Can I safely connect my Inverter to my EHU input socket?

[timbo99]

Although I have a twin Gaslow system I’m looking to utilise my Solar/Lithium system to greater effect e.g. Induction Hob and/or the inbuilt Truma Water Heater, Fridge etc.
My Rig & Kit
Burstner Delfin
2kw Renogy Inverter with mains switchover facility. Earthed to chassis.
The Inverter outlets connect to 240v sockets via RCDs and are independent circuits from the original mains sockets that run from the EHU input.
240v weatherproof external outlet socket from the inverter fitted.
300ah FOGSTAR Drift Lithium battery.
Solar panels totalling 380w
30amp B2B.

Seemingly I am now able to run a standard EHU cable from the external outlet that’s powered from the Inverter to the 3-pin original Burstner EHU Input which in turn has an RCD Consumer Box panel. All the EHU electrics remain unchanged from the original Burstner Delfin installation as my additional electrics from Solar Panels and Inverter go direct to the Fogstar Leisure Battery and do not go via any Burstner circuits.

Because I’m using the original mains EHU input I’m “fooling” the system to think it’s on a mains site hook up and therefore powers up the Truma water heater and the fridge too!

On the face of it I have enough wattage/Amp-hours to run up to a 2kw induction hob and alternately run the Truma HW heater. I have the Fogstar Battery Management App which tells me what is occurring and herein is my question. The Truma HW Heater should be drawing 3.9 A on the 900 W or 7.8 A on the 1800 W settings. According to my Fogstar App it’s drawing between 70-80 Amps!! Not for very long as I shut it down very promptly.

Am I doing something dangerously wrong and potentially frying my circuits and killing my battery or is the App giving me a false reading? None of the other meter readouts are indicating anything other than a normal draw.

Some helpful guidance from electrically minded Funsters please.

 

[timbo99]

When you are in your house and you plug in a 1000w heater the amps you draw are 1000/230 = 4.34. (watts/volts=amps) but when you use it via your inverter you are drawing 1000/12=83 amps. Your 300a lithium battery will power a 1000w load for approximately 2.7 hours before you kill it. I get your idea about "fooling" the system but be careful here if the site hookup and the 12v side ever meet there will be a vey loud bang !!. Just use the built in inverter sockets. Put a plug on one end of some 2.5 cable and attach the other end to a wall socket. Your other option is a rotary switch where you connect your ECH input and your inverter input then you simply turn the switch to which one you are using but they can never accidentally get joined together.

 

[meanders]

Put a plug on one end of some 2.5 cable

A widowmakers in effect then? Exposed live pins. Even out of an inverter 230v can kill especially anyone with a weak heart or a child. In the event of an unlikely but very possible unexpected death, I would hate to be the one explaining to a coroner and then the police that I did it because someone on the web said it was OK.

 

[Tombola]

When you are in your house and you plug in a 1000w heater the amps you draw are 1000/230 = 4.34. (watts/volts=amps) but when you use it via your inverter you are drawing 1000/12=83 amps. Your 300a lithium battery will power a 1000w load for approximately 2.7 hours before you kill it. I get your idea about "fooling" the system but be careful here if the site hookup and the 12v side ever meet there will be a vey loud bang !!. Just use the built in inverter sockets. Put a plug on one end of some 2.5 cable and attach the other end to a wall socket. Your other option is a rotary switch where you connect your ECH input and your inverter input then you simply turn the switch to which one you are using but they can never accidentally get joined together.

You may have misunderstood pal.
He is taking the cable from the output of his inverter and plugging it in the ehu socket on the outside of his van with a commando socket.

Thus not possible to mix ehu and inverter power. In effect making his van the self ehu.

 

[LithiumConvert]

Having read many of your posts, I'm supprised that you don't comprehend the theory of the storage bank acting as a "sump".

Oh. I do understand it. But, I tend to forget that some motorhome owners have the payload capacity to carrry a huge inverter and a matching solar farm on the roof.

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[headlight]

I've followed this thread and although what the OP suggests will work I can't see the point.
Electric hot water and heating are to power hungry to run off a battery and inverter.
Far better to run these on gas.
Also by 'fooling' the van into thinking it's on EHU then the battery/inverter will be powering the onboard mains battery charger to replace the current being taken by the battery with power from the battery, so the mains charger would need to be disabled/disconnected.
I can't see the point ?

 

[meanders]

You may have misunderstood pal.
He is taking the cable from the output of his inverter and plugging it in the ehu socket on the outside of his van with a commando socket.

Thus not possible to mix ehu and inverter power. In effect making his van the self ehu.

Probably. I had followed the earlier putting it back into the EHU input, but this suggestion was none specific and I have previously seen someone do similar feeding back into a 13A socket from a generator! I had a duty to flag up the risks.

 

[motorhome andy]

I've done a simpler system
I've made a lead with a 3 pin plug on each end and plug one into the inverter and the other end into a 240v existing socket and just liven up the 240v system so not affecting any other system in the motorhome

 

[LithiumConvert]

I've done a simpler system
I've made a lead with a 3 pin plug on each end and plug one into the inverter and the other end into a 240v existing socket and just liven up the 240v system so not affecting any other system in the motorhome

I would give you a "Funny" reaction, but some funsters might fhink you are serious.

 

[meanders]

I've done a simpler system
I've made a lead with a 3 pin plug on each end and plug one into the inverter and the other end into a 240v existing socket and just liven up the 240v system so not affecting any other system in the motorhome

I am unsure if that's a deliberate wind up or genuine suggestion given the previous few posts. Either way, please do not encourage people to do this. When the plug is out but connected to the inverter it is live and a killing machine. Plugging it into the EHU inlet means mains cannot be inadvertently connected, and no-one gets hurt with floating live pins.

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[Divertrev]

So accepting Meanders explanation for the apparent high amperage draw it all seems to be working without issue, induction hob, fridge and heater etc. and no worrying electric burning smells!

Thank you everyone for their input. Just to clarify a few points. The Renogy Inverter has two sockets to which I plug in RCD plugs to my cabling to independent wall sockets. All the plugs (Inverter, RCD and appliances) have max 10amp fuses to protect against an unforced overload. The Inverter and Mains socket circuits have no means of being inadvertently or indeed deliberately connected! The Renogy Inverter has a mains switchover facility but that is not used and is reduntant. I could connect it in if I was hooked up to a proper campsite supply.

The remaining issue is whether the circular charging aspect is a problem. I'm not familiar with other MH electrics but my 2006 Burstner has an E-Box (Transformer/Rectifier/Charger) which looks to be a complex (expensive if I fried it) box of tricks and although it seemingly has options to "tap-in" additional kit to its circuitry by a person who really understands the Burstner electrics, I haven't, and is the reason all my additions are quite separate to the original circuitry. The problem is there is no apparent means of turning off the charging function. I've tried pulling a fuse labeled 'Internal Charger' but that doesn't appear to have any effect. Has anyone a view on whether this non-virtuous charging circle is damaging? I get that the Inverter is taking a draw (0.5A) in its own right and all the time there is a bit of sun the PV panels will be putting something positive into the equation so with 300 amphours of Lithium battery I'm not seeing a high battery drain as a problem. The advantages would outweigh that. If plugging in the inverter to the EHU is going to cause a problem then I won't. I didn't fit the external socket in order to connect into the EHU socket, I saw that as just an added bonus. Clearly the charger is not going to put more in than is being drawn, it's not the next best to perpetual motion! But am I going to do damage?

 

[autorouter]

I am unsure if that's a deliberate wind up or genuine suggestion given the previous few posts. Either way, please do not encourage people to do this. When the plug is out but connected to the inverter it is live and a killing machine. Plugging it into the EHU inlet means mains cannot be inadvertently connected, and no-one gets hurt with floating live pins.

I think it's just not explained very well. All the MH sockets could be wired to a single 13A plug, to act like a glorified mains extension. Then you can plug it into a single socket that runs from EHU, so all the sockets run from EHU. Or you can unplug it from the single EHU socket and plug it into the inverter. No floating live pins anywhere.

 

[meanders]

That would work within the limitations of a single 13A plug. However if the boiler and fridge both run and you then put something else on, even when on EHU with a full 16A available (Meaning you can draw perhaps 18 to 20A without dropping the trip) so you could be drawing that through a 13A plug which is a substantial overload. Much better to have correctly wired change over.

 

[stevewagner]

For me fitting the Renogy inverter and connecting direct to the CU was far simpler than most suggestions I’ve seen. I switched off the mains charger, run fridge on gas when parked and everything works as it should and is safe.

 

[motorhome andy]

Autorouter yes and its only for the air frier
The fridge and boiler are on gas

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[Tombola]

Probably. I had followed the earlier putting it back into the EHU input, but this suggestion was none specific and I have previously seen someone do similar feeding back into a 13A socket from a generator! I had a duty to flag up the risks.

I was quoting timbo99 mate.
But yes I agree with your suicidal point

 

[headlight]

So accepting Meanders explanation for the apparent high amperage draw it all seems to be working without issue, induction hob, fridge and heater etc. and no worrying electric burning smells!

Thank you everyone for their input. Just to clarify a few points. The Renogy Inverter has two sockets to which I plug in RCD plugs to my cabling to independent wall sockets. All the plugs (Inverter, RCD and appliances) have max 10amp fuses to protect against an unforced overload. The Inverter and Mains socket circuits have no means of being inadvertently or indeed deliberately connected! The Renogy Inverter has a mains switchover facility but that is not used and is reduntant. I could connect it in if I was hooked up to a proper campsite supply.

The remaining issue is whether the circular charging aspect is a problem. I'm not familiar with other MH electrics but my 2006 Burstner has an E-Box (Transformer/Rectifier/Charger) which looks to be a complex (expensive if I fried it) box of tricks and although it seemingly has options to "tap-in" additional kit to its circuitry by a person who really understands the Burstner electrics, I haven't, and is the reason all my additions are quite separate to the original circuitry. The problem is there is no apparent means of turning off the charging function. I've tried pulling a fuse labeled 'Internal Charger' but that doesn't appear to have any effect. Has anyone a view on whether this non-virtuous charging circle is damaging? I get that the Inverter is taking a draw (0.5A) in its own right and all the time there is a bit of sun the PV panels will be putting something positive into the equation so with 300 amphours of Lithium battery I'm not seeing a high battery drain as a problem. The advantages would outweigh that. If plugging in the inverter to the EHU is going to cause a problem then I won't. I didn't fit the external socket in order to connect into the EHU socket, I saw that as just an added bonus. Clearly the charger is not going to put more in than is being drawn, it's not the next best to perpetual motion! But am I going to do damage?

Maybe I am missing something here but I still can't see the advantage of doing this ?
You have refillable lpg so cheap heating, hot water and fridge running.
Plus in my experience hot water and heating run better on gas than electric as on gas they reach temperature quicker.
I have 230AH of LifePo4 and a 2,000 watt inverter.
I run my fridge, heating and hot water on gas.
The inverter has 2 outlets so I have each one supplying a double socket with 2 USB outlets.
They are totally separate to my vans 240v system.

 

[Divertrev]

Maybe I am missing something here but I still can't see the advantage of doing this ?
You have refillable lpg so cheap heating, hot water and fridge running.
Plus in my experience hot water and heating run better on gas than electric as on gas they reach temperature quicker.
I have 230AH of LifePo4 and a 2,000 watt inverter.
I run my fridge, heating and hot water on gas.
The inverter has 2 outlets so I have each one supplying a double socket with 2 USB outlets.
They are totally separate to my vans 240v system.

No 'headlight' you're not missing something because I didn't add in another bit of info.! We are off to the Outer Hebrides for three weeks and apart from one LPG filling station in the north there is no where else to top up my Gaslow cylinders. So as I have the external weatherproof socket from the inverter I thought it would be a neat idea to connect to the EHU socket if I thought gas was going to be a real problem. Your system is pretty much mine although I have a couple of more sockets and have the RCDs too. I think the system is electrically safe, unless someone suggests otherwise. My issue is now that because I would be coming in via the EHU the 'E-Box of tricks' kicks in the charger and I have no means to independantly switch that off. My question therefor is:-
Will I be damaging anything by connecting up the way I have described?

