Generator intermittently not charging batteries

[MattE303]

On our last trip with the Carbon, we noticed 2 new electrical issues that may or may not be related. First, the converter fan runs 100% of the time, even when not plugged in to shore power, and no draw from any 12 volt equipment. The dealer is assuming a bad thermal sensor is responsible and will check it at a service appt in a couple weeks.

The issue that really concerns me though, is that we noticed that the batteries didn't always charge when the generator was running. The first night I had the generator running for a couple hours watching tv, turned it off and went to bed. Woke up the next morning to a dead battery. The heater kicked on once or twice during the night, but didn't run long and definitely shouldn't have killed the battery. I had to hook up to the truck to charge the battery enough to be able to start the generator. After that, I started watching things closely and noticed that sometimes when the gen was running, the battery would show 2/3 or 1/3 instead of Full/charging like it normally does, and was actually draining if we used 12 volt lights and such (even though the gen was running).

I also noticed that when this happened, if I stopped the generator and restarted it, the battery level would show as Full/charging, so the problem seems to be intermittent.

Anyone seen this before? Any thoughts on what the issue might be, and could it be related to the converter fan issue?

[bobbecky]

I have no idea why the converter fan is running, but with your intermittent problems, it sure sounds like a loose 12 volt connection, maybe at the batteries, possibly a loose ground connection, but at least something is loose in your wiring. I didn't have problems like you are having, but when upgrading my batteries a couple years ago, I discovered loose connections in the area where the batteries are, just tight enough to not be burning, but barely finger tight. The batteries are installed by the dealer, so this wouldn't be a manufacturing problem, but would be on the dealer.

[JRTJH]

I'm making several assumptions here, but here goes.

First of all, have you verified that the battery cutoff switch is operational and all the connections on it are tight?

Now, I'm guessing you have an ONAN "onboard" generator and a 50 amp automatic transfer switch. You don't state in your description that you have 110 VAC power in the trailer, but I'd assume you do (watching TV, etc) so the assumption would be that the generator is putting out the appropriate voltage and the transfer switch is operating properly. If that is true, then "on to the next thoughts"...

Your power center is probably a WFCO 9900 series, 50 amp AC breaker/DC fuse/converter-charger unit.

Your dealer is wrong in stating that there is a "thermal relay" that controls the converter/charger fan. It is a "current controlled" fan. The more power that is demanded, the faster the fan runs. With that in mind, if the fan comes on immediately at full speed, that indicates that you have a load on the converter/charger that's calling for "max DC power". As a note: If the fan were "thermally controlled" it would not come on immediately, but would only come on after the transformer started to heat up.

My guess would be a shorted cell in the battery, a loose terminal on the DC power distribution panel (check all the screws to be sure the wires are securely tightened in place) or you have a shorted transformer in the converter/charger.

You can download the owner's manual for your WFCO 9900 series power center here: http://wfcoelectronics.com/wp-conten...ors-Manual.pdf

The "troubleshooting steps" on page 5 will pretty much "zero you in" on any problem with the power center, but my "best guess" would be a bad battery.

[MattE303]

Originally Posted by JRTJH

I'm making several assumptions here, but here goes.

First of all, have you verified that the battery cutoff switch is operational and all the connections on it are tight?

Now, I'm guessing you have an ONAN "onboard" generator and a 50 amp automatic transfer switch. You don't state in your description that you have 110 VAC power in the trailer, but I'd assume you do (watching TV, etc) so the assumption would be that the generator is putting out the appropriate voltage and the transfer switch is operating properly. If that is true, then "on to the next thoughts"...

Your power center is probably a WFCO 9900 series, 50 amp AC breaker/DC fuse/converter-charger unit.

Your dealer is wrong in stating that there is a "thermal relay" that controls the converter/charger fan. It is a "current controlled" fan. The more power that is demanded, the faster the fan runs. With that in mind, if the fan comes on immediately at full speed, that indicates that you have a load on the converter/charger that's calling for "max DC power". As a note: If the fan were "thermally controlled" it would not come on immediately, but would only come on after the transformer started to heat up.

My guess would be a shorted cell in the battery, a loose terminal on the DC power distribution panel (check all the screws to be sure the wires are securely tightened in place) or you have a shorted transformer in the converter/charger.

You can download the owner's manual for your WFCO 9900 series power center here: http://wfcoelectronics.com/wp-conten...ors-Manual.pdf

The "troubleshooting steps" on page 5 will pretty much "zero you in" on any problem with the power center, but my "best guess" would be a bad battery.

The battery cutoff switch definitely works, although I haven't taken anything apart to check the tightness of connections to it.

The generator is an onboard Onan 5500, there is 110 in the trailer and we've had no problems with it (TV, Microwave, air conditions, etc. all work).

We purchased the trailer new in April, so the batteries aren't old, although I did manage to run them all the way down a few times while parked at home (before I discovered the battery cutoff switch). It seems like the intermittent charging problem points at something other than the battery, although there certainly could be 2 problems, not just one.

I'll see if I can figure out how to access the converter to check for loose wires. To evaluate the batteries for any issues, do I just take them to an auto parts store and ask them to test, like you would do with a car battery?

[JRTJH]

Yes, you can just remove the batteries, take them to AutoZone, WalMart or most any other store that sells batteries and they can do a load test for you.

Essentially, as for your converter, when you remove the batteries, if you have a volt meter, test across the two battery leads (no battery installed) and you should get 13.6 VDC. If you do, your converter is working properly, if you don't, then start digging in compartments, behind false walls, etc until you find it.

It's been my experience with the typical "cheaply made group 27 deep cycle battery" that it only takes 2 or 3 "really deep discharges" to pretty much render them "core material"..... You might get lucky, but.....

[MattE303]

Originally Posted by JRTJH

Yes, you can just remove the batteries, take them to AutoZone, WalMart or most any other store that sells batteries and they can do a load test for you.

Essentially, as for your converter, when you remove the batteries, if you have a volt meter, test across the two battery leads (no battery installed) and you should get 13.6 VDC. If you do, your converter is working properly, if you don't, then start digging in compartments, behind false walls, etc until you find it.

It's been my experience with the typical "cheaply made group 27 deep cycle battery" that it only takes 2 or 3 "really deep discharges" to pretty much render them "core material"..... You might get lucky, but.....

Thank you John, I'll follow up when I know more...