Trailer batteries not being charged by TV while under way

[DavePhelps]

This is a new development. I don't like to travel with my propane on, and have always traveled with my fridge (Dometic 3 way) in DC mode. Up until now, I have always arrived at camp with 100% trailer batteries (I have the two 6v AGM's in series) and a cold fridge. This last trip, when I got home, there was a pulsing noise from out of the black box located behind the lower access/vent panel for the fridge. When I turned on the overhead lights in the trailer, they pulsed in sync with the refir. Batteries were down to 74%, and fridge was up to 40 degrees.

After checking all the fuses I could locate (all good) I took my multimeter and checked the 7 pin plug on my TV, which read 14.43 V, so that is not the problem.
With the trailer now plugged in to 120V ac, batteries charged right up to full pretty fast (13.68V after resting). I then checked the fridge on AC, no issue. Then on DC, no issue, and no pulsing noise anymore. Then on propane, no issue. Somewhere, between the trailer's 7 pin connector and the trailer batteries, there is a problem, the batteries are not being charged. My Elite is a 2015 model and I hear that the charge wire from the 7 pin plug goes straight to the batteries, but not sure. Anyone know the color? I've seen diagrams where it is black or red.... There is a black wire coming off the batteries but it seems to go to my Blue Sky charge controller. Thought I'd ask here first before calling Oliver. Also, being new to DC systems, I assume it is best practice to disconnect the batteries, and the solar input before diving in to the system?  Of course, I'd disconnect the AC as well! Thanks for any ideas, always appreciated.

Dave

[Galway Girl]

I have a 2019 and there is a re-settable fuse between the 7 pin and the +12v buss.  You may see if yours has one.

here is a pix showing the 7 pin line

[DavePhelps]

Thanks Galway Girl, but my system is much different from yours. It has similar fuses and busses, but not much else looks familiar.
I guess I'll need to call Oliver. None of the fuses have tripped. Will have to keep digging on this.....

Dave

[jd1923]

13 hours ago, DavePhelps said:

Thanks Galway Girl, but my system is much different from yours...

Dave, our hull may be closer to yours, #107 vs #113. I actually disconnected mine since we stay hitched on many single overnights and when boondocking on a mountain site for safety. Don't want to drain the TV! Generally, our solar covers the amp draw of our fridge on DC or at times we could use about 6% while driving a longer day.

Check the pic and look for the black wire disconnected on the left. Of course, test for voltage with and without connection to the TV or other 12V source. No 12V here and it might be hard to find along the path. First thing I would check is to open the 7-way connector on the Oliver side and see if you have continuity front to back. These connectors often get fried from corrosion. Sorry for the delayed response, just finished a busy week.

 

Edited May 24 by jd1923

[DavePhelps]

17 hours ago, jd1923 said:

Dave, our hull may be closer to yours, #107 vs #113. I actually disconnected mine since we stay hitched on many single overnights and when boondocking on a mountain site for safety. Don't want to drain the TV! Generally, our solar covers the amp draw of our fridge on DC or at times we could use about 6% while driving a longer day.

Check the pic and look for the black wire disconnected on the left. Of course, test for voltage with and without connection to the TV or other 12V source. No 12V here and it might be hard to find along the path. First thing I would check is to open the 7-way connector on the Oliver side and see if you have continuity front to back. These connectors often get fried from corrosion. Sorry for the delayed response, just finished a busy week.

 

 

So the black wire you disconnected is the charge wire from your 7pin plug? This is what I have pretty much determined for mine. To check this, I disconnected the trailer batteries, shut off the solar, disconnected shore power, and plugged the 7pin into my TV. Multimeter showed 14.51 V at the bussbar. I didn't disconnect the black wire from the buss for the best test, but am pretty sure that black wire is the 7pin charge wire. Hopefully you agree! This leaves me a little stumped as to what my refir problems are now. Since my batteries are now 9 years old, I may get them load tested. Also, while checking the 30A in line blade fuse that protects the wiring for the refir's DC heating element, it pulled out broken. That could have been me as it was hard to pull out, but maybe a bad fuse was the issue. Have since learned that you can check those fuses for continuity without pulling them....  So there is more to work out. It might take another trip to see if it happens again. In the meantime, I'm learning a lot about my electrical system! Thanks for your response.

Dave

[DavePhelps]

Went back for another look and my setup is very similar to JD1923, minus all the inline fuses.
This time I disconnected the black wire from the buss and retested with all power sources disconnected except my TV.
That black wire tested 12.8V with my engine off and 14.5V with engine on. The buss was dead. So that mystery is solved at least.
The crimp on that wire connector was pretty awful. I hope Oliver has upped their game with those. Onward.