 

[timbo99]

A widowmakers in effect then? Exposed live pins. Even out of an inverter 230v can kill especially anyone with a weak heart or a child. In the event of an unlikely but very possible unexpected death, I would hate to be the one explaining to a coroner and then the police that I did it because someone on the web said it was OK.

you missed the rest where I said "and attach it to a wall socket". Should have gone to specsavers ! I don't think you should be messing about with electricity . . .

 

[autorouter]

Clearly the charger is not going to put more in than is being drawn, it's not the next best to perpetual motion! But am I going to do damage?

No I don't think any damage would be caused. However I've not actually tried it. The charger will presumably be putting its full output into the battery, as it would whenever the battery is supplying a heavy load. So it would be pushing out say 20A, and using probably 25A to generate that output. So it would be draining the battery overall by say 5A. Not a massive problem, just a total waste. But nothing will be damaged.

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[headlight]

No 'headlight' you're not missing something because I didn't add in another bit of info.! We are off to the Outer Hebrides for three weeks and apart from one LPG filling station in the north there is no where else to top up my Gaslow cylinders. So as I have the external weatherproof socket from the inverter I thought it would be a neat idea to connect to the EHU socket if I thought gas was going to be a real problem. Your system is pretty much mine although I have a couple of more sockets and have the RCDs too. I think the system is electrically safe, unless someone suggests otherwise. My issue is now that because I would be coming in via the EHU the 'E-Box of tricks' kicks in the charger and I have no means to independantly switch that off. My question therefor is:-
Will I be damaging anything by connecting up the way I have described?

I don't think you'll damage anything I just think it is very inefficient and a lot of hassle.
How big are your Gaslow cylinders ?

 

[meanders]

you missed the rest where I said "and attach it to a wall socket". Should have gone to specsavers ! I don't think you should be messing about with electricity . . .

Oh dear. Near 50 years experience, a HNC in Electronics and Electrical Engineering, and a science and technology degree all wasted then.

 

[Divertrev]

So do you have something like a contactor in circuit or hat detects as soon as mains power is detected,?, or is it a fancy inverter with the live mains controller built in? Not seen any with that, but it doesn't mean they don't exist. It basically the same as.UPS.

Yes, the Renogy has the switchover facility and is therefore a built in UPS. Explained and demonstrated on the Youtube.

 

[meanders]

I will take your word for it rather than watch a video.

 

[Divertrev]

I don't think you'll damage anything I just think it is very inefficient and a lot of hassle.
How big are your Gaslow cylinders ?

11 & 6Kg. Yes agree not an efficient use of energy but an 'in case of need' option as I have the external socket and cable/connection on board in any case. Going next week, potentially not the sunniest for the panels, and may need to have the heater running more than usual.

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[autorouter]

My issue is now that because I would be coming in via the EHU the 'E-Box of tricks' kicks in the charger and I have no means to independantly switch that off.

That doesn't sound right. Which make/model of E-box is it? I'm sure there should be a way to do that.

 

[Divertrev]

I will take your word for it rather than watch a video.

Thanks for your input 'Meanders'. My take on the responses is my 'plug in' mayy not be the most efficient use of stored battery power but if needs be it would work and not do damage with the charger operating within the circuit.

 

[headlight]

11 & 6Kg. Yes agree not an efficient use of energy but an 'in case of need' option as I have the external socket and cable/connection on board in any case. Going next week, potentially not the sunniest for the panels, and may need to have the heater running more than usual.

I don't know your gas usage but I could easily go 3 weeks running my fridge, cooker, heating and hot water off my 2 x 6kg bottles this time of year.

 

[Divertrev]

That doesn't sound right. Which make/model of E-box is it? I'm sure there should be a way to do that.

Not sure of the actual model but it's c2006. I've had the MH for 12 years and although never had a need to switch the charging function off, I can't find such a switch and studied the Instruction Book and there's no reference to such an option. I can switch the whole unit off but then I have no services and I believe if it's on a Hook-Up it will still charge up the batteries.

 

[Divertrev]

I don't know your gas usage but I could easily go 3 weeks running my fridge, cooker, heating and hot water off my 2 x 6kg bottles this time of year.

I suspect you are correct and I will have plenty of gas for my purpose but as I say, I have the cable etc and it would be an option. Just didn't want to damage anything.

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