Looks like a bit of green corrosion on the cables connected to the isolator. Good idea to pull them, clean them up, and coat with something. While you have them off bend them and make sure they don't feel crunchy. If they do there is corrosion inside the wires. That could cause resistance and could add to your problem of low voltage.
I ended up pulling all the wires off the batteries (and as Richard said) they were wired wrong/wierd. I cleaned up the terminals with wire brush and then coated them with protective spray (that I left in my shop also)... Dumb question but are you basing your voltages off the dash or do you have something like a VMSpc? I know on my coach I no longer trust the dash even after cleaning all the connectors... My alternator is a PennTex and they gave me clear instructions on how to test the system - you might contact your mfg and see what they recommend to test. Above all, DO WHAT RICHARD ASKS (he is awesome at this stuff and saved my bacon yesterday!)...
Dumb question but are you basing your voltages off the dash or do you have something like a VMSpc?
First, I find there are no dumb questions here...LOL
My VMSpc and dash gauge are very close, but I rely on the VMSpc as it seems to be more accurate, and its telling me that I'm down at 11.7 +/- at times while driving.
I will be traveling this Wednesday or Thursday after having cleaned all terminals, and report back, hopefully better numbers.
Update;
At start up the batteries are low at 12.3, raising the RPM's to 800 to 900 gets the volts to 13.4. After driving for 2 hours it stayed near 13.8 to 14.2. After the 3rd hour it started going down. It got down to 11.7V. I let it stay there for about 15 minutes to see if it would pick back up. It didn't. I merged the batteries and started the generator. It brought it back up to the high 13's after about 10 to 15 minutes. I was afraid at keeping it non merged and getting down to 11's would possibly shut the motor off with a low voltage to the fuel solenoid. I'm not sure what the voltage would be to shut it off, but I didn't want to find out at speed.
Thoughts appreciated.
I would check for belt slippage. Do you see any difference when running the dash AC?
If that is not the case, then I would throw a regulator at it since the alternator appears to be capable of producing the necessary voltage and amperage.
And I think you were smart to merge and run the gennie. I don’t know exactly the voltage tolerance on the computer that runs the engine and the transmission, but I wouldn’t want to find out on the freeway.
i had an issue once where my voltage wandered up and down in the same ranges you are talking. ended up being a loose wire on the voltage regulator.
i have a 50dn alternator and a separately located regulator
tom
Ok advice from an authorized distributor, "The voltage regulator is solid state, it works or it doesn't. He suggest bringing my alternator down and having him bench test it. He thinks it may be a Diode or something that is effected by heat. I'm driving again tomorrow. I'll take it off at my new location and have a shop bench test it there. He has a used regulator that I could throw at it but I'll do the testing first.
To be continued..
Ok, Final chapter. You guys can be honest with me, I think I was taken.
Bench test reveals the alternator is bad. I'm always skeptical. I asked specifically what was bad, after testing he said the heat sink was bad and heating up the Alternator and causing the unit to only allow minimal amperage out (down to about 75-100) which in turn it gets hotter and shuts down. That doesn't make sense to me, but he rebuilt the alternator, added new bearings and new external regulator. The alternator seamed to work fine in the driveway, so a trip is needed to verify over time and heat.
I spent 2/3rds$ the price of a new alternator. If I got screwed, he's on my list...
BTW, all connections at the Alternator were tight, and all connections (battery, transfer switch) were removed and cleaned before the last trip. The last trip only allowed recharging for about 1/2 hr, then I had the generator running. But the generator stopped after 2 hrs, I could restart it but it would then last for about 1 hr. This got me to my next location.
Question, can a heat sink go bad ? I thought a heat sink, when I need one for welding, is nothing more than a mass to pull heat away from the heat source. Nothing mechanical about it. According to the repair shop, they can go bad.
You may have gotten a technically inaccurate explanation of the issue. Time will be the judge of the effectiveness of the fix.
Did you notice any overheating issues when the gen shuts down? And based on my recent similar experience of unexplained gen shutdown, it wouldn’t hurt to change the fuel filters.
Agreed. It may be what I "heard" and "my' understanding of the technical explanation.
Generator shut down issue. The last time I had this issue, it turned out that the sensor that signaled a catastrophic failure of overheating or low oil pressure, was killing the Kobota. All gauges and further testing showed that the water temp and Oil pressure was well within operating parameters when the sensors were shutting the engine down. I think I will check that first.
I'm just not sure where these signals go after leaving the engine, so advice is needed here.
The fuel filters are fresh (less than 40 hrs).