Where/how to look for a short/broken connection

[snipsnap]

Hi everyone,

I'm stumped and need some ideas how to proceed. My battery (new last year) is not getting power and nothing works when unplugged from shore power.

When I'm connected to shore power, everything works in the camper, except 1) the fridge won't run off electricity (won't even give the option to switch to ac from gas) and 2) the battery cables don't show any power.

When I disconnect from shore power. Nothing works. Fridge won't even try turning on with gas. No lights. Nothing.

I can see there's ~13v at the converter to the battery but there is no reading at the white or black wires which connect to the battery.

I do see continuity from the battery leads to the converter but I think there's a short because touching white to black also makes the multimeter beep.

I have checked all fuses in the fuse panel, inline to the battery, tongue jack and even the three tube fuses behind the fridge. All show continuity.

I've opened up the junction box near the battery and besides the rat nest of wires, I don't see any pinched or stripped wires.

I'm not sure where exactly I should look or test next. Can anyone give me ideas on next steps?

Thank you

 

[OldWEB]

I assume you have a travel trailer with one battery, so you could bring in the battery and connect directly to the converter/fuse panel

 

[DonTom]

Hi everyone,

I'm stumped and need some ideas how to proceed. My battery (new last year) is not getting power and nothing works when unplugged from shore power.

When I'm connected to shore power, everything works in the camper, except 1) the fridge won't run off electricity (won't even give the option to switch to ac from gas) and 2) the battery cables don't show any power.

When I disconnect from shore power. Nothing works. Fridge won't even try turning on with gas. No lights. Nothing.

I can see there's ~13v at the converter to the battery but there is no reading at the white or black wires which connect to the battery.

I do see continuity from the battery leads to the converter but I think there's a short because touching white to black also makes the multimeter beep.

I have checked all fuses in the fuse panel, inline to the battery, tongue jack and even the three tube fuses behind the fridge. All show continuity.

I've opened up the junction box near the battery and besides the rat nest of wires, I don't see any pinched or stripped wires.

I'm not sure where exactly I should look or test next. Can anyone give me ideas on next steps?

Thank you

If there is no DC at the refrigerator, it will NOT work on ANY mode. It needs the DC for the control.

Best to mention what type of rig. The most common problem is probably corrosion on the battery cables if they are lead acid. If you can, take a photo of your house batteries and post it here.

IMO, most likely your problem is right at the battery box. Measure the voltage right on the battery cables when you do NOT have shore power. Troubleshoot with no shore power connected.


-Don- Redcrest, CA

 

[SpencerPJ]

Are you sure you have checked an inline fuse coming off the positive side, likely under the trailer? Might look like picture below, might be in another type box.

 

[bigbAZ]

I think there's a short because touching white to black also makes the multimeter beep.

That's because there is continuity from connected loads and from the battery itself. To check for shorts the conductors first need to be disconnected at each end and isolated. Doubtful there is a short between + & - or you would have melted fuses or a fire. As the others said, look for an open, not a short.

 

[gwinger]

Are you sure you have checked an inline fuse coming off the positive side, likely under the trailer? Might look like picture below, might be in another type box.
View attachment 1322619

Those are probably auto-reset breakers. They do fail.
There may be two of them.
Disconnect the battery and shore power and use an ohm meter to check them.
Should be 0 ohms.

 

[SpencerPJ]

Those are probably auto-reset breakers. They do fail.
There may be two of them.
Disconnect the battery and shore power and use an ohm meter to check them.
Should be 0 ohms.

Yes I had one fail, that's how I know about them.
OP: you also can short across them and see if the power comes on

 

[gwinger]

Yes I had one fail, that's how I know about them.
OP: you also can short across them and see if the power comes on

Only problem with shorting them, if you do have problem down stream, it may cause more damage.
Somewhere on the breaker, it should say what the amp rating is.

 

[Kirk]

1) the fridge won't run off electricity (won't even give the option to switch to ac from gas)

That is because your refrigerator uses 12V-dc to power the controls in either 120V-ac mode or in propane mode. With no power to the controls, nothing will work and it won't even turn on.

2) the battery cables don't show any power.

I am not sure what you mean by that. to check the battery cables for a voltage from the converter, you need to lift the negative cable from the battery and with your meter in the volts-dc mode, measure between them.

When I disconnect from shore power. Nothing works.

That tells us that you have no 12V-dc power available to anything.

When I'm connected to shore power, everything works in the camper, except the fridge won't

Have you tried turning on the lights? Did you try the potable water pump? Those are 12V-dc and would have power from the converter, via that fuse panel if it was working and had 120V-ac available to it.

I can see there's ~13v at the converter to the battery but there is no reading at the white or black wires which connect to the battery.

Are you measuring the 13V between the terminals on the output side of the converter? If so that means that the converter does work.

I do see continuity from the battery leads to the converter but I think there's a short because touching white to black also makes the multimeter beep.

In order to measure continuity for the leads between the converter and the battery, first disconnect 120V or unplug the converter so that it gets no power. Next you need to remove the leads from the battery, or whatever they connect to and measure the resistance (ohms) between each one and the terminal it connects to on the converter. A reading of 0 ohms or nearly 0 ohms indicates that you have continuity.

I'm not sure where exactly I should look or test next.

Is there any power to the fuse panel that you are checking fuses on? If not that is not helpful. Does the converter connect directly to the battery terminals and another wire than connect from the battery terminals to the fuse panel? Very often the converter is connected to the 12V distribution panel, and the battery is connected to the same point. You need to be very sure of where all of your readings are coming from. Are we correct that by camper you mean a travel trailer, and not a motorized RV? If you measure between the two posts of your battery with nothing connected to them, what voltage do you get? (When doing that you only need to remove the leads from one post.) If you do remove any leads, be sure to mark them so that you know where to put them back as that is a mistake that is very easy to make.

Let us know where you are in troubleshooting and we will help all that we are able.

 

[gwinger]

Here is a very simple diagram of how the converter works.
First, you have to verify that you have 12 volts coming out of the converter when plugged into shore power. If not, check for the 120 volts into the converter. If not, you may have a circuit breaker kicked.
If you have the 120 in and no 12 volts it may be a bad converter, but then, no 12 volt items will work on shore power, lights, water pump, bath fan, etc.
The problem with the fridge not running may be a blown 12 volt fuse. Don't count on a visual check of the fuses.
If you have 12v out of the converter, disconnect the positive wire on the battery and check for 12 volts on that wire to ground. (it may read 13+ volts+)
The positive wire to the battery is connected to the same source as the power to the fuses.
One other thing, what is the battery voltage with the cables disconnected?
It sounds like you may have two problems. A blown fuse in the panel and a bad relay going to the battery.
One thing that doesn't make sense, you say the white and black wires on the battery?? Should be black and red.
As far as the rats nest of wires near the battery, that may be the wiring for the 7 pin connector.

 

[snipsnap]

If there is no DC at the refrigerator, it will NOT work on ANY mode. It needs the DC for the control.

Best to mention what type of rig. The most common problem is probably corrosion on the battery cables if they are lead acid. If you can, take a photo of your house batteries and post it here.

IMO, most likely your problem is right at the battery box. Measure the voltage right on the battery cables when you do NOT have shore power. Troubleshoot with no shore power connected.


-Don- Redcrest, CA

 

[snipsnap]

Wow, lots of replies. Thank you everyone. I took another look last night and I'll try to give more info here:

Best to mention what type of rig. The most common problem is probably corrosion on the battery cables if they are lead acid. If you can, take a photo of your house batteries and post it here.

IMO, most likely your problem is right at the battery box. Measure the voltage right on the battery cables when you do NOT have shore power. Troubleshoot with no shore power connected.

The camper is a 2014 Radiance travel trailer. The batter is new last year and the cable connectors are free of corrosion. I've attached some photos below. With no shore power, I do not not measure any voltage at the cables going to the battery. With shore power is the same. A couple days ago the battery itself was reading around 8v, I left it on a trickle charger over night and it charged up to around 12v. I left it sit disconnected and checked yesterday and it still sits at 12v so the battery is good.

Are you sure you have checked an inline fuse coming off the positive side, likely under the trailer?

Yes I checked the inline fuse. It's a 30amp green fuse in a rubber housing. See pic. There's a 40amp fuse the a black rubber housing (seen in the background of the pic) which goes to the tongue jack. Both fuses are good.

Is there any power to the fuse panel that you are checking fuses on?

Yes, there is power going to the fuse panel. When on shore power, I see 120 going in and ~12v going out to the battery (I attached the wiring diagram).

In order to measure continuity for the leads between the converter and the battery, first disconnect 120V or unplug the converter so that it gets no power. Next you need to remove the leads from the battery, or whatever they connect to and measure the resistance (ohms) between each one and the terminal it connects to on the converter. A reading of 0 ohms or nearly 0 ohms indicates that you have continuity.

I don't have long enough wires on my multimeter so I took some bare wire I had lying around to connect to the battery leads. I connected to the bare wire and checked continuity to the battery out section of the panel. The multimeter beeped but also when I checked opposing polarities. (From the replies I see, I guess that would give me a false short reading as it could be caused by other things connected to the circuit.) That being said, would resistance still be zero with my janky workaround?

Have you tried turning on the lights? Did you try the potable water pump?

Yes, everything works are expected on shore power. Nothing runs when I disconnect shore power. This, and the voltage checks I did at the panel/converter, lead me to believe the converter is ok.

One thing that doesn't make sense, you say the white and black wires on the battery??

The wires leaving the converter to the battery are white and black, and match the battery wires (see pics). My fathers rig is the same way.