Dave

 

 

[jd1923]

6 hours ago, DavePhelps said:

So the black wire you disconnected is the charge wire from your 7pin plug?

Multimeter showed 14.51 V at the busbar. I didn't disconnect the black wire from the buss...

Since my batteries are now 9 years old, I may get them load tested...

Also, while checking the 30A in line blade fuse that protects the wiring for the refir's DC heating element, it pulled out broken...

In the meantime, I'm learning a lot about my electrical system!

I'll parse your Qs one at a time...

You should really disconnect that wire. I forgot where I connected to ground but be certain that it's on/off connecting the 7-way plug. It's hard to know in the complex Oliver wiring systems that you are not getting feedback current.

The 14.5V reading shows you have a secondary power source still connected unless you had the truck running as only the alternator could achieve this voltage. Check voltage at the truck battery and you should see closer to 12.6V (or more just after charging) on a good lead-acid starter battery.
Addition: in your next post you wrote, "That black wire tested 12.8V with my engine off and 14.5V with engine on." Now you got it, this is perfect.

Wow, 9-year-old LA batteries! Load test? Maybe just replace them. First rule in any automotive electrical issue is starting with good batteries. Prior owner replaced ours 2-3 years ago with LA again. I would not want to travel far from home with your house batteries as it gets expensive to purchase batteries just anywhere. I'm assuming LA batteries on a 2015. If LiFePO4, you may have some life. If not, perhaps it's time for the LiFePO4 upgrade. Check our Epoch batteries.

Now I'll learn from you on this one. Where is your 30A inline fuse for the fridge? BTW, the 3 inline, yellow-jacketed fuses in my pic are for the 3 levelers which draw considerable current.

With each issue and upgrade, we all learn more about our Oliver electrical systems! Problem is OTT changed things at will year to year, if not hull to hull. More standardization on the newer hulls. There are no schematics and the closest electrical diagram I've seen is for a 2018.

Another BIG obstacle is having electrical components the length of the streetside basement, with the pantry and hull below blocking access and vision to make sense of the whole thing. I added the EMS that was not optioned on ours and learned a bit from that. I'm only one year into this (Chris' Birthday, June 7 will be our anniversary)! I believe when I upgrade to LiFePO4 in a year or two, I should have most of it figured out. Sure will, when I upgrade our inverter too. 😂 Glad I could help!

[jd1923]

Just remembered how I tested the black 12V wire. No TV connected, just check at the plug. Use a voltmeter or 12V test light and connect the black 12V to the ground at the plug. It should show the voltage of your house batteries (light ON). Disconnect the black wire on the busbar, as shown in the picture, to produce an open circuit and it should read 0V (light OFF). 

Remember whenever the 7-way plug is inserted into the TV, you always have this connection. Current will move either direction, from high potential (voltage) to low. OTT recommends removing the 7-way plug whenever parked for a period of time, certainly when camping overnight. I do not want to do that, as we often stay hitched and what if you forget? Less setup/tear-down checklist items the better!

 

One evening prepping dinner, our fridge somehow got switched to DC. Operating that panel is NOT straightforward! I woke at sunrise to find our 450AH LA house batteries down to 63%! Sure glad the TV starter batteries were not affected, or we would not have been able to break camp and drive off that morning! We also want to switch to DC when towing. This time we had to pull away with LP on. I have our black wire always disconnected, labeled and taped below to the insulation of another wire so not to hit ground. Our solar generally produces enough +Amps to cover the need, or when cloudy we arrive at 94% +/-.

[DavePhelps]

Thanks JD for all your input. My batteries are the Lifeline AGM's and they have been great. In fact, I may just replace them with the same when the time comes as they have completely met our electrical needs over the years and have some advantages over the lithiums like cold weather charging, TV charging, and cost!

The 30 amp automotive fuse for the fridge's  DC heating element is seen when you remove the lower fridge vent/access cover. It's green as you can see in the pic below.
Inside the black box on the left are two cartridge fuses: a 5A ac heater element fuse and a 3A control system fuse.

We bought a fridge button guard from RV Widget Works as it is very easy to bump into those fridge selector buttons and change a setting. Happened to us a few times and since putting the guard on, no problems. http://www.rvwidgetworks.com/Photo-Gallery.html

Thanks again for your tips and insights.

Dave