Leaky Inverter





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Thread: Leaky Inverter

  1. #1
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    Default Leaky Inverter

    Hi All, I have a bit of an electrical problem and I was hoping for some advice.

    I recently added a second battery in the boot of my Land Cruiser 76. I've run 16mm2 +ve and -ve wires from the starter battery to a cheap 1500W pure sine inverter under the passenger seat (via a fuze/isolator). From the inverter I've run cables to the boot where I have installed an 80Ah Exide Enduro AGM battery (again fused near the battery). I tested it over a week in Kgalagadi recently and it works like a charm (I was concerned the second battery would not charge well so far from the modern alternator that only seems to put out around 13.6V, but it seems to charge okay: ~12V to 13V in 2 hours of slow driving).

    So here's the problem - the other day during load shedding I was using the inverter in the car to power a few things in my house and I happened to be lying under the car and when I touched the chassis and felt current running through my body. Nothing major, just a tingle. I measured the voltage between the car chassis and the house's earth to be around 40V AC, and I could get around 20V AC just touching my multimeter to the garage floor and the chassis. I don't have a tool to measure AC current.

    The inverter does not have an earth connection, just 12V +ve and -ve with 220V AC 3-prong output. I just checked and there doesn't seem to be continuity between the 12V -ve input and the 220V AC output earth.

    I've read quite a lot online and there seems to be a lot of conflicting information. Some people recommend hammering in earth stakes at every campsite, but that's not really an option.

    So, finally, to my questions: is this a problem? Is this dangerous? Anyone else experienced this? Who in Hermanus/Somerset West/Cape Town would you recommend to have a look at this for me?

    Thanks!

  2. #2
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    Default Re: Leaky Inverter

    I have come across the leakage current coming from the electronics in the inverter. When testes there was not much current as the voltage goes away the moment a discharge path is connected to the inverter. You ought to find a screw on the casing to connect a earth wire and problem solved.
    Normally below 40V you are in no danger unless you catch a freight and injure yourself by reacting to the shock.

  3. #3
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    Default Re: Leaky Inverter

    Quote Originally Posted by ekkekan View Post
    I have come across the leakage current coming from the electronics in the inverter. When testes there was not much current as the voltage goes away the moment a discharge path is connected to the inverter. You ought to find a screw on the casing to connect a earth wire and problem solved.
    Normally below 40V you are in no danger unless you catch a freight and injure yourself by reacting to the shock.
    Thanks Ekkekan. There is no earth screw on the casing. I did do a quick test to see if connecting the casing to the chassis had an effect but it did not seem to make a difference (there was still voltage between the garage floor and the chassis). I will try test again more carefully. Testing is a bit tricky because it seems to take a bit of time for the voltage to build up and I need to load the inverter to get it to happen.

  4. #4
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    Default Re: Leaky Inverter

    drill a small hole and use a self-tapping screw and an earth cable with crimped eyelet ?
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    Default Re: Leaky Inverter

    Quote Originally Posted by jelo View Post
    drill a small hole and use a self-tapping screw and an earth cable with crimped eyelet ?
    Just take proper care when drilling small hole
    The drill can potentially drop metal shaving inside the inverter
    So make 100% sure that none of those drops inside the unit since it can cause serious problems

    Show pic of inverter
    Many of them have external screws mounted
    You can generally turn one of those out
    Take peace of sanding paper and remove the paint on the inside where the screw attaches
    And then fit earthing point with the screw you removed `
    Last edited by Veneficus; 2019/04/16 at 09:37 AM.
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  6. #6
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    Default Re: Leaky Inverter

    Quote Originally Posted by Veneficus View Post

    Show pic of inverter
    Many of them have external screws mounted
    You can generally turn one of those out
    Take peace of sanding paper and remove the paint on the inside where the screw attaches
    And then fit earthing point with the screw you removed `
    correct



    4 options there already.........
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    Default Re: Leaky Inverter



    Eight NOPE 10 NOPE FOURTEEN options on this one...........
    Last edited by jelo; 2019/04/16 at 10:35 AM.
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  8. #8
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    Default Re: Leaky Inverter

    I could earth it to the chassis from one of the screws on the body of the inverter. I just didn't because I assumed if it was meant to be earthed there'd be a dedicated screw for that.

