12V System does not seem to function. NEED HELP!!!

jaymag_87

We need Electrical System HELP!!!

We have a 2017 T@G Max XL. When we are running on shore power there are no problems that I can tell. However when we are trying to run on battery power only, we get nothing. When hooked up to the TV, nothing. I’ve checked all the fuses in the Converter, as well as the fuse at the batteries. They are all good, as far as I can tell. We are running two 6V Golf Cart Batteries, in series. I’m getting 13.01 V on my Multimeter, across both of them. 6.49V across one. 6.51V across the other.
When I pull the fuses and check the voltage across the fuse ports I’m getting the following:
DC Circuit #1 = 0.00 V
DC Circuit #2 = 0.00 V
DC Circuit #3 = 0.00 V
DC Circuit #4 = 11.43 V
Reverse Battery = 0.00 V
Battery Wire Fuse Port = 0.02 V

When on Shore Power I’m getting:
DC Circuit #1 = 10.71 V
DC Circuit #2 = 10.25 V
DC Circuit #3 = 0.99-1.01 V
DC Circuit #4 = 0.61 V
Reverse Battery = 12.80 V
Battery Wire Fuse Port = 0.02 V
When I pull the fuses for DC Circuits #1 and #2, a little red light comes on, but not on #3 and #4. (That’s confusing as well).

I don’t recall any issues last several trips. Those consisted of RVing/Tailgating at Texas A&M Football Games, operating off a Honda eu2000i Inverter/Generator.

The only thing I can think of is this. We have a 12V Defroster Fan that we have previously used for heat. The last time we tried to use it, it kept blowing the 15A fuse on DC Circuit #2. We replaced it with a 30A to see if that would blow. It didn’t. Then a 25A, same result. Next tried a 20A, it blew. It was at this point that we tried running off battery power. That’s when we noticed the problem. Do you think this fuse swapping might have caused the issue? The Converter has a statement that says, “Max Fuse Size 25A for DC CIR1-CIR4”.

Yes, the battery disconnect is in the ON position.

Any ideas? Due to leave on a 9 day trip on 12/21.

I know...tl;dr.

LuckyJ

What you guess I would beleive could be right.

I remember using a higher numer fuse to replace the one from my YJ full pump a long time ago. I was doing this, cause I was far from home and a sunday night, so ran out of the right fuse, decided to put on a higher number fuse, ended up burning the wire from the fuse block all the way to the full pump.

So I would go back to basic, and pull the converter, test the power from the battery to the wire that would bring power to the converter, en from there, check on circuit at a time with one fuse at a time, then work my way with more fuse.

Never pulled the converter so far, but it should be fairly easy to isolate the right output for each fuse. You will have the oportunity to check those splice conector at the same time and see if none have melted.

Good luck

WilliamA

Jaymag,
You shouldn't check for power across a fuse block with a multimeter. Check for voltage on each side of the fuse block between the fuse block contacts and ground. Probe each side of the fuse block with the red probe to ground with the black probe. If you check for voltage by going across the fuse terminals, you are essentially replacing your fuse with the multimeter. It'll not tolerate the potential amperage. First thing to check is the battery to ground connection. Next, check for voltage from the hot battery to ground. Then work your way in with the meter checking from the hot wire to ground where the 12v circuit enters the converter.

WilliamA

LuckyJ

@WilliamA said:
Jaymag,
You shouldn't check for power across a fuse block with a multimeter. Check for voltage on each side of the fuse block between the fuse block contacts and ground. Probe each side of the fuse block with the red probe to ground. If you check for voltage by going across the fuse terminals, you are essentially replacing your fuse with the multimeter. It'll not tolerate the potential amperage. First thing to check is the battery to ground connection. Next, check for voltage from the hot battery to ground. Then work your way in with the meter checking from the hot wire to ground where the 12v circuit enters the converter.

WilliamA

His way of doing it it is way better than mine, since he really start with the basics! I was jumping way pass basic, and explanation was probably making it more complicated!

Luc

jaymag_87

WilliamA and LuckyJ

Thank you for the advice. I learned a lot about my T@G electrical system

I chased wires. I pulled out the converter to get to the wiring harness and found out there is a wiring diagram on the back of the cover that shows the white wire is for the Negative. The red wire is the battery positive. The yellow wire, green wire, and blue wire are positive 13.6 V output for the DC appliances.

I checked all my circuits, several times.

On battery power, I was getting 12.93 V coming in, checking from the Hot Wire to Ground, per WilliamA’s advice. When checking voltage on each side of the fuse block between the fuse block contacts in the ground I was getting virtually zero on every circuit except Circuit 4 (Red). On Circuit 4 (Red) I got 12.93 V. Same as what was coming in. When I disconnected the blue, green, and yellow leads and checked the voltage of the lead coming out of the Converter across to ground, I still got virtually zero.

On shore power, when I checked the voltage on the side of the fuse block between fuse block contacts and ground I was getting 13.65 V at each circuit. When disconnecting the blue, green, and yellow leads and checking the voltage of the lead coming out of the Converter across to ground, I got the same 13.65 V at each circuit.

It didn’t make sense that I was getting full DC output on shore power but not on battery power.

It took me a while to realize that Circuit 4 (the Red Wire Circuit) was not an output circuit like Circuits 1, 2, and 3 (blue, yellow, and green, respectively). You see, Circuit 4 (Red) is apparently, an Input Circuit. I finally looked at the fuse I had pulled and replaced a million times in this deal. It was blown. It is amazing what happens when you replace a blown fuse.

