12v lights come on with Inverter

[AndyIndra]

Hi, I have a system where the controller charger my 2 x 12-volt batteries wired together to give me 1 x 24 Volt battery bank. I take 24v off to the buzz bars + & - from there I take off 2 +, 1 to a 24-volt fuse and 1 to the 24-volt inverter and the same for the -
The 24 volts is then put through a voltage dropper to 12v this then goes to a 12v fuse box. All the ceiling fans and lights in my home are 12volt.
THE ISSUE
why when the inverter is on, do the 12-volt lights glow when the lights are switched off. but if I switch off the inverter all is good.
With inverter on and the lights are glowing if I switch the light on, they work fine
I feel something is feeding fed back.

Can anyone Help
Andy

 

[robbob2112]

Ai enhanced first statement

Hi, I have a solar power system where my charge controller charges two 12-volt batteries connected together to make a 24-volt battery bank. I use this 24-volt power to supply both a 24-volt inverter and a voltage converter that drops the voltage down to 12 volts. The 12-volt power is then sent to a fuse box that powers my 12-volt ceiling fans and lights.

The Issue: When the inverter is on, my 12-volt lights glow slightly even when they're supposed to be off. But when I turn the inverter off, everything works fine, and the lights stay off as they should. If I turn the lights on while the inverter is running, they work normally.

It seems like there's some kind of feedback causing this issue. Can anyone help?

Thanks, Andy

My answer
Chances are the inverter is feeding AC power back to the battery string and that is being fed through your buck converter. If they are nearby it could be coupling with the magnetic field.

 

[AndyIndra]

Hi
Thanks the reply
Ok so we know why but what is the fix.
We both know it's feed back
Can you help me fix it

Andy

 

[ConnerLabs]

I kind of agree with ChatGPT that the inverter is feeding an AC voltage back onto the DC wiring by capacitive coupling.

If your inverter has a ground stud on its case, try connecting this to battery negative. If there's no ground stud you can try connecting the green wire (earth/ground/whatever it's called in your country) of the AC output to the battery negative.

For safety, when running a whole house off an inverter like this, ideally the battery negative, AC green wire ground, and AC neutral should all be connected together and all connected to a ground rod or buried metal water pipe, to give a ground reference to the system.

(Edit: for safety also check the AC wiring and appliances in your house that the inverter supplies, for leakage to earth. If you connect the inverter's neutral and ground together, you can use GFCI, or RCDs or whatever your regional name for the earth leakage trip device is.)

 

[TM48]

Be careful grounding the negative battery terminal. Some inverters really don't like it. You better check with the manufacturer.

 

[robbob2112]

My inverter specifically states to NOT connect the battery negative to the AC ground or it will be damaged. It also says not to connect the N to G or it will be damaged. So to prevent damage must read the manual to verify what can and can't be done.

note the answer above was my answer verse the AI - I just had trouble understanding what you wrote so I fed it into the AI and asked for plain english version.

Well, if the coupling is magnetic from the invert to the buck converter just moving them farther from each other should limit the interaction. i.e. if the buck converter is attached to the battery screws at the inverter an laying on top of the inverter lengthen the wires and put them a few feet apart.

A picture of equipment would be useful at this point. Along with a wiring diagram even if it is on paper and you take a picture.

If the problem is because of noise/AC voltage backfeeding the buck converter there are a few ways to fix it... but the simplest check for now is to use your multimeter and check for AC voltage on the DC lines. If there is AC on the battery wires it can be harmful to the battery BMS .

 

[Bop]

Its actually quite a common issue with LED lights (which I am assuming these are) and happens with AC mains (120 and 230v versions) as well as DC ones like mine running directly off the 12vdc battery bank in the shed)

In fact the LED bulbs in my shed do it lol- I actually like it- they use no detectable power from the battery bank (I checked lol, less than my multimeter can measure!!!), yet light up enough to show where the light switches are- each bulb has its switch on the pole directly under it...

It's called 'ghosting'- and its because LEDs are just too damn efficient lol- they can light dimly on microamps of current, and the fix is either fitting better quality LEDs, or fitting a 1megaohm resister across the LED...

 

[ConnerLabs]

Yes, I disagree with ChatGPT on this point, I believe the coupling that allows the "ghosting" current to flow is capacitive, not inductive/magnetic.

Also, my inverter manual never said anything about connecting battery negative, AC ground or neutral. I did it and nothing bad happened. As others have said, you should check the manual for warnings before doing this.

 

[Bop]

I suspect it can be either/or inductive or capacitive- or even a mixture of both...

My 12-85v LED bulbs do it on a DC supply, but some of the cheap AC mains ones did it as well (running on AC)
(tried to get a pic of it, but the phones camera simply doesn't pick up the glow, even though it is actually quite visible to the naked eye...)

It's not the buck converter in his setup, because mine are literally connected straight to the battery bank, and still do it...

 

[efficientPV]

I suspect it is not wired the way you think it is.

 

[sunsurfer]

why when the inverter is on, do the 12-volt lights glow when the lights are switched off.

I feel something is feeding fed back.

It is an interesting problem. Can't be back feed if the switch is open. UNLESS......you have an LED controller that is hardwired all the time and the switch is outside of the power loop. Then it could be noise on the DC side that is getting in through the power wires to the LED controller vs some other method from the air.

 

[Bop]

It is an interesting problem. Can't be back feed if the switch is open. UNLESS......you have an LED controller that is hardwired all the time and the switch is outside of the power loop. Then it could be noise on the DC side that is getting in through the power wires to the LED controller vs some other method from the air.

Like I mentioned before- its a common problem, and will happen with literally one LED bulb with an open mechanical switch in the supply cable...

