years ago.

ALLOY · March 11, 2018

23 hours ago, Yarome said:

No one said it could. It could, however, affect what he's reading at the dash and what's moving through his chassis electrical and "could" cause the regulator to be erratic. More than likely it's a regulator issue, but it's still a good idea to isolate the system to diagnose it accurately.

Appologies wasn't meaning to apply that anything was said.

lenp · March 11, 2018

Got home fine today but still had the issue of occasional jump to 16.8. Noted also that dash (and DMM) voltage followed the sunshine today. Increased suspicion of the alternator/regulator. Plan to isolate the two systems next week and see if alternator is putting anything into the batteries.

will keep you posted when I get a chance to work on it. Yard is a mess with pine cones and needles everywhere. Probably take me a week to get it cleaned up!

Thanks for the replies. You all confirmed my thoughts and planned actions.

Lenp

rynosback · March 11, 2018

On 3/9/2018 at 10:06 PM, Yarome said:

No one said it could. It could, however, affect what he's reading at the dash and what's moving through his chassis electrical and "could" cause the regulator to be erratic. More than likely it's a regulator issue, but it's still a good idea to isolate the system to diagnose it accurately.

I agree completely. You can go to about any parts store and get a free starting and charging test. The longer you let it go on the more likely it will also damage your batteries.

Yarome · March 11, 2018

21 minutes ago, rynosback said:

The longer you let it go on the more likely it will also damage your batteries.

X2. If the over voltage you're seeing at the dash are accurate... you also run the risk of potential damage to your wiring and possibly other relays, solenoids and/or sensors. Other than for diagnotic purposes I would'nt be running it at all.

lenp · March 31, 2018

Coach is at the local Freightliner shop for the last week. Got the call today that the alternator output voltage is varying significantly. In addition engine batteries are showing signs of failure. Not sure what the "signs" are but they are nearly six years old. It was slow to start the last few weeks so could have been batteries.

Also had several fault codes including "over voltage" on one of the sensors (can't remember which one). That does not surprise me with the voltage jumping to over 16 volts randomly (and perhaps higher).

New alternator and batteries on the way.

Assume this is the end of the story unless you hear more in the future.

Thanks for all your replies!

Lenp