Renogy, Lithium and Inverter pass through

[Insider]

Hi
I currently have a Forte PVC with 180Ahr LA, a 60A Sterling B2B and 180Watt solar with a Victron 75/15. I have not used EHU in 3 years but as part of the Sargent system there is a Sargent PX300 in place. I have a small 300W inverter installed and have a purchased but not installed renogy 2000W inverter.

Now that Forgstart Drift have appointed an Irish supplier I am looking to move to Lithium and as part of that install also put in the renogy to let me get the use out of various items. The pass through(UPS) function of the renogy intrigues me and I am hoping to have all the sockets in my van at 240V while off grid so I guess my question is. Can I cut my EHU cable inside the van before it goes anywhere, connect it into the 240V input of the renogy and take the output of the renogy and connect that back to the cut EHU cable. As part of this I would disconnect the PX300 battery charger and fit a Victron battery charger between the EHU and the renogy. I have taken the diagram of the 240V electrical system and put my kit in to demostrate what I hoping to achieve.

I am doing this to be able to use the sockets in the van for microwave, induction hob etc. I am not looking to power the Truma heating element or run the 3 way fridge off 240V.

The greenbox is the proposed Victron 20A charger
The bluebox is the proposed renogy 2000W inverter
The red X is the proposed removal of the PX300 charger

TIA

 

[Tombola]

Even easier..pretty much plug and play if you make it just for sockets.....see the video below..this was one of the first about the renogy ups inverter, that i used, but there are many vids now

 

[stevewagner]

Hi
I currently have a Forte PVC with 180Ahr LA, a 60A Sterling B2B and 180Watt solar with a Victron 75/15. I have not used EHU in 3 years but as part of the Sargent system there is a Sargent PX300 in place. I have a small 300W inverter installed and have a purchased but not installed renogy 2000W inverter.

Now that Forgstart Drift have appointed an Irish supplier I am looking to move to Lithium and as part of that install also put in the renogy to let me get the use out of various items. The pass through(UPS) function of the renogy intrigues me and I am hoping to have all the sockets in my van at 240V while off grid so I guess my question is. Can I cut my EHU cable inside the van before it goes anywhere, connect it into the 240V input of the renogy and take the output of the renogy and connect that back to the cut EHU cable. As part of this I would disconnect the PX300 battery charger and fit a Victron battery charger between the EHU and the renogy. I have taken the diagram of the 240V electrical system and put my kit in to demostrate what I hoping to achieve.

I am doing this to be able to use the sockets in the van for microwave, induction hob etc. I am not looking to power the Truma heating element or run the 3 way fridge off 240V.

The greenbox is the proposed Victron 20A charger
The bluebox is the proposed renogy 2000W inverter
The red X is the proposed removal of the PX300 charger

TIA

View attachment 974025

That’s virtually what i did except I haven’t changed the charger, just switched it off. With solar and B2B I don’t need a charger

 

[Sleeveless]

Check the input wattage ( consumption) of your induction hob and microwave , with 180Ah battery and 2000w inverter you're probably sailing close to the wind, especially with the hob, also cable sizes are also a factor .

 

[fred_jb]

You need to be aware of the need to avoid having a mains battery charger being connected to the inverter. If you do you could end up in a downwards spiral in terms of battery charge! This can happen due to the inverter taking 12V power from the leisure battery, converting it to 240V, and the battery charger then using that 240V to convert to 12V to charge the very same battery that the energy came from in the first place. With the conversion inefficiencies in both inverter and battery charger you would have a net loss of charge in the battery which will be bigger the longer that situation persists.

In any case, the inverter should not be connected directly to the EHU socket as that will bypass any protection such as the master RCD in your mains distribution panel - assuming you have one. I believe the manual says that the inverter should be connected on the non EHU side of the master RCD so that it is protected. It is also not ideal to have all mains consumers routed via the inverter, especially if you have or plan to install at some point items which exceed the 2000W capability of the inverter, such as mains powered aircon.

If you have a mains distribution panel with both a master RCD and separate RCD for each mains circuit, then you should identify which RCD is protecting the 240V sockets and put the inverter inline between the output of the master RCD and the input of the one supplying the sockets.

^{_{Subscribers  do not see these advertisements}}

 

[fred_jb]

I've had a closer look at your circuit diagram and see that you are disconnecting the existing charger, so no risk of it being powered by the inverter, and you propose connecting a new charger directly to the EHU input which avoids that issue.

However, I don't see how you will avoid the Truma or fridge taking 240V from the inverter when not on EHU, unless you switch the invertor off when not on EHU which seems to defeat the object of having it! Maybe you can turn off mains to these manually while using the inverter but surely not ideal to have to remember to do this. Far better to arrange for the inverter to only supply the mains sockets in the first place.

I also don't think connecting the new mains charger this way is a good idea, for the same reason that you shouldn't connect the inverter directly to the EHU input either, namely that neither would have the benefit of the van's master RCD tripping if the incoming supply developed a fault.

