Wiring Question

IchLiebeBier · 11-17-2019, 08:03 PM

Hi all,
Our last trailer only had one battery wire for positive and one for negative connecting to a single circuit breaker.

The current trailer has two each, with the positives each connecting to its own circuit breaker. When we bought it, it came with one battery, and both sets of wires were attached to the battery.

I have a Wirthco 4 way switch, so if I upgrade to two batteries, should I wire the batteries like in my diagram, and just switch it to batteries 1+2 all the time? Or would you recommend an alternate wiring?

Thanks.

Site Team Note:
OP requests members disregard diagram -- superseded below.

**Bama Rambler** · 11-17-2019, 08:44 PM

What you propose is fine. There's not much reason to separate the batteries on your RV, but if you have a battery go bad you can isolate it from the other one until you get it replaced.

IchLiebeBier · 11-18-2019, 04:35 AM

thanks Bama

IchLiebeBier · 01-20-2020, 04:30 PM

OK, so I went to install the switch so it would be ready for camping, and I realized the wiring was not at all like I thought it was. The diagram above is completely wrong, so please disregard it. I didn't crawl under there until now, so I had to come up with a new wiring plan. I didn't realize the breakers were jumpered together.

Turns out, I have a pos/neg 6 AWG grouping for the trailer electronics; and a pos/neg 4 AWG grouping that I believe goes directly to the inverter. I did a lot of testing on it, and I believe that is correct. I couldn't physically see the connection due to the wires disappearing into the trailer body. But I'm pretty confident that's the way it's wired.

So, the only way I can figure out how to wire it is shown in the attached pic. I will run the batteries in parallel and attach to only the switch 1 position. Since the inverter has its own ground, I figured connecting them independently to switches 1 and 2 would isolate the batteries. Whichever battery got the inverter ground would drain faster than the other, even if the switch were set to "1+2". I think that's right anyway.

So, 2 questions:
1. Does this look correct? Should I connect the the switch wire to Battery 1 positive and the two grounds to the Battery 2 Neg?
2. Should the cable from the switch to the battery, and the cables between batteries all be 4 AWG? Or should I step it up to 2 AWG?

Thanks in advance.

babock · 01-20-2020, 04:33 PM

You need a fuse going to your inverter.

bubbles · 01-20-2020, 04:42 PM

Forget the fuse to the inverter what about that dead short to ground thru the fuse, if those are fuses. Do you not know what a fuse is for? Maybe I'm seeing something that isn't there.

IchLiebeBier · 01-20-2020, 04:59 PM

Quote:

Originally Posted by babock

You need a fuse going to your inverter.

I assume there is a fuse to the inverter since it was installed by the dealer. The positive wire that connects to it says "connect to battery positive" on it. But now that you mention it, if there is one, I wouldn't be able to get to it easily. I'll need to check that they installed it correctly.

As it is, I made no change to the way it was installed.

IchLiebeBier · 01-20-2020, 05:04 PM

Quote:

Originally Posted by bubbles

Forget the fuse to the inverter what about that dead short to ground thru the fuse, if those are fuses. Do you not know what a fuse is for? Maybe I'm seeing something that isn't there.

Those aren't fuses. I think they're circuit breakers (see picture of them in the first post). I guess they do look like blade fuses in my picture.

So I guess I do know what a fuse is for

bubbles · 01-20-2020, 05:53 PM

Quote:

Originally Posted by IchLiebeBier

Those aren't fuses. I think they're circuit breakers (see picture of them in the first post). I guess they do look like blade fuses in my picture.

So I guess I do know what a fuse is for

So, is the wire you show from one of the CB's going to the same chassis termination as the battery or chassis electronics? I'm not trying to be a sa but just trying to help you correctly interpret how the existing interconnects are made and maybe it really doesn't matter as you seem to have a handle on things.

dward51 · 01-20-2020, 06:48 PM

That right hand breaker in post #4's drawing is still a dead short to ground path to the chassis. That diagram is no where near correct. What exactly are you trying to do again?

IchLiebeBier · 01-20-2020, 07:26 PM

OK, I don't remember for sure where the black wires from the circuit breaker go. I think they go to the frame, but I don't want to give the wrong info.

If you look at the top pic in the first post, you can see the circuit breakers (if that's what they are. I assumed that's what they were, but I could be wrong).

The 4 AWG negative goes up through the body, and a different type of negative wire comes out of the inverter and also disappears into the body. I assume they are tied together out of sight.

The 6 AWG negative goes to a terminal block connector on the frame. I don't think the wires from the circuit breaker go to it.

What am I trying to do:
I want to have two batteries hooked up for boondocking. Plan to get LiFePO4 batteries. My initial plan was just to wire each battery to a separate post in the switch and set the switch to "1+2". But since I realized there are 2 pairs of pos/neg cables (one for inverter), I decided against it. If I do it the way I had planned, each battery would get a pos and a neg cable. But one battery would drain quickly due to the fridge, while the other wouldn't. Therefore, I want to run the batteries in parallel and hook to switch 1. that way they'll drain together.

Does that make sense?

As far as a dead short, I have no answer to that. The wiring has not been changed from the way it was delivered (except I want to add the switch). The circuit breakers have not been touched.

So the setup right now was that both positives and both negatives were attached to a single battery. The negatives are as shown. One positive comes from the inverter and one comes off the circuit breaker.

I hope this makes sense.

bubbles · 01-20-2020, 08:55 PM

Quote:

Originally Posted by bubbles

So, is the wire you show from one of the CB's going to the same chassis termination as the battery or chassis electronics? I'm not trying to be a sa but just trying to help you correctly interpret how the existing interconnects are made and maybe it really doesn't matter as you seem to have a handle on things.