Each of mine are literally a common feed along the top beam of the shed, with the negative battery lead connected to a lamp base holder, the positive is in a (240v mains rated TPE) dropper down to the (mains rated) switch, the return goes back up the dropper to the lamp base to provide the switched positive 12v from the feed cable- in my case each individual bulb has its own switch and is fed from the common 12v feed (connected direct to the 12v battery bank) and I get it on the LED bulbs here in the shed....

The ones I use here are these, running off 12vdc (the shed uses the one on the right for its lights)


Despite appearances, the shed lights ARE 12v here (using the bulb on the right above) with 12 of them in use around the shed walls... and they all do it...


Effectively each LED bulb is this at its pole- and they still glow too...

No drivers, no buck converter in my case, running straight from the battery bank- and yet...

 

[Recovering EE]

Do you have high-voltage transmission lines overhead nearby?

 

[sunsurfer]

No drivers, no buck converter in my case, running straight from the battery bank- and yet...

Years ago when I worked in communications, It was not totally uncommon to have florescent lights in the buildings at tower sites to glow pretty good from all the RF in the air.

 

[ConnerLabs]

And what do we have in our systems that switches high voltages and currents at high frequency, has lots of long antenna wires connected to it and was probably never EMC tested, I wonder

 

[sunsurfer]

And what do we have in our systems that switches high voltages and currents at high frequency, has lots of long antenna wires connected to it and was probably never EMC tested, I wonder

I think a few here are waiting to see a pic of the inverter. Doubt there is much filtering on the driver side of those cheap HF inverters.

 

[ConnerLabs]

I think a few here are waiting to see a pic of the inverter. Doubt there is much filtering on the driver side of those cheap HF inverters.

This is why I suggested connecting the inverter’s AC ground to its battery negative, as it’s the easiest (but not risk free, check the manual!) way to squish common mode noise coming out of the thing. I honestly think it is transmitting enough RF back into the battery side of the system to light the LED lamps.

 

[Recovering EE]

Years ago when I worked in communications, It was not totally uncommon to have florescent lights in the buildings at tower sites to glow pretty good from all the RF in the air.

Back in the day, when I was a digital communication system R&D engineer, we'd lightning test our designs.

Drove office-mates nearby nuts, because it would make their ceiling fluorescents flash.

 

[Bop]

Years ago when I worked in communications, It was not totally uncommon to have florescent lights in the buildings at tower sites to glow pretty good from all the RF in the air.

Not much RF around me (unless I'm on the radio myself)

Thats from the road out the front, I'm sitting at that arrow right now...
(my driveway is over 500m long, and the nearest neighbour is over a kilometre away)

There bugga all cellphone reception (one spot if I stand on the back of the tilttray, I get 1 bar), a town of 1500 ten km away- then an hours drive to the next one... so I seriously doubt that RF is the issue here lol
(unless it me transmiting- but I'd notice that lol)

One of the reasons I like my place- RF quiet on the shortwave bands...

 

[Bop]

Do you have high-voltage transmission lines overhead nearby?

LOL- the nearest streetlines are over half a kilometre away, the nearest HV lines are tens of km away...

 

[ConnerLabs]

One of the reasons I like my place- RF quiet on the shortwave bands...

Do you turn all your MPPTs and inverters off when you’re on HF then?

 

[Bop]

Do you turn all your MPPTs and inverters off when you’re on HF then?

Don't need to, there is so little interference, it barely registers....
(I get a couple of frequencies you can hear them in operation, but they aren't near where I usually operate, so no reall issue)
If it was an RF problem, I doubt I would even bother turning the rig on lol

 

[AndyIndra]

Hi
Thanks the reply
Ok so we know why but what is the fix.
We both know it's feed back
Can you help me fix it

Andy

Hi All thanks for your help I have looked at a few things but with no luck..but I have found out by removing the drop down 24v-12v I had a bad trip fuse so removed it for now I found that I have AC on all my lines. I used a neon driver that lights up and checked all cables with the inverter on it and it lights up. the batteries terminals light up and I get a small shock from the buzz bar
I have added some pics
Starting 2 fuses for panels from there to controller out of controller to Batteries 24v (12v x2) from batteries to buzz bar then to inverter 240v out of inverter. I do live on an island, but we are 240v 50Hz UK system here (13amp Plugs).
Thank you for helping

 

[ConnerLabs]

As mentioned in this thread, it sounds like you need to properly earth both AC and DC sides of your inverter. The battery negative terminal, inverter’s metal case, and earth pin of the inverter’s output socket, all need to be connected together to earth. You mentioned a “power company outlet” so maybe you can use the earth they provide, or drive an earth rod yourself.

Others have warned that the inverter might be damaged by connecting battery negative to earth. So ideally you should check the manual. However, you’ve proved that there’s dangerous AC voltage on the DC wiring, and I think the risk of electric shock to yourself from that outweighs any possible risk of damaging the inverter by what I would consider to be just earthing it properly.

 

[AndyIndra]

As mentioned in this thread, it sounds like you need to properly earth both AC and DC sides of your inverter. The battery negative terminal, inverter’s metal case, and earth pin of the inverter’s output socket, all need to be connected together to earth. You mentioned a “power company outlet” so maybe you can use the earth they provide, or drive an earth rod yourself.

Others have warned that the inverter might be damaged by connecting battery negative to earth. So ideally you should check the manual. However, you’ve proved that there’s dangerous AC voltage on the DC wiring, and I think the risk of electric shock to yourself from that outweighs any possible risk of damaging the inverter by what I would consider to be just earthing it properly.

I did connect the battery negative to the power company socket but no change. I will try both sides of the inverter and let you know. If I use a test plug in the lounge. that the room run by solar it tells me NO EARTH. I will drop a earth rod outside and connect an earth to this socket circuit. later thanks.