Inverter producing 12V when switched off

[ridgy]

I have a Renogy 2000W inverter installed and connected to the house battery switch and when doing some electrical testing for another reason, I was surprised to find 13V (engine had recently run) at the house battery switch output terminal even though the battery switch was off.

At first I thought it was a switch failure but soon ruled that out. Eventually I deduced that the inverter, connected to house supply, would produce 13V if turned on even if no 240V appliances were used.
Even with both the battery switch and and the inverter turned off there was still 13V on the output side.

This means that turning off the house supply effectively does nothing as there is still 13V at the busbars from the inverter.
I really would have thought that turning the inverter off would kill this supply but no. I will do more testing to see how long it takes this charge to dissipate.

Is this normal? I'm thinking to fit another switch between the inverter and the house supply as it seems wrong to have this residual current floating about.
For me, when the house battery switch is off, there should absolutely be 0V on the output side of the switch.

 

[kwb78]

Inverters can have some quite large capacitors on the DC side. Does the voltage persist after the battery has been disconnected for a long period?

 

[William_H]

Some inverters and even generators are set up to sense if a load is applied and then turn it all on. To sense if a load is applied then something like 12v would be fed to output so that any drain (load switched on) on that 12v would indicate 240v power needed. I wonder if that is what is happening. ie check data on the inverter. Just a thought ol'will

 

[MontyMariner]

As #2. I would isolate then strap a 12v light bulb across the output.

 

[PaulRainbow]

I have a Renogy 2000W inverter installed and connected to the house battery switch and when doing some electrical testing for another reason, I was surprised to find 13V (engine had recently run) at the house battery switch output terminal even though the battery switch was off.

At first I thought it was a switch failure but soon ruled that out. Eventually I deduced that the inverter, connected to house supply, would produce 13V if turned on even if no 240V appliances were used.
Even with both the battery switch and and the inverter turned off there was still 13V on the output side.

This means that turning off the house supply effectively does nothing as there is still 13V at the busbars from the inverter.
I really would have thought that turning the inverter off would kill this supply but no. I will do more testing to see how long it takes this charge to dissipate.

Is this normal? I'm thinking to fit another switch between the inverter and the house supply as it seems wrong to have this residual current floating about.
For me, when the house battery switch is off, there should absolutely be 0V on the output side of the switch.

Doesn't make any sense. The inverter makes 240v from 12v DC, not the other way around. I'd suspect, as others have said, some residual current. Easy way to test for that is turn the batteries off, then turn some loads on, see how long they stay on.

How is the inverter connected ? Surely not straight to the busbars, bypassing the main isolator ? Is the 12v input fused ? Is the inverter Earthed ?

 

[PaulRainbow]

As #2. I would isolate then strap a 12v light bulb across the output.

No need if the main busbar is live, just turn some loads on.