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pointrow · 03-12-2016, 03:27 PM

Had this posted in other forum but thought I would try here.
Onan 8kw gen w/Command 30 and Magnum Inverter, 6 6volt batteries which I load tested.
Gen shuts off at `12.5v instead ot 14.1 like it is set at. This causes the gen to short cycle and I can't get the batteries charged enough to last through the night with a minimal load. Evan when I run it on manual for hrs it never gets above 12.5 volts.
It's been like this since new and FW just replaces the batteries. 3rd set in 1 year.
This problem only rears up when we dry camp like we are now at PIR.
Any ideas?
thanks

pointrow

CampDaven · 03-12-2016, 03:34 PM

The Magnum inverter is the control point for this issue. I don't know how to do a reset on it nor how to change the parameters but think a call to Magnum may be a good place to start. If you have the manual maybe you can get some ideas.
Best wishes

Dave and Nola, RV Mutants

Gary RVRoamer · 03-12-2016, 03:41 PM

If the genset actually shuts off early, I don't think the Magnum is the issue, even though its doing the actual charging. The EC30 controller senses the house battery voltage via one of its input wires (the 'purple' one in the manual I have for it). If it is sensing the Magnum's output voltage, it may think the house battery bank is fully charged, but of course that voltage drops as soon as the genset shuts off. My guess is that the sense wire is connected to a place where the voltage reads rather high, causing it to shut down prematurely.

I'm not real familiar with the Onan 30 controller, so this is guesswork based on reading the manual.

CampDaven · 03-12-2016, 04:00 PM

What if you turn off the gen autostart and see if it charges the batteries?

Dave and Nola, RV Mutants

dpinvidic · 03-12-2016, 05:21 PM

Something does not make sense, running it on manual supplies 120 rolls to the inverter. That should be the same as shore power. Do you have a problem on shore power?
From what you are saying, it sounds like the batteries never get charged fully even when plugged into Shore power.

Regards,
Dan

pointrow · 03-12-2016, 05:40 PM

Quote:

Originally Posted by dpinvidic

Something does not make sense, running it on manual supplies 120 rolls to the inverter. That should be the same as shore power. Do you have a problem on shore power?
From what you are saying, it sounds like the batteries never get charged fully even when plugged into Shore power.

Regards,
Dan

I will have to check when on shore problem. Like I said it's never a problem until dry camping so never noticed.
thanks
pointrow

gemert · 03-12-2016, 08:46 PM

Quote:

Originally Posted by pointrow

I will have to check when on shore problem. Like I said it's never a problem until dry camping so never noticed.
thanks
pointrow

I'm going to take a WAG (wild a.. guess) and say that you have the same problem on shore power. If thats the case then the charger in your converter is bad. To check it, with the generator running or plugged into shore power, Check the voltage across the house bank of batteries. See what the voltage is. I'm guessing 12.5. Could also be a bad connection somewhere in the 12 circuit (hopefully.) Good luck.

dpinvidic · 03-12-2016, 10:41 PM

Quote:

Originally Posted by gemert

I'm going to take a WAG (wild a.. guess) and say that you have the same problem on shore power. If thats the case then the charger in your converter is bad. To check it, with the generator running or plugged into shore power, Check the voltage across the house bank of batteries. See what the voltage is. I'm guessing 12.5. Could also be a bad connection somewhere in the 12 circuit (hopefully.) Good luck.

Here is what you want to see.
A fully charged battery, sitting on the bench with NO LOAD will be about 12.65V.

If you are connected to shore power, the minimum should be 13.8 which is a float charge. If the charger is actively charging, you should see about 14.2V (approx).

My guess is that your batteries have only been charging while you were driving and there is something wrong with the charger inside the inverter.

Regards,

Dan

WYRon · 03-13-2016, 06:38 AM

In terms of the generator stopping early, I can only say for my Magnum with AGS this is normal based on the time setting in the AGS menu. Even if it starts on low voltage, it will only run for the time programmed. For me, that is normally 1 hour, but I've had it up to 2 hours. Could also possibly be a problem associated with the "Quiet time" settings in the same menu.

pointrow · 03-14-2016, 05:20 PM

Up date: Moved to shore power and battery voltage jumped up to 14.1 and full bars for full batteries. On the road 13.5v the same as on generator. So the dc charging system is suspect.
FW thinks it is the Ohnan Generator at fault but why wouldn't the engine alternator charge the batteries full?

gemert · 03-14-2016, 05:31 PM

Quote:

Originally Posted by pointrow

Up date: Moved to shore power and battery voltage jumped up to 14.1 and full bars for full batteries. On the road 13.5v the same as on generator. So the dc charging system is suspect.
FW thinks it is the Ohnan Generator at fault but why wouldn't the engine alternator charge the batteries full?

The 120VAC that your inverter sees is from the transfer switch. At the input of the inverter there is no difference between shore power and Genny power. The output of the transfer switch either comes from shore or genny. With that said the answer may be in the setting of your magnum inverter as mentioned above. Run time setting or voltage or something. As to the other comment about resetting the inverter, you can do that by making sure you are not hooked up to either shore or genny power. Disconnect the negative cables on both battery banks, wait 5 minutes and reconnect them. That should reset the inverter. It does sound like the inverter itself is good. It has to be something in the controls for the inverter (says me the non-expert!) But the Navy did spend a lot of money to train me to fix electronic gear over 40 years ago. Good luck.

xflyer · 03-14-2016, 05:45 PM

Sounds like a bad ground. Get some spray electronic cleaner and check ALL the grounds in the system. Especially if your in a high humidity environment.

gemert · 03-14-2016, 05:54 PM

Quote:

Originally Posted by xflyer

Sounds like a bad ground. Get some spray electronic cleaner and check ALL the grounds in the system. Especially if your in a high humidity environment.

One more idea related to this. In the transfer switch there are two relays. One for the genny power and one for shore power. If the genny side relay had worn or corroded contacts...maybe. I really don't think it's something that is common to both the genny and shore power since there isn't a problem connected to shore. That leaves the transfer switch and control circuits or settings. Good luck, I hope we haven't added to your confusion. Good luck.

dpinvidic · 03-14-2016, 07:56 PM

Quote:

Originally Posted by pointrow

Up date: Moved to shore power and battery voltage jumped up to 14.1 and full bars for full batteries. On the road 13.5v the same as on generator. So the dc charging system is suspect.
FW thinks it is the Ohnan Generator at fault but why wouldn't the engine alternator charge the batteries full?

Still strange symptoms. The genny simply generates 120v power in place of shore power.
Your inverter also provides battery charging anytime 120v is present (genny or shore).

When you are on the road, the alternator charges ghe cgassis batteries.
The coach builder installs a solenoid (aux start) which ties the house and chassis batteries together when driving so they all charge.

Sounds like you have two problems.
Your complaint is tge house batteries dont charge on the road.
With the engine idling, meassure the voltage on BOTH chasdis and house batteries, they should be 13.8 or higher.

The other problem is thd genny. Meassure the 120v, is it 120v on both legs.
Maybe the transfer switch contacts are bad.

Regards,

Dan