I was wrong.

IchLiebeBier · 01-20-2020, 09:29 PM

Quote:

Originally Posted by bubbles

I was wrong.

You know what...keep your smart comments to yourself.

If I understood wiring, I wouldn't have posted the question here. I can always count on someone like you trying to prove how smart you are. You might want to take some motrin for that arm pain from patting yourself on your back.

If you don't have anything constructive to add, go somewhere else.

I'll stop short of telling you how i really feel, lest I be banned from the site.

But clearly you're not as smart as you think you are. Otherwise, you would have told me how it should be done. But...crickets.

Rick the Rocket · 01-20-2020, 09:46 PM

OP...It seems to me that the simplest method would be to leave the original connections as are. Then add the 2nd battery in parallel to the original setup. The occurrence of a battery going bad should not be very often, just disconnect the batteries and reconnect the good one. Once the dual battery setup is in place you can consider modifying it to incorporate the switch. Use cable heavy enough to carry the load of both original feeds for the parallel jumpers.

babock · 01-20-2020, 09:52 PM

Quote:

Originally Posted by IchLiebeBier

I assume there is a fuse to the inverter since it was installed by the dealer.

OK...didn't know that and its not shown on your diagram like the 2 circuit breakers which were installed already by the trailer manufacturer.

dward51 · 01-20-2020, 10:41 PM

Can you post a photo of what you have instead of the drawing.

Nothing from a circuit breaker or fuse should *EVER* go to the frame or ground. That is a dead short to ground condition and will instantly trip breaker or blow fuse. There should not be a circuit breaker or fuse on the negative line either, only in positive. Another thing to remember is just because a wire is black or white does not mean it is positive or ground. They seem to often use what is on hand in trailers with no rhyme or reason, so trace and test each run with a volt meter to verify what it actually is. A lot of units have red and black wire for positive and negative from the battery, but then switch to black for positive and white for ground/negative in the trailer. Mine has red and white from the battery but switches to red and also black for positive and white for negative in the trailer.

Two batteries in parallel are easy, no matter what type the wiring is the same. Parallel keeps the voltage at 12v and combines the amp capacity of the two batteries. You would need a DC breaker sized to the biggest load *AND* the wire gauge from the batteries (breaker protects the wire from melting and catching fire in a serious overload or short). It depends on the length of the wire run also. You also need to consider that on one leg of your wiring it drops to 6 gauge wire. Here is a Bluesea chart of breaker size vs wire gauge/length of run:

I would put put a breaker sized for the run and 4ga line between the batteries and the inverter. Also make sure the existing breakers match with the wire gauges. The only one I would not worry about is the break away switch, as it should *NOT* even be on a breaker or fuse, but it will pick up the power from the hot side of one of the existing breakers.

Not sure if this will be the same as yours, but this is my breaker setup on the tongue of my trailer as it came from the factory with a drawing. This may help you make sense of yours. The orange wire goes to the slideout motor. Note that all 4 of the terminals on the 2 breakers are "hot" positive 12v.

Jay2504 · 01-20-2020, 11:52 PM

dward 51, thanks for the chart of wiring size. IIRC you said that the converter on your unit is clear in the back? If that’s true the wire that runs to the converter is way too small IMHO. I believe that it is #6 like mine was. Run an additional #6 wire from the converter to the batteries and another #6 to ground on the frame at both ends of the camper. That will dramatically improve the battery charge rate. I also like the idea you had for a AGM under the dinette seat. Jay

IchLiebeBier · 01-21-2020, 05:16 AM

dward1,
Thanks for the info. That helps a lot.

I don't have a photo of the setup. There's nothing installed yet. I was asking in advance before I did anything.

I wanted to add a switch to the outside so I could completely turn off the batteries when it was parked. As it is now, there is a built in plastic switch key in the storage compartment, but the power jack stays hot. The last time I had it parked for a couple of months, the battery was drained completely.

I wouldn't replace the existing cables going to the camper or the inverter. I would only add a connecting wire from the switch to the positive of battery 1; as well as the cables from battery to battery for the parallel. The length from the switch to the battery 1 would only be about 18" or so.

I think the drawing of the circuit breakers you have is probably accurate to mine. I saw the three black wires coming off the circuit breaker and near it is a group of wires grounded to the frame. I thought they were the same, but obviously not. It is stupid to use black wires for hot. Confuses people like me. That's why I wasn't sure if they were circuit breakers. Didn't make sense to me to be grounded like that.

I've spent the last 25 years supporting combat operations, yet I still can't get a handle on simple electricity. It scares me a bit to mess with it.

But I truly appreciate folks like you who actually take the time to help someone out when they ask a question. Thanks.

**Bama Rambler** · 01-21-2020, 09:02 AM

The only thing I see wrong in the diagram in post #4 is the black wire from the fuse/breaker to chassis. While the wire from the battery to the fridge inverter should be fused, the inverter should have onboard fuse(s) so it's not the end of the earth.

IchLiebeBier · 01-21-2020, 11:14 AM

Quote:

Originally Posted by Bama Rambler

The only thing I see wrong in the diagram in post #4 is the black wire from the fuse/breaker to chassis. While the wire from the battery to the fridge inverter should be fused, the inverter should have onboard fuse(s) so it's not the end of the earth.

Bama,
I'm pretty sure I misidentified that black wire. It probably goes to the stabilizer jack or breakaway. I didn't think to trace it because it was black and I was focused on the 2 pairs of positive/neg cables.

So, if the thing is NOT grounded, everything looks ok to you?

Thanks.

You may also like: