Weird-ass electric behavior

[Captain Goddammit]

I changed out all my incandescent "rope light' to LED rope light, about 200 feet of it. There is a 13-watt red and a 13 watt green fluorescent light. Plugged into "shore power" it all works perfectly, but on the inverter, a cheap square-wave, it now acts weird; the fluorescent lights don't go off when I turn off the switch, and the LEDs get dimmer when I turn off the switch for the fluorescents.
I suppose a double-pole switch that kills the hot and neutral ought to get the fluorescents to go off... but WTF.
Do I just need to pony up for a real sine wave inverter?

[FIGJAM]

What happens if you just turn off the inverter?

Sounds like it might be a short keeping the circuit partialy complete so that it's not shutting off.

[ygmir]

yeah I'd think some sort of short/feeback......also, do you have and wire coil type set ups that might be gleaning power?

eta: I sort of remember a bad ground or ground with resistance, allowing fluorescents to stay on and act weird.

[Sham]

Can you find 12V fluorescent lights? I had some in a work truck and they worked great and used very little power.

[Captain Goddammit]

Everything shuts off if I turn the inverter off, of course. And it all works perfectly on the "shore power" extension cord coming from the house. It just does the weird shit on the inverter.
I know where a good real sine wave inverter for a great deal is, but it's 24 volt input. I could series my batteries, but then I don't know how I'd charge off my 12 volt alternator.

I tried replacing the fluorescent lights with LEDs, no difference. They won't turn off, and unless I have their switch on, the while LED rope lights don't reach full brightness. And again, only on the inverter, not on shore power from the house.
They have separate switches, common neutrals and switched hots. Maybe double-pole switches are the answer, switching the hots and neutrals off?

[Canoe]

Any chance you have a scope handy and can check the waveform shape & peak voltage under the various conditions?

Any difference from running on batteries alone vs. engine & alternator on?

As a test, can you easily hook up and drive each load individually on the inverter directly, as in, bypass the switches, etc.., to see if you get the same when your switches & wring are in play?

[some seeing eye]

Sounds like you had rope lights and changed them, then added the fluorescents. You have a switch panel for the lights that you can plug into the inverter or plug into the shore power. Maybe post a drawing of any before and after and how you change the connection between the shore power and inverter. Are there any possible common grounds or neutral between the AC and DC side? Does the inverter connect either DC terminal to the AC ground or neutral? Frustrating.

[ygmir]

Sounds like you had rope lights and changed them, then added the fluorescents. You have a switch panel for the lights that you can plug into the inverter or plug into the shore power. Maybe post a drawing of any before and after and how you change the connection between the shore power and inverter. Are there any possible common grounds or neutral between the AC and DC side? Does the inverter connect either DC terminal to the AC ground or neutral? Frustrating.

hhhmmmm..........are both grounded to frame? and could there be a battery feed back? at low voltages, maybe a feedback from a battery is enough to excite the lights, even when off? Alternator leakage?
Maybe isolate grounds from eachother?

[Captain Goddammit]

I already had fluorescent lights, but I changed out the incandescent rope light for LED rope light.
There's no ground because there's no frame, the boat hull is the chassis and it doesn't conduct.
The fluorescents used to work, in '08 last time it was on the playa, I just had to turn them on one at a time. (There are five blue-tinted 4-foot 32-watt fluorescent tubes underneath, and a red and a green CFL on each side).
Now they don't work... I can't even get a single incandescent regular light bulb to glow properly - I'm starting to assume my inverters are junk. It all works great on "shore power".
I'll have to go back to my old system, a Honda EU1000 on the swim-step, unless I can scratch up a better inverter.

[Tiahaar]

Heya Capt. I'm thinking both you (with the double pole switch solution) and all the rest that mentioned ground problems are on to the fix. You know how finicky RV's are with their floating neutrals, and how neutrals and line loads are really two sides of the same AC circuit, so if the inverter is floating (and maybe with internal neutral/load reversal) and the downstream stuff is grounded it would be easy for something to get half a wave form for power through a neutral-to-ground path, without blowing a fuse as 'shorted'.

Came across a good read on RV electrics to include for anyone curious: floating neutral

Years ago I worked with a mobile crew living out of RVs and trailers plugged into half baked campground electrics and on many of the rigs you did not want to grab the doorknob with a bare hand especially if the ground was wet...you'd get a good shock.

[Captain Goddammit]

I went through everything, found two issues, apparently I worked too late and had a couple circuits reversed (hot/neutral) and I have a double single-pole switch - two separate switches in one housing, each a single-pole - that I noticed had a little jumper tab that connected both "load" sides of the switches together. WTF. I snapped out the little tab... I had a 120VAC light circuit on one of the switches, and the + side of a 12VDC light circuit on the other. Maybe I cooked something in the inverter before finding that little dammit-tab.

That did solve the side-lamps that wouldn't turn off though.

I unplugged everything from the inverter (1200 watt continuous), and it only halfway lights up a 60-watt incandescent light bulb.

Edit... OK I get it, they tabbed both switches together so you could run one "hot" into it and control two different circuits... well fuck, I needed two entirely separate switches... at least they provided the little breakaway tab to separate them, I just didn't notice it. Probably did cook something.

[ygmir]

sounds like you found a big part of it. good luck. Hope your inverter is ok

[Elliot]

Came across a good read on RV electrics to include for anyone curious: floating neutral

Excellent!

[Token]

Everything shuts off if I turn the inverter off, of course. And it all works perfectly on the "shore power" extension cord coming from the house. It just does the weird shit on the inverter.
I know where a good real sine wave inverter for a great deal is, but it's 24 volt input. I could series my batteries, but then I don't know how I'd charge off my 12 volt alternator.

I tried replacing the fluorescent lights with LEDs, no difference. They won't turn off, and unless I have their switch on, the while LED rope lights don't reach full brightness. And again, only on the inverter, not on shore power from the house.
They have separate switches, common neutrals and switched hots. Maybe double-pole switches are the answer, switching the hots and neutrals off?

The big diesels run 24V alternators. A trip to the right junk yard might be a good deal.

So many benefits to doubling the voltage.

[Captain Goddammit]

I work with big diesels, I'm a crane truck operator... I never see trucks with 24V systems. All I ever see is 12V.
I use GM CS-130 alternators because they are cheap in junkyards and make a lot of current at idle speed.
Also, I run both my alternators in parallel when running at night with all the lights on for max charging. They need to be the same.
I'm about go out and see if I just popped some fuses, but I sorta don't care, I decided to order a true sine wave inverter so the LEDs don't flicker, the fluorescents don't behave weird, I get better efficiency, and I can use it on my "real" boat too. Screw the square wave shitbox. It's never really been "right" anyway.

[Elliot]

I concur. I started driving 18-wheelers in 1982, and they were 12 Volts already then.