 

[Mike001]

I have done what the OP is asking.
Ran 2x new cable from the incoming EHU to cupboard where there is: Lithium, invertor and charger.
Installed an outlet RCD protected socket in the cupboard. This runs the charger only when plugged in to mains, plus invertor pass-through.
From the invertor output it goes back to the EHU to join to the cable that feeds into the main RCD etc distribution unit.
Works very well. Incoming mains is protected via the socket RCD and the charger can only ever be "ON" when plugged in to mains.

 

[fred_jb]

I have done what the OP is asking.
Ran 2x new cable from the incoming EHU to cupboard where there is: Lithium, invertor and charger.
Installed an outlet RCD protected socket in the cupboard. This runs the charger only when plugged in to mains, plus invertor pass-through.
From the invertor output it goes back to the EHU to join to the cable that feeds into the main RCD etc distribution unit.
Works very well. Incoming mains is protected via the socket RCD and the charger can only ever be "ON" when plugged in to mains.

That solves the protection issue assuming both charger and inverter are both fed from an RCD protected socket and not directly from the EHU, though I am not sure what you mean by saying the "inverter output goes back to the EHU to join to the cable that feeds into the main RCD". This would suggest that the output of the inverter when in pass through mode is connected to a raw unprotected EHU feed - effectively putting an unprotected path in parallel to a protected path so the inverter is still exposed to any derangement of the external mains supply via its output. To avoid this you would need to connect the output of the inverter to the non-EHU side of the RCD instead.

Maybe you have no connection directly from the EHU to the distribution box RCD in which case it would seem to be redundant.

In any case this way of installing an inverter still means that everything using mains, not just sockets, is being supplied via the inverter, either from an EHU, or if no EHU is present, autoswitched to the inverter's 240V generated from the 12V supply. This may not be an issue in your case but the OP has a Truma heater with electric element and a 240V capable fridge, and probably wouldn't want these running off the inverter, so would have to take steps to avoid this.

 

[stevewagner]

Seems to be a lot of over engineering going on here. Mine works extremely well. Charger turned off fridge on gas and Truma on gas.

 

[fred_jb]

Seems to be a lot of over engineering going on here. Mine works extremely well. Charger turned off fridge on gas and Truma on gas.

Not over engineering - just doing it right for maximum convenience of use!

I don't have to turn anything off while on the inverter because it only supplies my mains sockets.

^{_{Subscribers  do not see these advertisements}}

 

[stevewagner]

Not over engineering - just doing it right for maximum convenience of use!

I don't have to turn anything off while on the inverter because it only supplies my mains sockets.

My charger is off permanently and the fridge is more efficient on gas, as is the heating. So as I said over engineered in my opinion.

 

[fred_jb]

Well, over engineered implies something over complicated and not needed. I would disagree with that. To do this properly is no more complicated than other solutions being proposed, and in some cases simpler with no extra RCD or wiring.

Furthermore this requires no manual intervention to ensure the inverter is not overloaded with unsuitable loads.

For example 3 way fridges may default to 240V unless manually switched to gas or 12V. You also need to make sure that AC options for heaters and water heaters are turned off, and that you don't turn on aircon if fitted.

All I had to do was as follows:

Connect input of inverter to output of master RCD.

Disconnect input of secondary RCD/breaker serving sockets from master RCD output.

Connect output of inverter to input of RCD/breaker serving sockets.

Job done!

Of course some very basic electrical installations may not have a separate RCD/breaker for different mains circuits, but even then splitting off the socket wiring should not be difficult.

 

[mick qc]

Disconnect input of secondary RCD/breaker serving sockets from master RCD output.

I take it you mean the other mcb.
As most consumer units for campervan have two MCB’s you use one to feed the sockets via the inverter and the other mcb for anything else.

 

[fred_jb]

Disconnect input of secondary RCD/breaker serving sockets from master RCD output.

I take it you mean the other mcb.
As most consumer units for campervan have two MCB’s you use one to feed the sockets via the inverter and the other mcb for anything else.

Well my van has something like a mini domestic fuseboard. It originally had the master RCD plus three other breakers, one of which connected to the sockets so it was fairly easy to get the inverter connected, just fiddly getting at the wiring, but you only have to do it once.

If most motorhomes only have two circuit breakers, then as long as one of them is dedicated to the mains sockets then yes I guess that is the one to connect the output of the inverter to.

Does your system also have a master RCD providing the supply to the two MCBs? If so the output of that would be where to connect the input of the inverter.

This is what mine looks like now. I wanted a master circuit breaker as it is not recommended to routinely use an RCD as a master circuit breaker so I added a second box and put the master breaker and master RCD in that. This then left me a spare slot in the original box to feed the aircon which I installed.

 

[mick qc]

I have one of these.

Pardon our interruption...