Apparently, when we were testing the offending 12V heater fan, when we swapped out the 15A fuse on Circuit 2 for a larger fuse, it blew the fuse on Circuit 4 (Red). For some reason, our Converter does not have the magic little, red "Hey, I'm Blown" light on Circuits 3 and 4, like it does on Circuits 1, and 2. Also, the fan only blows the fuse when you plug it in. If I remove the fuse, plug in the fan, replace the fuse, and then turn the fan on, it functions fine. I find that a bit odd, but not completely.

Long story short: Check all the fuses before chasing non-existent electrical problems.

WilliamA

As to the "no led on the input" the led would need to be circuited on the battery side of the converter to work properly. The down-circuit leds can be wired with a reverse relay (light on if the relay is off) but to do that for the input wire would be more difficult because of the need to wire the circuitry "before" the converter input and have it switchable between battery and shore power or rectified to prevent problems with the switching between batt/shore power.

As to blowing the fuse when you plug it in, that's a common occurrence called "arc fault". High amperage circuits arc when energized. Switches are designed to handle loading arc, fuses are not. The combination of amperage draw and (probably) heat induced in the fuse from the arcing are more than the fuse can handle. Any switching (either by closing or opening the circuit) causes arcing, which acts as a capacitor of sorts and can momentarily induce up to 10 times battery voltage into the circuit. It's the same principle that burns out both headlights when one blows. Interesting stuff.

It sounds like your defroster is dangerously close to the max amperage the circuit will carry or it wouldnt do that to fuses. Not a bigger fuse, but a smaller wattage defroster may be in order....

WilliamA

jaymag_87

Thanks, WilliamA. I’ve learned quite a bit about the electrical system, though this situation. Looks like we’ll have to find a different way to warm up our T@G.

WilliamA

Jaymag,
Yeah, that's a tough one. The search for DC electric heaters has gone on as long as there have been trailers. Certainly as long as I've been hanging around them. There are many good posts here and on the LG forum about the subject. I penned up a long, (boring) article with calculations and the results of my experiments in T@G heating, but the short version is it takes about 600-800 watts of heat to "efficiently" heat a T@G. At 110V that's about 6 or 7 amps which is easily in the range of many portable electrics. As I said in that article, to get the same work (heat) from 12V would take 66 Amps or so, which isn't really in the feasible category. Plus, it would be inherently dangerous to boot. Most 12V heaters (I used to be an air cooled VW guy) you can get online and in parts stores work out to be about 12 amps of draw and for that you get about 144 watts of heat. Even 12 amps is a lot of power for a single or even dual batteries. Given the high amperage draw and the anemic heat from 144 watts, it's not really worth the investment. For sure, it's better than nothing, but in the end is really hard on the electrical system overall and is potentially the culprit for a lot of problems.

If you're interested, here's a link to an easy volt/amp/wattage calculator that puts things in perspective:

https://www.rapidtables.com/calc/electric/Volt_to_Watt_Calculator.html

It's an eye-opener to run the numbers and see actually how much is necessary for moderate heat.

I've played with my setup in many configurations and have found that for anything close to efficient, you'll need 800 watts of heat. Now if the goal is just to take the chill off on a 50 degree morning, you might be able to use something in the 200 watt range and get by pretty well. But it's pretty close to impossible with known tech to get from 175 watts to 600 watts without either going to 110 A/C or propane. I have done a LOT of looking at different propane units and some are actually pretty close to what I'd want to try if I needed the off-grid heat and didn't want to run a generator (which I have and use) but then I haven't gotten my hands on any of those units to test them and see how they work in the real world. In addition to the usual problems with propane units, they get really finicky really quickly at anything above 4,000 feet of altitude. That's a problem for me as I want to be able to go there too without re-jetting or re-regulating the furnace for altitude. Don't forget either, propane units use a lot of electricity. Certainly not as much as an electric heater, but more than you can comfortably replace without mechanical advantage (Tow vehicle charging or generator). Unless you've got a solar grid system and the weather cooperates, you won't be able to keep up for long running a furnace off 12 volts, no matter how efficient they are.

I'm a big fan of forced-air as opposed to hot water boilers etc and just like that when I turn mine up, it's instantly putting out heat. I don't have to wait for the water to boil, then convect up to the registers and so on. I want to be able to turn it on and just forget about it. For my money, it must be safe, fast and reliable. That takes a bit of work but not as much as you might think. I put a small forced air furnace in my LG Teardrop (600 watts) and added an 800 watt unit to my T@G. Both worked flawlessly and without any issues whatsoever. It can be done. Keep in mind that I want to be able to camp in any weather at most any temperature. With my current setup, 9 degrees F is easy, quiet and fast. I've no doubt it would keep me warm at -20, although I don't really have the desire to find that out.

Play with the wattage calculator and see what your math comes out to. It's all really just math. To heat your trailer at 50 degrees efficiently you need AT LEAST 350 watts of heat. Colder requires more. There aren't any shortcuts or magic answers to that one.

WilliamA

Michigan_Mike

Another alternative would be to use an extension cord for the defroster and don’t plug it into your trailers electrical system, but instead plug it into a spare plug receptacle at the campground pedestal. The only downside to this might be that the pedestal 110V receptacle might have a GFI which might trip because of the load provided by the defroster. In that case and as William notes, look for a smaller heater and something that the trailer circuitry is capable of handling.

Somemedic

@WilliamA said:

That takes a bit of work but not as much as you might think. I put a small forced air furnace in my LG Teardrop (600 watts) and added an 800 watt unit to my T@G. Both worked flawlessly and without any issues whatsoever.

WilliamA

I'd like to know more about your set up or running something in the basement

WilliamA

Somemedic,
PM me on this...
WilliamA