Community Forums

barmcd · 06-22-2021, 06:07 PM

Okay, went out and turned the generator on, then started the coach while holding the boost switch. The generator never died in ten tries. I’m going to have Katherine help me tomorrow and see what the battery voltage is while cranking.

Timaz · 06-22-2021, 06:17 PM

Quote:

Originally Posted by barmcd

Okay, went out and turned the generator on, then started the coach while holding the boost switch. The generator never died in ten tries. I’m going to have Katherine help me tomorrow and see what the battery voltage is while cranking.

It's a long cable run so I would check the voltage at the generator.

Tim

barmcd · 06-23-2021, 11:53 AM

If the battery is weak, wouldn’t the voltage drop at the battery be excessive when the starter is engaged?

Timaz · 06-23-2021, 03:42 PM

Quote:

Originally Posted by barmcd

If the battery is weak, wouldn’t the voltage drop at the battery be excessive when the starter is engaged?

Yes but you will see the true voltage at the generator.

YC1 · 06-25-2021, 06:26 AM

Both posters symptoms are low voltage, especially BilJol's comments about the transmission etc. Those run on 12 volts.

The symptoms are masked/ or compounded by the battery combining systems not necessarily being up to par. Worn and intermittent combining solenoids is a very very common problem. Worn contacts cannot carry the current.

Having a five year old starting battery is an absolute recipe for symptoms like these. They may get things started but at the price of pulling the voltage so low it creates issues.

Notice how you can get the blue screen of death on a PC if you get a brown out versus a power out?

Computers do not like the inbetween voltage stuff. The generator has a computer and so does your transmission and engine of course.

If for no other reason than age I would retire that five year old battery.

I rarely ever suggest throwing parts at a problem with almost 50 years of electronics experience but in some cases it is the best place to start with for batteries.

No one owns a battery. We only rent them for a time and they have to be replaced.

If you have a battery combining solenoid that is many years old then replace that too for good measure.

If I suggested you change a filter, folks would have no issue doing that. But getting someone to change a solenoid/relay is like pulling teeth.

Always take pictures before doing any electrical maintenance and take some voltage measurements to write on those printed pictures. You will be happy you did at some point in time.

Cheers

rvhotrod · 06-25-2021, 06:50 AM

I had the same issue, on a random basis until I changed out my chassis battery last year. Has not occurred since, it's been over a year.

Biljol · 06-25-2021, 07:06 AM

My issue is not battery’s they are new and charge fine. I may have issues with the connections to the battery’s that I am fixing this weekend.

But will be a few weeks till I can test.

This last weekend I was able to start my drive engine without the genny quitting never tried the other way around. But it was cold most of the time it’s hot when this happens.

Jeff753 · 06-25-2021, 12:36 PM

Mine was the battery. Cleaning connections didn’t help. Use the battery boost and see if it still does it.

Outbound · 06-25-2021, 02:14 PM

I have had the same problem in the past, but only once or twice, problem went away with new batteries.

Biljol · 06-25-2021, 02:35 PM

Ok I fixed up my leads to the battery’s and I think the issue is better. Loos on the post (long story)

My genset and main engine seem to start better now less luging when cranking.

The true test will be in a couple weeks when we head north for a trip.

ArtJoyce · 06-25-2021, 04:29 PM

Yes, voltage at the battery will drop when starter is engaged. I would expect to see it in the 11v range. Plus or minus 1/2 volt. But once the started stops cranking it should bounce back up to 12.3v plus in 3 to 5 seconds.

itdave · 06-26-2021, 02:15 PM

Kwvwwwawwwe

Tfixer · 06-29-2021, 03:25 PM

What fault codes are you getting when the genny dies?
From the Service Manual:
FAULT CODES
The genset controller provides extensive diagnostics
by causing the status indicator light on the Control
Switch to blink in a coded fashion. Following a
fault shutdown, the indicator light will blink repeatedly:
1, 2 or 3 blinks at a time.
• One blink is code for shut down due to high
temperature
• Two blinks is code for shutdown due to a loss
of engine oil pressure
• Three blinks is code for shutdown due to
some other abnormal condition.
For a 1-blink or 3-blink fault code, one touch to Stop
brings up a second-level fault code. This code consists
of 1, 2, 3 or 4 or blinks, a brief pause, and then
1 to 9 blinks. The first set of blinks represents the
tens digit and the second set of blinks the units digit
of the fault code number in Table 18-1. For example,
Fault Code No. 23 would be:
blink-blink—pause—blink-blink-blink—...

And: ". . . 3 touches to Stop restores [previous] fault
code blinking."

The Operator's Manual has definitions of the fault codes as well.

(The manuals are available here: www dot cummins dot com/rv-generator-manuals)

Tom

Crabbyjerry · 06-30-2021, 08:27 AM

Quote:

Originally Posted by vito.a

I've also had this happen. I think it's the chassis battery getting weak or poor connections. I suspect it stops the generator fuel pump when you are cranking the main engine.

I think you have it. The old Cummins engines needed electric for the fuel solenoid to run. I recall manually turning a screw in on the tractors when the truck had charging or battery issues to keep running and I’ll bet with the engine cranking dropping the voltage, it interrupts the gen solenoid enough to cut the fuel. Good thinking Vito.