10k gen. start problem

[Jim Skatzka]

We have a 10k onan genset in our '06 patriot.  As of yesterday we started having problems.  When gen start button is pushed, nothing is happening.  When I start the coach motor and let it run for maybe 30 seconds, then hit the gen. start it starts every time and will continue running when coach motor is shut down.  Also this morn. while running gen. and making breakfast, the second I turned our toster oven on, it flipped a breaker in the main box.  It never did that before!  I'm having a hard time thinking there could be a connection with the problems?? or where the problem lies.   Any thoughts would be appreciated.    

[Gerald Farris]

Jim,
There is almost no chance that the two problems that you ask about are related. The first problem with not starting is (with high probability) related to the way that Monaco wired the generator starting circuit on your coach. On the '06 Patriot, Monaco used the house batteries to start the generator.  So if the house batteries are discharged to about 11.5V or less with normal usage, the generator will not start unless you start the engine to charge them back up or hold the boost switch down while starting it.  The solution is to rewire the generator starter to the chassis batteries, or never run the house batteries below 11.9 to 12 volts.

The tripped circuit breaker is an unknown problem that will require more information to diagnose. I will need to know what the amperage draw on the circuit was when it tripped, before I can offer any suggestions.

Gerald

[Jim Skatzka]

Gerald thanks for the quick response.  The morning that this happend I had been running the gen. most of the night and my batt. level was showing about 12.6 volts with 6 month old lifelines.  Your idea of switching to the chassis batts. sound like the right thing to do.  Guess I'll just start crawling around and figure out how to switch them.  On the other problem, when I'm plugged into shore power, I don't have breaker problem.  Back to the drawing board!  
Jim

[Jim Skatzka]

OK, I've been plugged into shore power for a day.  Batts. fully charged.  Gen. still will not roll over unless coach motor is running?   Any ideas!   Thanks again.  

Jim

[Steven Link]

Jim,
I don't know if this will help you but when my coach starts doing weird things like this the first thing I do is a reboot. Turn off both hard switches to the chassis and house batteries wait about 5 minutes then turn both switches back on. This essentially reboots the multiplex control units. It sounds like the multiplex is not sending power to the generator start circuit. It's worth a shot.
Steven

[Gerald Farris]

Jim,
It sounds like you have a bad connection in the battery cable between the house battery bank and the generator. The best way to locate the problem is to take a volt meter and trace the battery cable, starting at the generator and going back to the battery bank.

If the battery cable has 12.7 volts at the generator starter, try to engage the starter, if the voltage does not drop, check for a problem in the starter. If the voltage drops substantially, check for high resistance in the cable.

Gerald  

[Edward Buker]

Jim,

In addition to Gerald's insight that there is a main cable that goes to the starter where the cable or a cable lug could have a high resistance, there is also the control circuit of the starter including the switches, wiring harness, and the starter solenoid that has to have enough voltage and current at the solenoid to cause the solenoid contacts to close when the start switch is depressed. Basically you are looking for voltage drop in either the high current large cable path as well as the smaller wire control circuit when the starter switch is depressed.

 I think what may be happening is 12.6V is not enough voltage with the long harnesses to quite cause the starter solenoid to fire but the 13.6v with the engine running it is. You should take a voltage measurement at the smaller solenoid wire that fires the starter solenoid with the starter switch engaged and see what the voltage is with both the engine running and without the engine running. If it is a marginal voltage (say 10.5V or below) with the starter switch engaged and the engine not running but 11.5V+ or so with the engine running then you may have to find a way to provide a higher voltage to the starter solenoid. This could be an extra relay circuit or an improvement in a contact point or a run of heavier wire.

Later Ed

[Jim Skatzka]

Thanks for the ideas.  I went out this AM and it fired right up.  I was too busy today to look furthe,r but will be on it tomorrow.  I think the connection problem is the right track!  Thanks for the responses, I'll let you know.  
Jim

[Bill Sprague]

Intermittent and unpredictable behavior in 12 volts systems is often related to a bad ground wire connection somewhere.  

Bill

[Jim Skatzka]

Thanks to everyone.  I still have not found the culprit, but will wait till it happens again.  If I find the problem, I will post my findings.  Thanks!    
Jim

[Jeff Watt]

I had a couple of issues with my genset so I searched and found this post. I too have problems very similar to Jim's.