    I just did a quick test. After about 5 minutes of running the inverter with a load I measured 18V AC between the car chassis and garage floor. I then connected the inverter case to the chassis and it made only a slight (~1V) difference. Strange thing I noticed is that the voltage remains after turning the inverter off.

  9. #9
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    Default Re: Leaky Inverter

    The next question would be to give a name and model and one can try and get pictures to see what it looks like. Very strange that the 18V does not go away as you strap the boby of inverter to car chassis.

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    Default Re: Leaky Inverter

    Quote Originally Posted by ekkekan View Post
    The next question would be to give a name and model and one can try and get pictures to see what it looks like. Very strange that the 18V does not go away as you strap the boby of inverter to car chassis.
    I agree. Seems very strange to me. A capacitor holding some charge makes sense, but then it would be DC surely?

    It's a Changi CJ 3000Q - https://m.banggood.com/3000W-12V24V4...l?rmmds=search

  11. #11
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    Default Re: Leaky Inverter

    As the inverter has a 220V input the earth of the supply lead should already earth the box. Make sure that the earth pin of the supply lead is connected to the casing. Further also make sure that the supply lead is in fact earthed from the plug point side. If the plug point is not earthed the inverter cannot be earthed.

  12. #12
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    Default Re: Leaky Inverter

    I don't think it has 220V input. Only 12V in, 220 out.

  13. #13
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    Default Re: Leaky Inverter

    Quote Originally Posted by bobhof View Post
    I don't think it has 220V input. Only 12V in, 220 out.
    Sorry my mistake. I must have looked at a different inverter which had a 220V input and 220V inverter output.

    Still strange if the 220V output earth point is earthed to the frame and to the grid earth that you get the 18V AC.
    Last edited by ekkekan; 2019/04/19 at 04:55 PM.

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    Default Re: Leaky Inverter

    With any transformator or caps etc in a unit generates static electricity it is normal but in some cases it could go up to 140-230 volts when there is or some leakage of electricity or with the insulation of the unit.and this can cause serius problem & injuries !
    As the law states for electrical equipment it is eazy to understand All metal parts must be Earthed
    This include all steel aulm copper carbon so if your inverter or plug extention box etc are covered with any type of metal it needs to be earthed if there is no earthing point then simply dril a hole in a safe place on the metal casing & earth it with a copper insolated wire to the car chasis & or house wiring, many years ago we had kampd at a bush camp & my wife got elect shock when she tried to conect the plug for the caravan , & also when she tried to open the caravan door,after i inspect i found all the armour wires that was used as earthing in the power boxes in the camp site was corroded this end up with no earth and when i messured with a tester between the box lid & soil ground there was almost 230volts we could not do any thing to it but did instead conect a insulated wire on my caravan chasis & earth conection to a tent peg & just hamer it in as you would do with the rest of your tent pens & this sorted it out for a safe camping weekend after this i always had the earth conected to the varavan stabelizer jacks & when i lower the caravan jack it aslo pressed in to the soil making good contact

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  16. #15
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    Default Re: Leaky Inverter

    Quote Originally Posted by ekkekan View Post
    Sorry my mistake. I must have looked at a different inverter which had a 220V input and 220V inverter output.

    Still strange if the 220V output earth point is earthed to the frame and to the grid earth that you get the 18V AC.
    As you say ekkekan it os strange thatbafyer it os earthed there should be no leakage to earth & or the casing then that unit os fualty & should not be used try take it back for refund or replacement

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  18. #16
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    Default Re: Leaky Inverter

    Holy cow.
    Cheers

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  19. #17
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    Default Re: Leaky Inverter

    Thanks everyone. Yeah, I think I'll try return the unit. Not sure if it's a faulty unit or a design flaw. Also not sure if it's dangerous or not, but I'd rather not take a chance.

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