At the moment one of the MCB goes to a socket for my mains charger and my truma boiler the other MCB feeds my 2000 Renogy inverter.
My inverter then goes directly ( from the output plug connection on the back of the inverter) to a socket for a microwave and then on to another socket for when I use my air fryer obviously I only use one appliance at a time.

The input to my RCB is from my hook up connection, nothing else.

I have always meant to have some form of circuit breaker via the the inverter to the sockets but I thought it wasn’t as important considering I only use one appliance at a time.
so I basically just rely on the appliance itself and the fuse in the three pin plug.
Everything is adequately eartged including the inverter unit itself all on separate connection to the chassis

^{_{Subscribers  do not see these advertisements}}

 

[Insider]

Check the input wattage ( consumption) of your induction hob and microwave , with 180Ah battery and 2000w inverter you're probably sailing close to the wind, especially with the hob, also cable sizes are also a factor .

Putting in 300Ahr Lithium within 50cm of the invertor. Would not be connecting 2000W inverter up to 180Ahr LA!!

 

[Insider]

OK - thanks for the replies. I guess I should have clarified a few things that have come up in the comments. I mainly use 12V around the van but want to be able to run microwave, induction hob, small kettle the odd time and be electric bike ready but never ever ever all at once!! I would also never use the fridge or truma on 240V while on battery - the fridge is manual changeover. In fact most of the time the inverter will be turned off and I won't be on EHU so there'll be no 240V at all in the van. I eat my porridge cold - I like it that way....but my wife likes it microwaved and as luck would have it there's a microwave in the van that has been unused for the past 5 years.

I could just take the output of the inverter and present it to a self installed socket but then anytime I'd want to use the inverter I'd have cables going across the floor. Idealy I'd feed the inverter output to the input of the RCD for the socket circuit but they are at opposites end of the van and I'd have to run two cables which would take a considerable amount ot time and effort. In my mind it's much easier to break the EHU cable which is close(1.5m) to where the inverter and battery will be. As below the EHU cable is going into the van input connector(master RCD). I intend adding the bit circled in red - breaking the EHU cable, feed it into an RCD, feed that into the input of the inverter, take the output of the inverter and join that back to the other side of the cut EHU cable which in turn goes into the original input connector.

I guess my questions were is my plan stupid because I forgot something major and it seems to be OK with caveats on what is being used etc but I was already OK with that. Next what safety precautions do I need to take and the wishdom here is install an RCD just inside where the EHU is coming in. Adding in the Victron battery charger near the lithium rather than using the existing PX300 which is far away from the battery and using the Sargent circuitry is also a nice bonus.

Thanks to all

 

[Sleeveless]

Putting in 300Ahr Lithium within 50cm of the invertor. Would not be connecting 2000W inverter up to 180Ahr LA!!

Ahhh, apologies , but didn't see 300Ah lithium mentioned in original post , I have the Renogy 2000w inverter with 2X 105 Ah lithium , it's OK with consumers up to approx 1400W but no more for any period exceeding a couple of minutes , 300Ah should do it though.

 

[Insider]

Looking at kit to do the install would the following do as my RCD. Seems cleaner than installing a mini board

Screwfix

 

[fred_jb]

Without a link to the Web page for this device it is difficult to comment on the spec. Personally I would prefer a standard 2 pole RCD as this thing seems to be intended to protect a single spur rather than multiple circuits.

If space is an issue you can get small housings to hold single 2 slot devices. I have used one of these for the switch to disconnect my solar panels - to the left of the main board in the following picture.

^{_{Subscribers  do not see these advertisements}}

 

[fred_jb]

Sorry - just spotted the link in your post! Still can't tell for sure, but looks like single pole switching rather than two pole. For a main RCD I would think 2 pole switching is better.

Edit: checked the further info and it confirms single pole, so not ideal.

 

[Rob Hammond]

Well, over engineered implies something over complicated and not needed. I would disagree with that. To do this properly is no more complicated than other solutions being proposed, and in some cases simpler with no extra RCD or wiring.

Furthermore this requires no manual intervention to ensure the inverter is not overloaded with unsuitable loads.

For example 3 way fridges may default to 240V unless manually switched to gas or 12V. You also need to make sure that AC options for heaters and water heaters are turned off, and that you don't turn on aircon if fitted.

All I had to do was as follows:

Connect input of inverter to output of master RCD.

Disconnect input of secondary RCD/breaker serving sockets from master RCD output.

Connect output of inverter to input of RCD/breaker serving sockets.

Job done!

Of course some very basic electrical installations may not have a separate RCD/breaker for different mains circuits, but even then splitting off the socket wiring should not be difficult.

Gone over my head

 

[Insider]

Sorry - just spotted the link in your post! Still can't tell for sure, but looks like single pole switching rather than two pole. For a main RCD I would think 2 pole switching is better.

Edit: checked the further info and it confirms single pole, so not ideal.

Fred,

you're right - Going to go for this instead and install a small cabinet of the type you have your solar MCB in. 16A will be more than enough.

Thanks

Amazon Link