Rewiring to use the inverter

[Googlebot]

In a similar theme to my other threads, I will be posting this as I go along.

In the Hymer Exsis the whole electrical system is protected by an RCD which feeds a 10amp MCB. That’s it, everything in there is on the same circuit. No big deal but if the supply gives 16 amps, you can’t use more than 10 without the MCB tripping which is annoying.

It has also been annoying me only having one mains socket at the inverter but other than unplugging the battery charger and manually changing the fridge over, the one circuit meant I couldn’t connect it direct. To rectify this, I have decided to change the consumer unit and wire in a changeover switch.

After reading lots of threads, I managed to find a DIN rail mounted changeover for the inverter and hook up that goes inside the consumer unit. As I need to change the consumer unit regardless, it seemed a neat solution and to change over, I just flick the switch and turn off the fridge and charger circuits as the same time.

I need to run new cables for the charger and fridge and swap the consumer unit out. Then run a cable to the inverter, a job for tomorrow now but everything is ready.

 

[autorouter]

Those single-pole MCBs are not suitable for a mobile installation. You should be using double-pole MCBs, or at least single pole plus neutral MCBs. Since these are sometimes not easy to source, an alternative is to use several (2-pole) RCBOs instead.

 

[Googlebot]

Ah, that’s not good news. Time for a rethink.

 

[Raul]

RCBO’s at toolstation for about 20 quid each. You will also need to bond AC neutral to chassis on the inverter if you haven’t already. It’s a spade connector inside. Then run earth to inverter chassis.

 

[Googlebot]

I have found some dual pole MCB’s locally. Do the Toolstation RCBO’s go down to 10 amps?

Loads of single pole RCBO’s around.

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[sallylillian]

Those single-pole MCBs are not suitable for a mobile installation. You should be using double-pole MCBs, or at least single pole plus neutral MCBs. Since these are sometimes not easy to source, an alternative is to use several (2-pole) RCBOs instead.

I get the double pole MCB's from Europe. Does anyone have a UK stockist, I was only lucky one time! Now with import hassles it works out expensive.

 

[Raul]

I have found some dual pole MCB’s locally. Do the Toolstation RCBO’s go down to 10 amps?

Loads of single pole RCBO’s around.

You can get 6,10,16 and 20 amp. Compare screwfix and toolstation for price. Some are cheaper, some more expensive. I got a 6 and a 10 amp. I have no use of 16a in the van.

 

[eddie]

It would be simpler and better to simply connect the 13 amp sockets to the output of the inverter with a 220vac auto changeover relay

When on mains everything works

No mains? simply turn inverter on and only 13 amp sockets work

No messing around having to remember turning fridges and chargers on and off

 

[Googlebot]

You can get 6,10,16 and 20 amp. Compare screwfix and toolstation for price. Some are cheaper, some more expensive. I got a 6 and a 10 amp. I have no use of 16a in the van.

So the single pole RCBO’s are suitable? I couldn’t find anything I could make sense of. Some on the IEE forums said they were and others that they weren’t?

 

[Googlebot]

It would be simpler and better to simply connect the 13 amp sockets to the output of the inverter with a 220vac auto changeover relay

When on mains everything works

No mains? simply turn inverter on and only 13 amp sockets work

No messing around having to remember turning fridges and chargers on and off

Thanks Eddie, I was going to do this but the option to switch the charger and fridge off independently regardless of power source was my rationale. With the lithium I wanted the option to turn off the charger and still use everything else when freezing.

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[sallylillian]

Did get some in the UK but took some time due to stock.
Pole plus neutral

 

[Lenny HB]

Thanks Eddie, I was going to do this but the option to switch the charger and fridge off independently regardless of power source was my rationale. With the lithium I wanted the option to turn off the charger and still use everything else when freezing.

Very easy to rewire a Hymer mains as the mains circuits are all plugged together using Wago Winsta Midi connectors. I fitted a 30 amp change over relay and rejigged the mains so that the fridge & charger are only connected when on EHU.

 

[John H.]

It would be simpler and better to simply connect the 13 amp sockets to the output of the inverter with a 220vac auto changeover relay

If you already have the inverter (without prioriity switch), then you ccan buy just a priority switch.

Alternatively, you can just plug the EHU into the inverter if you only need it occaisionally.

 

[Googlebot]

If you already have the inverter (without prioriity switch), then you ccan buy just a priority switch.

Alternatively, you can just plug the EHU into the inverter if you only need it occaisionally.

I have the changeover switch.

Just need to separate the circuits with the correct MCB’s.

 

[sallylillian]

Very easy to rewire a Hymer mains as the mains circuits are all plugged together using Wago Winsta Midi connectors. I fitted a 30 amp change over relay and rejigged the mains so that the fridge & charger are only connected when on EHU.

