12V Power Issue

[tramponi]

I am having an issue with my 12V power when I am just trying to run off the battery. None of my lights or any 12V items (jack, stabilizers, slides, etc) will operate. When I hook up to shore power/generator, all these items work fine. I checked the voltage on the battery with a multimeter and it is around 12.4V. Searching the forum I see the issue may be due to the 12V dc circuit breakers needing to be reset or replaced. I will try that next weekend when I am at the trailer as I hope that is the issue.

On my wiring, there is also a second type of device with a zip tie around it that is just suspended between two wires. See the attached picture. The main power from the battery goes to the circuit breaker block mounted on the trailer frame and then the wire coming off (orange wire) goes to this zip-tied device. I have attached a picture of it. I am not sure where the black wire with yellow connector goes after this device.

Is this also a type of circuit breaker or is it something else? It looks much thinner than the circuit breaker mounted to the frame and also has some type of plate on the back of it. Not to mention the zip tie also. All the help is greatly appreciated in identifying what this is.

Thanks!

[Bama Rambler]

That piece looks like it used to be a breaker that somebody wire-tied a shorting bar to. I'd replace both of those devices with proper breakers.

[tramponi]

With the age of our trailer, I am afraid I may not be able to determine the Amp rating of the circuit breakers. Looking online, I see them anywhere from 10Amps up to 50Amps. Is there a standard size that is used or recommended for use in most travel trailers? Or if they aren't labeled, is there a way to find the rating of the current ones?

[CHICKDOE]

my guess would be that they are (or were at some time) 12 volt circuit breakers. it looks like the cable from the battery does to the frame mounted device. there are several cables going to loads on the other side of the frame mounted breaker. the short orange cable takes the battery power and routes it to the zip tied breaker. this breaker protects some other load.

take some voltage readings at each terminal of the two breakers to see if they are conducting the battery power through them. one, or both, probably are not. do this when not connected to shore power so you are measuring battery power only.

[Blackrock]

Gauranteed that wiring needs a cleanup. As for that circuit breaker a 20A will probably work. For corrosion like that I use PB Blaster.

[chriscowles]

I assume those breakers on your Rockwood UltraLite are just inside the trailer frame at the end of the trailer 7-pin cable. They are proper breakers for their purpose but are in bad shape. I'd replace them.

One breaker should be connected to the battery on one pin with 8 gauge wire, the other pin of the same breaker uses 8 gauge wire to connect inside a nearby junction box. That breaker will have a small black reset button and protects the long 8 gauge circuit back to the power center against short or overload.

The same breaker will have a wire acting as a jumper to another breaker. That jumper wire should be on the post with the 8 gauge wire going to the junction box. It should not be on the post with the battery.

The second breaker is a different type, i.e., it's self-resetting. The loads it serves are usually the slide-out and power jack motors. Those loads are high-current, usually off, and operate for only short intervals. The breaker will trip if operating either draws too much current which risks overheating the wire, but it will reset itself after it cools off.

The last picture is an annotated diagram of those breakers and junction box on my 2020 Rockwood Mini-Lite. (The manual type II breaker is mislabeled as type 3, which includes a push-to-trip button.) I also included links to example breakers. The auto-reset breaker (without the button) is referred to as a Type I; the manual-reset breaker (with the button) is referred to as Type II. (A Basic Guide to Circuit Breaker Types)


Fastronix 40A 12V Type 1 Automatic Reset Circuit Breaker (Amazon link)


ZOOKOTO 12V/24V Stud Bolt Type Manual Reset Circuit Breaker 40A with Cover (Amazon link)


Cooper / Bussmann CB185-60 Circuit Breakers 60A Type 3 breaker



Diagram of Mini-Lite junction box. (The Type II breaker is mislabeled as Type 3.)

[chriscowles]

Originally Posted by tramponi

With the age of our trailer, I am afraid I may not be able to determine the Amp rating of the circuit breakers. Looking online, I see them anywhere from 10Amps up to 50Amps. Is there a standard size that is used or recommended for use in most travel trailers? Or if they aren't labeled, is there a way to find the rating of the current ones?

There is not a "standard size". The breaker size is determined by the wire it protects. That said, Rockwood typically uses 8 AWG wire from the battery to the junction box, and further on to the power center. It should have a 40A manual-reset breaker. The secondary breaker (a jumper from the 40A) probably is connected to slide and jack motors with 10 AWG wire. Assuming so, it should use a 30A auto-reset breaker.

[Bama Rambler]

I agree with Chris, They're probably 40 and 30 amp units.

[tramponi]

I bought a 40amp and 30 amp breaker and installed them with no issues. Everything works as it should. Thanks for all the help!