On the way to Texas we stopped overnight at a walmart, used the batteries that night to run the aqua hot fans, the residential fridge and some lights and tv. Next morning went to start genset and a no go until I started the coach. I can't remember what the battery levels where but I assume probably just around the 12 mark - low but I didn't think too extensive given I was planning on using the genset to recharge.

In Texas for three months and so before I leave I checked the genset - no problem starting using the external switch. Of course the batteries should have been fully charged as plugged in for 3 months.

On the trip home we stopped for lunch and tried to start the genset - no go until I started the coach. The inverter had been on as we were driving. Also it was probably after 3 hours of continuos engine running. I seem to remember the house batteries where around 12.8 (is this to low) dropped when slide went out but recovered somewhat.

I have not tried to start it since arriving at home and unfortunately the way I had to quickly park it in the shed I can't open the genset door.

My questions are:

My house batteries poor - they are original agm type. so they should be load tested?
Poor connection from battery bank to genset (or Ed's thought about the starter controller)?
Bad switch in cab (I need to do a check to see if it starts now from cab) will have to wait until snow stops and i can move the coach out of shed before I can check external switch).
How (and is it a good idea) to switch from house to chassis to start genset. My 05 patriot used the chassis batteries to start the genset and I had no problems.

I am thinking that my batteries may be part or all of the problem since for the size of the battery bank they run down pretty quick from just the fridge and a few other things (I know the inverter takes quite a bit of power)

Any thoughts or advice is appreciated as I'd like to be able to fix the issue so I can at least dry camp once in awhile without being paranoid about whether the genset or worse the engine won't start. (somewhat unnerving when it happened the first time not knowing if the engine would start).

As a minor side note, the engine starts well first thing in the morning being plugged in overnight. Do the Air up, shut down engine, put slides in, restart and i get "low battery" on the digital readout but it still starts well, maybe not as fast as first time but still adequate. Is this normal or is it an indication of potentially poor chassis batteries as well?

Thanks,

Jeff

[Edward Buker]

Jeff,

It sounds to me like you may have batteries involved that are showing their age. Usually the generator starting uses the chassis batteries. If you put a voltmeter on the chassis battery terminals and press the start button on the generator. See if you see a voltage drop at the battery. If not do the same with the house batteries and see if you see a drop while trying to start the generator. If you find that the chassis batteries are being used, they are a few years old, and you get the low battery indicator for them I would change them out.

The house batteries may also be an issue. If they do not hold a charge well you can have a bad cell in one that will put extra strain on the alternator. You could disconnect them all after they have been charged by the inverter and have each of them load tested. Most of the time these issues are battrey or charging system related, especially when you can get the genset to start when you start the engine first. That means the alternator is augmenting the batteries to get your genset started. It could be a marginal connection but you would need to know that the batteries are delivering what they need to before heading down that path.

Later Ed

[Jeff Watt]

Ed,

I assumed from the info provided to Jim that my house batteries start the genset as my 07 is probably wired the same as his 06.

I had a feeling that the batteries may be the issue. Of course I had replaced the batteries on the previous coach then sold it, so i get to go spend more $ on batteries - i guess in the grand scheme of things that is a fairly small expense especially when the consequences of a poor bad battery are considered. Nevertheless it annoys me that I didn't have the batteries tested before i bought this coach - assumed they were ok. Can't wait to find out how much two chassis batteries and 6 (but two are double size)  house batteries will cost  especially if I replace them all with AGMs as that is what is in it now

Jeff

[Edward Buker]

Jeff,

I am not sure which batteries start the Genset. If you have a chassis and house cut off switch you could see if with the house switch off if the generator clicks or starts and if it does then I would assume that the generator uses the chassis batteries. If they are original I would change those out given the age.

I feel your pain if you do the house batteries, I just bought 6 Trojan lead acid for mine....
Later Ed

[Dwight Wilson]

Hey Jeff:
Just wondering if you tried the battery boost switch (ties both banks together) to try starting the genset before you started the coach. If the result was the same dead battery I would suspect there is a problem with the converter charger circuit. You are also probably aware that the AC inverters are not very efficient re the residential fridge, stereo, TV , microwave, etc. , and those fans and electric element on the Aquahot can be a bit greedy and can put some burden on the coach batteries. If the cells are low on fluid (distilled water), which can happen when plugged in charging for a period of time with no load, the batteries will not be able to sustain a charge. Also could be a problem with the charging system from the alternator. The batteries may be fine or recoverable.
I do like the new batteries though!