Battery Power Issues

[Matt from NE]

I can't get any of my interior lights, porch light, or water pump to work on battery power.

Here's what I know:
1. Everything works on 120AC
2. a.The battery is fully charged and all cells are good.
2. b. I believe that the 120AC IS charging the battery.
3. the fuse coming off the battery positive is good.
4. all fuses inside are good.
5. This is a 2007 Jayco Jay Series

[JimD]

You stated that you BELIEVE the battery is being charged. That gives the impression that you didn't measure it with a voltmeter. If you don't have a voltmeter now is the time to get one.

Common items that knock out 12 volts:

1. Loose, broken or corroded ground cable connection to the frame.
2. Battery disconnect switch engaged. Could be stuck in off position if button held in for more than a second or two.
3. Inline fuse from the battery bad.
4. Bad battery.

The first check is to verify the battery has good voltage (voltmeter) without being plugged in. It could be bad and the charging when plugged in is masking it.

[Matt from NE]

1. Loose, broken or corroded ground cable connection to the frame.
Checked. clean and secure.


2. Battery disconnect switch engaged. Could be stuck in off position if button held in for more than a second or two.
This switch is in the roof. It has recently been replaced. It kills power to the ceiling lights weather plugged into shore power or battery power. It works fine with shore power.


3. Inline fuse from the battery bad.
Fuse has been checked with a multi-meter.


4. Bad battery.
Battery has been tested it has a full charge (more than full) and all cells are good.

You mentioned checking to make sure I'm getting power to the battery from shore power with a multi-meter, do I just put it on the leads from the battery and look for 12v DC to be feeding the battery?

[JimD]

Yep, just put the meter leads across the battery. A good battery that is not being charged will measure in the mid 12s. A battery that is being charged will read mid 13s to mid 14s depending on what charge mode is currently active.

Good luck.

[Matt from NE]

I just put a meter across it. 12.59
The battery was tested yesterday at my local auto parts store and they assure me the battery is in great condition.

What next?

[JimD]

Ok, we will use metal ground for most of the tests. Touch the black meter lead to a metal ground and the red lead to the positive post on the battery. This should verify the battery ground is connected and working (at least mostly).

Now follow the positive battery cable and see where it goes to first. It most likely will feed an inline fuse or circuit breaker. Measure from each connection lug to metal ground. Both sides should measure battery voltage to ground. If one side does but the other side doesn't, you've found the problem. Fuse or circuit breaker is bad.

If that test proves ok, follow the positive cable to the next thing inline which may be the disconnect solenoid and do the same tests to both big lugs on the solenoid.

Hang in there, you will eventually find the problem.

[Beagle lover]

Have them perform a load test, batteries can read 12.87 volts but fail miserably under load.

[JimD]

Originally Posted by Beagle lover

Have them perform a load test, batteries can read 12.87 volts but fail miserably under load.

Instead of doing a full fledge load test, you could take the lazy approach (my way of doing things sometimes). Just place your meter across the battery and turn on a few 12 volt items while watching the meter. If it remains steady your items aren't being connected through, which is what I think you are fighting. If any item turns on and the battery goes way down, then the battery is suspect.

As Beagle lover mentioned, a load test is good but until you can get something to connect to the battery, it may not yield the info you are looking for.

Side note - had a beagle growing up. Sure miss those floppy ears.

[johneliot]

The fuses may be good but did you check to see if you’re getting power across each fuse plug?

[Matt from NE]

The circuits all work under AC power. I assume there is power across them.

[johneliot]

Putting a tester across the fuse slots will tell you if the converter is working on the DC side. It’s just a part of trouble shooting.

Edit: I mean just when you have the battery hooked up and the trailer unplugged.

[JFlightRisk]

If your positive cable from the battery goes into a junction box on the frame, take the cover off and check for any bad connections. Household wire nuts are commonly used and are susceptible to corrosion since OE junction boxes are not waterproof.

When I was changing ours out to a Pollak waterproof box a few years ago I found corrosion starting on the ground wires when I took the wire nut off. Something else for you to check and maybe eliminate in your search .

[jimmoore13]

Please clarify one thing.

Do your 12 volt systems work when connected to shore power? If so, the converter/charger is supplying the power...not the battery. 12 volt systems in an RV will work even if the battery is disconnected...so long as you are plugged into shore power.

If your 12 volt systems work while connected to shore power, that substantially narrows the possibilities on what might be wrong.

I know fuses have been discussed, but there are two ways to test a fuse reliably:

1. Multimeter continuity (ohms) test.
2. Pull the fuse and shine a flashlight through it from behind.

The main fuse/breaker on the tongue may have been tripped. A fuse must be replaced. A breaker MIGHT be able to be reset. But these things live in a harsh environment, so don't be afraid to replace the breaker. BTW, if the fuse is blown or the breaker tripped, be prepared to determine why.

Something else you can do with a multimeter is test the battery voltage when connected to shore power. The converter/charger should be sending considerably more than 12.59 volts to the battery when connected. Voltage should be in the 13.2 to 13.5 range. If your battery is effectively disconnected from your rig, the fact that its is not DISCHARGED doesn't mean much. Not losing charge is a "symptom" of not being connected to anything. Batteries will hold charge for a long time if they are healthy and fully charged when disconnected. But when plugged into shore power, the battery voltage reading at the battery should be over 13 volts...even if the charger is only sending a maintenace charge CURRENT...as a multi-stage converter/charger will do. Repeating: if your voltage reading at your battery while connected to shore power is 12.5, your battery may be disconnected from the rig...in one way or another...positive or ground.

This thread is pretty long, and many have offered ideas. These are things I would check if you haven't already.

[toxictom]

Look for a switch on your converter that switches from 12vdc to 110vac. Switch it to battery.

[Matt from NE]

I just did this. No continuity across the fuse terminals. What next.

[Matt from NE]

Originally Posted by johneliot

The fuses may be good but did you check to see if you’re getting power across each fuse plug?

I just did this. I’m not getting continuity across the fuse terminals. What’s next?

[johneliot]

The next thing I would try is to trace the pos/neg wires from the battery to where they hook into the converter. This should tell you if the power from the battery is making it to the converter.

[Matt from NE]

Originally Posted by johneliot

The next thing I would try is to trace the pos/neg wires from the battery to where they hook into the converter. This should tell you if the power from the battery is making it to the converter.

Can’t figure out how to imbed a photo. This is what the schematic looks like.

www.facebook.com/share/bB2nWjwvBZhvqjgt/?mibextid=WC7FNe
Where to where?

[johneliot]

I don’t do facebook so I can’t access that link.

[Matt from NE]

Does this help?