Or fit a Victron Multi (3000 watt up) and get 2 AC outs, one switched one not and run the fridge and other EHU only consumers from the unswitched AC out. You get the best of both worlds UPS on all consumers when on EHU and managed inverted consumers. I dumped the Buttner inverter charger on day 2 of Morelo ownership and rejigged the distribution boxes to accommodate this option.

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[John H.]

I am interested. How are you going to route a separate cable from the consumer unit to the charger on your Exsis.

 

[Googlebot]

Or fit a Victron Multi (3000 watt up) and get 2 AC outs, one switched one not and run the fridge and other EHU only consumers from the unswitched AC out. You get the best of both worlds UPS on all consumers when on EHU and managed inverted consumers. I dumped the Buttner inverter charger on day 2 of Morelo ownership and rejigged the distribution boxes to accommodate this option.

If I had the budget, this would be my option.

I am interested. How are you going to route a separate cable from the consumer unit to the charger on your Exsis.

Either, under the double floor to heater box then under shower tray and across the back or under the seats then across entrance door under fridge and to back.

Will let you know once I do it.

 

[eddie]

Thanks Eddie, I was going to do this but the option to switch the charger and fridge off independently regardless of power source was my rationale. With the lithium I wanted the option to turn off the charger and still use everything else when freezing.

Why would you want to turn off the charger?

When your hooked up its on, and when you have no hook up? It’s off!

It will end in tears when you end up forgetting to turn your fridge back on, and also MCB are resettable fuses, not designed as an on/off switch

 

[Googlebot]

Why would you want to turn off the charger?

When your hooked up its on, and when you have no hook up? It’s off!

It will end in tears when you end up forgetting to turn your fridge back on, and also MCB are resettable fuses, not designed as an on/off switch

If it’s freezing I can’t charge the lithium and the inbuilt charger doesn’t have a temperature sensor. I wanted the option to turn the heating on via the mains but not the charger.

I could put a switch in or do it as you suggest and use an auto changeover.

Dear lord this is minefield.

 

[Lenny HB]

If it’s freezing I can’t charge the lithium and the inbuilt charger doesn’t have a temperature sensor. I wanted the option to turn the heating on via the mains but not the charger.

Doesn't your BMS take care of that?

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[sallylillian]

Another plus for a Victron Multi, temp sensing.

 

[Googlebot]

Doesn't your BMS take care of that?

It might but I wouldn’t want to rely on it with £1400 at stake.

Another plus for a Victron Multi, temp sensing.

Yes, I agree, if I had the spare cash, it would be in the Motorhome now.

 

[sallylillian]

Based on your concern why not install a heat pad under the battery(s) as you will have EHU its consumption is irrelevant?

 

[Googlebot]

Based on your concern why not install a heat pad under the battery(s) as you will have EHU its consumption is irrelevant?

They are in separate compartments.

I might just go for what eddievanbitz has suggested. If it’s that cold, I have gas!

 

[Googlebot]

Okay, a new consumer unit fused with dual pole MCB’s and an auto changeover on the sockets circuit only.

An RCD in-line for the inverter supply to sockets and earthed with bonded neutral at the inverter.

Have I got that right?

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[Lenny HB]

You could fit a temperature controller in line with the mains to the EBL to stop it from switching on at low temperatures, like the ones we use on the fridge fans.

 

[Raul]

So the single pole RCBO’s are suitable? I couldn’t find anything I could make sense of. Some on the IEE forums said they were and others that they weren’t?

Some are some not. If in doubt, go for double pole mcb.

 

[eddie]

Aww it seems like we’re all having a ‘pop’ but we’re trying to help

When it is zero in the van, where will you be?

if it’s too cold for your Lithiums, you’ll be freezing, as will all of your water supply

If your not using your van, the lithium’s won’t need a charge anyway

And if it’s really cold and your not using the van, it makes sense to leave an oil filled radiator or a greenh heater on anyway

 

[Googlebot]

Aww it seems like we’re all having a ‘pop’ but we’re trying to help

When it is zero in the van, where will you be?

if it’s too cold for your Lithiums, you’ll be freezing, as will all of your water supply

If your not using your van, the lithium’s won’t need a charge anyway

And if it’s really cold and your not using the van, it makes sense to leave an oil filled radiator or a greenh heater on anyway

It’s fine, I would much rather know now than when I install everything!

Just off to return the many items I now don’t need.

Found some local dual pole MCB’s so will grab them today.

If anyone can recommend an auto relay and box to put it in, that would be awesome.

Really appreciate everyone’s help.

 

[Ian Bosman]

Just check the CBE Circuit Breaker Consumer unit, 25 amp RCD with two 13Amp MCB. Not certain whether single pole or two pole.

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