Excessive voltage drop... time to deal with it

[Persistent]

There is no need to replace the grounding lugs unless you can detect a voltage drop across the connection. Corrosion such as is shown in your picture is normal. Replacements will look the same in one or two years. Set your DC voltmeter on low voltage setting and measure voltage drop from the wire to the frame. You may need to clean a bare spot on the frame to get a good connection. Turn your lighting load on. Volts should be much less than 0.5. Most likely you will not be able to detect any voltage.
If you must replace the lugs, duplicate lugs are fine. Cleaning the contact surfaces including frame around screw and the screw itself are mandatory. However, crimp type loop connecters are the best you can get for automotive, RV, and Marine use. I paint over the connectors after proper installation. You can get a small can of marine insulating paint with brush built into the cap. It is in the marine or automotive electrical section of your hardware store. It is designed for this application.
Proper crimping with a pliers type crimping tool is best. I bought the hammer type. It works poorly and inconsistently. I had to put it in a large bench vise to reliably get a proper crimp.
Solder is a poor conductor and should not be used for high current applications. Many people do it and swear by it, but tests show it is not nearly as good as a tight crimp. Star washers are not recommended except in special applications. They will increase resistance. Clean dry tight connections are best.
This might be a good case for taking it to a proper automotive, marine, or RV shop where proper tools and fittings will be available.

[RustyDave]

Excellent. I’ll run this test before I start replacing the lugs. What sort of voltage should I be looking for if it’s a ground connection problem from the lug pictured above?

[Persistent]

Originally Posted by RustyDave

Excellent. I’ll run this test before I start replacing the lugs. What sort of voltage should I be looking for if it’s a ground connection problem from the lug pictured above?

The voltage from the wire to the frame should be 0 volts when your lighting load is turned on. The same should be true measuring across every connection.

In this case you are looking for a problem that is causing a 1 volt line loss. We have been measuring from the positive side to negative side. Again we were looking for 1 volt or more loss. So, 13 volts at the battery dropping to 12 volts at the point being tested.

An alternative is to measure across the connection joint or from one end to the other of a wire. In this case you should see 0 volts. 0.1 or a little more is undesirable, but you are still looking for 1 volt.

[RustyDave]

Got some crimping tools from my buddy. Time to go check the voltage losses and hopefully repair some weak ground connections.

[RustyDave]

I’m seeing a .04-.05 voltage reading when I do the circuit breaker test. I’m seeing a 0 to 0.01 voltage reading when I do the ground test off the back of the trailer by the panel.

[hillbilly3]

Have you tested the switches that you were having issues with yet? Same test as breaker.

[RustyDave]

Originally Posted by hillbilly3

Have you tested the switches that you were having issues with yet? Same test as breaker.

I checked the switch on both ends. It’s showing about .05-.06v with the lights on. Replaced the switch. Showing the same.

[RustyDave]

Ok.
So I’ve replaced the c/b by the batt. Replaced the positive wire from batt to junction box. Replaced the ground that feeds the common bus. Replaced the light switch.

My voltages read under load of the lights today. Batt 12.6, panel 12.2 (better) but switch 11.1. When I turn the lights off everything reads the same.

Need further guidance before I drive this off into a ditch.

On a side note with the furnace going I’m seeing the same 12.6 batt 12.2 panel.

[burglary]

95% of all RV electric problems are the ground problems. Start cleaning all your connections , if any are really bad, use your meter to be sure the voltage is on the right leg. If you get a. Minus sign on the voltage, switch the wires.

[danking49]

I'd go back to the beginning and measure the parasitic current at the battery. It's significant enough in today's RVs that almost all have a battery disconnect switch now. When not in use, turn the switch off or disconnect one side of the battery.

[RustyDave]

Ok. So I have good power at the panel now with the lights on. That voltage drop is in range for the gauge of wire.
Where I’m lost now is at the switch. With the power off it reads normal but as soon as I throw the switch voltage drops from 12.8 to 11.1 at the switch. Both sides. Voltage on both sides of the fuse is normal.

[RichRVat71]

I been doing some research in going solar. I found that the charging votage is important and 13.6 may be low for a full charge. Call the manufacture of the batteries and ask what the charging voltage for their should be.

Originally Posted by RustyDave

Good day everyone.
New to this forum but I'm on my 3rd travel trailer. I'm having some electrical issues and would love to solve this myself prior to calling someone out to deal with it at $150 an hour.
Last camping season we started to get the low voltage warning on the CO detector. Long story short, I took it to the rv place and they said everything was fine and that my batteries weren't charged enough. Charged them for a week and got the alarm again at 4 am dry camping on the second night. I have a 2000 generator and would keep it going for 4 hours daily and I'm very conservative with my power usage. I then purchased new 6v volt batteries and a new Safety Alert unit and the problem continued. Frustrated, I disconnected the CO alarm and bought a battery operated one from home depot (although it doesn't have the propane alarm). I've been using it that way this season but figure it's time to deal with this problem.
Now please excuse me if I don't describe this properly. I've been using this forum to try to trouble shoot but I need some further guidance.
I've plugged the trailer into shore power and I'm getting 13.5 volts at the batteries. They're generally sitting around 13v at this point so the charging unit is working. Also, when I put a load on the batteries, the voltage returns to a previous level after 30 minutes of rest. I've crossed off the batteries and the charging unit off as potential problems.
My overhead lights in the main part of the trailer have 4 sets of fixtures that hold 2 bulbs each (non LED). The odd time when I put the switch on for these they don't turn on for about 5 seconds. That problem is intermittent. I figure this might be the low voltage problem area so I've been focusing on that.
Today, I hooked up the voltmeter to run some test at that light switch. Voltage at the light switch on the battery side was 13.3 but as soon as I turned the switch on it dropped to 12.2 (2 of the 4 light fixtures were selected for this test, 2 bulbs each). I figure that's a significant drop and not even using all 4 fixtures. I decided to test each of the four fixtures separately and each time I turned them on I got a drop from about 13v to 12.46 on all four fixtures individually. Also the voltage seemed to be dropping about .01 every 10-15 seconds. Just out of curiosity I tested the voltage and turned on the bedroom light (separate switch from the other 4 fixtures but same kind of fixture) and it read 12.8 at the same testing location. So basically I'm seeing about a .45v drop for the same kind of fixture on the problem switch area.
So I'm getting good voltage coming to the light switch but when I turn it on with 1-4 of the fixtures attached to the switch I'm seeing big drops compared to the other fixtures in the unit.
I guess I'm looking for guidance from here. I will be switching to LED but I'd like to figure out why I'm getting this low voltage alarm first.
I have a 2011 KZ Spree 281BHS. We love the unit but this problem is driving me nuts.

[RustyDave]

Originally Posted by RustyDave

Ok. So I have good power at the panel now with the lights on. That voltage drop is in range for the gauge of wire.
Where I’m lost now is at the switch. With the power off it reads normal but as soon as I throw the switch voltage drops from 12.8 to 11.1 at the switch. Both sides. Voltage on both sides of the fuse is normal.

I just tested a different switch on the same circuit and getting the same results.

[Persistent]

Apparently you have wide spread corrosion of electrical components. Small improvements from multiple wires, connections, and devices tend to support this conclusion.

I have detailed two methods of measuring voltage drop. Use them on all possible connections and devices. The alternative not including dumping it into a ditch is to hire an RV electrical mechanic to do the search and replace for you. Independent RV repair shops generally do excellent work. Franchised mega RV dealers generally don't do as well.

PS,
You need to fully charge your batteries again. Storing at 12.6 is starting to get a little low for long battery life.