It sounds like you may have two problems. A blown fuse in the panel and a bad relay going to the battery.

I have checked every fuse I could find with the multimeter and they are all good. How to I check a relay?

Thanks again everyone for helping, I really want to solve this soon as we are camping next weekend

 

[bigbAZ]

1. Take another look at the battery, 12 volts is NOT charged, 12.7 after resting is charged (assuming lead acid). You can't assume the battery is OK just because it's only a year old, if it was allowed to get to 8 volts and left that way it could be damaged/failed. You could temporarily swap it for one from your car/truck to see if maybe there is a battery issue.

2. Is there a battery switch in the RV? Battery switches and their associated relays can fail. If the battery swap from #1 doesn't reveal anything try running a wire directly from the battery + to the converter + battery terminal. If still no power with a verified good battery next do the same with the battery negative.

The above process of elimination steps will greatly speed up the troubleshooting as you won't be wasting time on stuff that is good and it will lead you right to the problem area. You only have 3 basic sections, battery, converter and wiring/switch/relay between them. Find out what it isn't and you will be left with what it is.

 

[snipsnap]

1. Take another look at the battery, 12 volts is NOT charged, 12.7 after resting is charged (assuming lead acid). You can't assume the battery is OK just because it's only a year old, if it was allowed to get to 8 volts and left that way it could be damaged/failed. You could temporarily swap it for one from your car/truck to see if maybe there is a battery issue.

2. Is there a battery switch in the RV? Battery switches and their associated relays can fail. If the battery swap from #1 doesn't reveal anything try running a wire directly from the battery + to the converter + battery terminal. If still no power with a verified good battery next do the same with the battery negative.

The above process of elimination steps will greatly speed up the troubleshooting as you won't be wasting time on stuff that is good and it will lead you right to the problem area. You only have 3 basic sections, battery, converter and wiring/switch/relay between them. Find out what it isn't and you will be left with what it is.

Thanks for the reply, just to add/clarify, I'm using an analog multimeter (not digital) so when I say 12v it's could be 13 as it's hard to see exactly where the needle lands.

I will try what you proposed this weekend; just need to find a length of decent wire.

Regarding the battery switch, I have a pull switch/knob which is a battery bypass. I didn't think of that going bad (duh!) Could I bypass that switch with a wire across the + and - or would that just emulate a battery disconnect? Also, regardless of the switch's position, should the battery not charge (assuming it's good) when connected to shore power?

 

[bigbAZ]

Thanks for the reply, just to add/clarify, I'm using an analog multimeter (not digital) so when I say 12v it's could be 13 as it's hard to see exactly where the needle lands.

I will try what you proposed this weekend; just need to find a length of decent wire.

Regarding the battery switch, I have a pull switch/knob which is a battery bypass. I didn't think of that going bad (duh!) Could I bypass that switch with a wire across the + and - or would that just emulate a battery disconnect? Also, regardless of the switch's position, should the battery not charge (assuming it's good) when connected to shore power?

Yes, bypass the switch if it is suspect! No the battery will not charge when plugged in if the switch is off or bad. The same wire that brings 12 volts into your trailer from the battery carries the charge current from the converter back to the battery when plugged in and it goes through the switch in either direction, so with the switch on and the RV plugged in it should charge, switch off or bad it won't charge.

edit: If it's just a manual battery disconnect there won't be a + or - and only the + wire will be connected to it. Battery switches with relays use the negative but not manual ones.

 

[DonTom]

I see a black wire on the battery positive. Where does that wire go?

-Don- Redcrest, CA

 

[bigbAZ]

I see a black wire on the battery positive. Where does that wire go?

-Don- Redcrest, CA

I'd bet a weeks pay it goes to the push/pull battery switch and from there to the bottom "B+" terminal on the converter.

disclaimer: I am retired

 

[bigbAZ]

BTW if it's the battery switch and it's manual there are many different manual battery disconnect switches available that you could retrofit. If it uses a relay that becomes a bit more complicated but still doable.

It would be a good idea to verify which type of switch it is to avoid improper testing/bypass procedures, can you post pics of the front and back?

 

[snipsnap]

BTW if it's the battery switch and it's manual there are many different manual battery disconnect switches available that you could retrofit. If it uses a relay that becomes a bit more complicated but still doable.

It would be a good idea to verify which type of switch it is to avoid improper testing/bypass procedures, can you post pics of the front and back?

I'm at work right now but I'll confirm when I get home. However, looking quick online I think this is the one. If not, it looks near identical to the one I have.

 

[bigbAZ]

I'm at work right now but I'll confirm when I get home. However, looking quick online I think this is the one. If not, it looks near identical to the one I have.

Yep that one is strictly manual and easily bypassed or replaced. To bypass you can just bolt the two wires together and tape them up, or put them both on the same terminal if room.