Generator/power problems!

[NomadNikki]

Hello! My name is Nikki and I live full time in a 97' Dodge Coach House. I'm having issues with my generator, or possibly with something else involving my power. I'm not terribly knowledgeable about this but if I have a direction to go in I can probably figure it out.

Okay so, the generator starts but I need to hold the button down for about 6-8 seconds each time I start it. This wasn't always the case. It seems to run fine and according to my monitor charges about 4-5 amps. However, after some time, it drops down to anywhere between 0.7-1.7 amps. Sometimes it happens in 10 minutes, other times it's hours.
I can run my microwave most times, but when I try to run my A.C. either it shuts down the generator immediately, or will start and run for maybe 10 minutes and then shut everything down. I make sure everything else is off when I start the A.C. 
I should also mention that when the batteries are being charged by the alternator the same thing happens. Charges fine at first and then drops. Any clues on what's happening here?

Generator is an Onan OG 2800
Recently serviced with new fuel filter and pump

 

[Gary RV_Wizard]

The charging amps almost surely come from the converter/charger, not direct from the Onan, so that taper-off of the amps is probably not related. The charge rates always drops off as the battery gains charge.

It sounds like the genset is having problems sustaining a heavy load, so maybe a voltage regulator or governor problem in the Onan?  I can't think of any external to the genset that would cause the symptoms you describe. The fact that you have to hold the start button down suggests that there is a fault being over-ridden. Possibly low oil? Most all Onans will shut down if a low oil condition is detected. Sometimes just a little low (the oil gets frothy as the engine runs and the pressure droops).

Is this a newer genset, more recent than 1997? You refer to an OG 2800, but did you mean QG 2800, which is the current model of that size?  Is there a model number?    I ask because more recent Onan's have self-diagnostic that give codes to indicate why it shuts down.

Here is a link to a recent model 2800 service manual.
https://b190.com/files/Onan-Cummins%20RV%20Gen.%20service%20manual.pdf

And a late model 2800 Op Manual, if you dont alredy have it:
https://www.lancecamper.com/docs/manuals/Generator%20-%20Onan%202.8K%20Owner%27s%20Manual.pdf

 

[NomadNikki]

Thanks for your quick reply!
Model number is 2.8kvfa26100k

It IS a QG 2800. I typed it wrong.
The thing with the charging amps is that it drops off far before the batteries are even close to charged. Sometimes when I run the generator my batteries are even less charged than when I started it, and I'm having a hard time getting it charged over 12.1-2V.
I'll go through the manual again but I'm just hoping to narrow it down before I try anything because working on it is a huge pain in the ass since it's mounted beneath the van.

 

[Bobtop46]

What is the age (date) of the batteries?  If they are on their last legs your problem might not be with the generator.

 

[Alfa38User]

Note that the Generator does not charge anything. It simply supplies 120V to the RV and then the CONverter charges the batteries, the same as if you are plugged in.

 

[Gary RV_Wizard]

Right - the battery amps and lack of charge is not a genset issue. Very likley the problem is just poor batteries, but it could be an converter/charger problem as well. But not the genset.


I came across another Onan2800 with a similar "dies after a few minutes" type of problem. You might learn something from it:

https://www.justanswer.com/small-engine/7xuc5-onan-microlite-2-8-kvmodel-2-8kvfa26100k-spec-kserial.html

 

[John From Detroit]

First your Generator is 2800 watts. (Same as the model number) so with an A/C. and a Microwave both on.. Well the microwave is about 1000 watts plus overhead (Like 1300 total) and the A/C is up to 1600-1700 So that's a bit more than 2800 (200 more) and I might add that is RUNNING on teh A/C.

That explains the shut downs.  Also the harder the A/C has to work (hotter it gets out. or the more "Debris clogged" the condensers) the greater the power needs.

THe assumption is you have a 13500 or 15000 BTU A/C. smaller ones may draw a bit less.  Still pushing it with only 2800 and I did not factor in Converter (anywhere from a little to a lot) or any other devices (Fridge, Water heater (1400 watts) TV, Computers, Radio whatever)

As for taking longer to start..  Mine too. but one thing that helped is when I had an oil change the technician fixed a stuck choke.  You may need to have routine maintenance done. Plug, Points, Choke, or whaterver.

 

[NomadNikki]

Thanks again for all the replies!

Okay so my batteries were replaced at the end of February, but they do get a lot of use. Could they be bad so quickly? I believe I can get them replaced for free within a year so once I find a place that can do it, I'll try that.

I was always trying to run my A.C. with nothing else turned on, but this time I shut off the converter from charging my batteries and my A.C. worked pretty well for about... an hour and a half before shutting down the generator, and I couldn't get it to stay running for more than 10 minutes after that. Is it just too hot out and it's working too hard? Is there really nothing wrong except bad batteries and a generator that isn't strong enough to consistently power my a.c.?

 

[grashley]

Welcome to the Forum!

Have you gotten on the roof and pulled the A/C cover off?  Clean the coils and you will have much better air flow across them, which means improved efficiency and less load on the A/C.

Check voltage at the battery with a volt meter when the genny is running.  It should be around 13.5 volts.
Check voltage 15 minutes after charging - genny off.  Fully charged is about 12.6V.  At 12.0V, the battery is already 50% discharged and in need of recharging.  Drawing the battery below 50% charge will do permanent damage to the battery.

During a battery charging cycle, starting with a 50% discharged battery, the converter / charger will send max amps (2,7 - 3.0??) to the batteries.  As they recharge, the amps they can take goes down.  At 80% charged, they may only accept 1 amp, and at 90% charge, it may drop to 0.3 amps it will accept.  It may take 3 hours to get to 80%, and another 3 hours to get to 90%, and another 3 hours to get to fully charged.
NOTE: The amps and times are guesses, but the principle is correct.

What type of battery do you have?  Car battery?  Marine battery?  Deep cycle battery?

 

[NomadNikki]

Thanks for helping me understand all of this. I kinda threw myself into RV life with very little understanding of how it all works, but I've been learning and fixing things as they come up. I know a lot more now than I did when I started. Anyway, my batteries are two of the ones pictured in the attachment. I just replaced the ones that were in it when I bought the van.

I can check the voltage, but I have one of those tri-metric battery monitors, shouldn't that be pretty accurate?

I have to replace the A.C. cover tonight or tomorrow so I'll clean the coils while I'm up there. I'm sure having a broken/missing cover led to it getting dirty while I've been waiting for a new one.

 

[NomadNikki]

Pretty sure my image didn't attach.
The battery is an interstate battery SRM-24 Marine/RV "deep cell" battery. From what I understand these probably aren't true deep cell batteries.

 

[NomadNikki]

Okay I'm bumping this because I'm still having problems. Nothing else is running except the A.C. on the generator and it still doesn't stay running for more than 15 minutes. Is there anything else I can check? I already cleaned the ac out. This heat is killing me.