# Instructions how to disable habitation cutoff Sargent EC 325



## skiboycey (May 21, 2009)

I promised a few people I'd send pictures of this once I got a minute.

I originally asked on the forum how you could disable the annoying habitation cutoff on the newer Sargent EC 325 units so that I could run the engine and charge the battery in an emergency without having to sit in the dark or with candles and nobody seemed to really know. You can't just pull out the 'engine running wire' as this will stop the charger working and also mean the step retract etc. won't work.

Not being feint of heart I pulled the unit apart and worked it out for myself. Very easy, in fact, and it looks as though it's been designed to run either with our without the cut off for different markets. With this modification the habitation electrics will all work once the over-ride switch is activated but the water pumps will not (though it wouldn't be hard to get them going either but I don't need that particularly). All the things like step retraction etc still work and battery charging is not affected. In fact nothing is affected at all if it's left switched off and only the internal lights, cooker ignition etc. will work with it switched on. It does mean I can now charge the battery if I'm 'caught short' and still watch the telly and make a brew whilst waiting for a hopefully sunny day the next day so the solar panel can do its job.

Here's some step by step instructions.

STEP 1.

Here's my box with the switch on the outside. You'll need a good quality 25A switch or you could wire the switch to a 40A relay that you place inside the unit if you feel you need more power than 25A.

STEP 2

I added a warning notice on the switch for completeness and to make it look tidy. I'll find my stencil set and do it in the same font as the other writing eventually but this will do for now.

STEP 3

Remove the top cover. You'll need an 'anti-tamper' torx bit with a hole in it, number 15, I think. You can buy them in any hardware store. There are four screws, two top, two bottom. Front cover lifts away but make sure you've pulled the fuses for both engine and leisure batteries and that it's NOT CONNECTED TO THE MAINS! Once you get the cover off you'll see the main board. The conncetions we're interested in are to the left of the big relay marked 'RX1-240' and below the small round white fuse to the right side of the board.

More to follow in a moment as I'm only allowed 3 attachments per post... Give me a minute to post the next two sections so that they stay together before any replies, please...


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## skiboycey (May 21, 2009)

*Disabling habitation cut-off EC 325 part two*

OK...

STEP 4

If you look to the left of the relay marked 'RX1-1240' you'll find the two main feeds to the habitation unit marked 'switched load' and 'cont load' which sort of gives the game away! The 'switched load' has two leads sticking out of it, both brown. These both do the same job so you can pull one out and nothing changes. Pull out the upper lead (it's neater that way but doesn't matter if you choose the lower one) and pull it to one side to be re-attached later.

STEP 5

Identify the 'cont load' that is just above the 'switched load'. You'll need to pull this lead out as well before making up a lead which will split this supply. Put the lead (it's grey with a blue stripe) to one side for now.

STEP 6

Make up a splitter cable to go into the 'cont load'. You'll need to run a spade connector to the cont load then put a male spade onto it. From this male spade you then run another lead with a female spade on that. You plug the grey and blue 'cont load' lead that was originally plugged into the board into the new male spade on your splitter cable and keep the new female 'tail' long enough to run to our switch which we have put on the front panel. The photo shows the new lead in place and the disconnected second 'switched load' brown lead waiting to be moved to the new switch.

Last section to follow....


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## skiboycey (May 21, 2009)

*Disabling EC 325 habitation cutoff part 3*

Right, nearly there...

STEP 7

Below the small white fuse (which is the fuse from the 240v supply to the onboard charger in case it ever stops working and you wonder where it is) the two brown wired habitation wires are attached to a secondary board at positions A17 and A19. You can trace these and discover that they both do the same job. This is why I assume the unit is pre-built to take different wiring layouts for different markets otherwise why put two cables in doing exactly the same job? Anyway this is just for reference and so other techie people can satisfy themselves that the wiring is correct.

STEP 8

This is another view of the splitter cable. You can see that I've now taken the second brown cable and run it towards the switch on the front of the panel.

STEP 9

This shows the new switch. You attach the new splitter cable to one side of it and the second 'switched load' cable to the other. I used the one which runs to A17 on the sub board. This means when the switch is activated the switched and continuous loads are connected together. Dont' worry they are exactly the same load but with a cut off relay on the switched side. A much more elegant solution would have been to put the switch onto the coil of the cut off relay so that you could control if it was working or not but this would require demounting the circuit board and re-soldering etc. This solution achieves exactly the same result but is slightly less elegant but a lot easier to achieve. The photo shows the brown wire still to be attached because it's not quite long enough to go to the over-ride switch with the front off. You push it on as you replace the front...

That's it! Now with the over-ride switch off the whole thing is as standard. With it switched on the habitiation lights, cooker ignition etc. will work if you start the engine. The unit will still say 'System disabled engine started' and the step will retract and the battery will charge. All we've changed is to tap the continuous load supply across to the the switched load for the right hand fuse block and all those circuits running from it.

If you then stop the engine everything will keep working but remember to turn on the main panel again before disengaging the over-ride as othewise everything will go off as you do so. You must also remember to turn it off if you shut down the van as otherwise the habitation circuit will stay live and possibly discharge your battery. It's best to use it solely in an emergency if you need to do an engine battery charge at night if you are wild camping and get 'caught short'. Of course it should never be used whilst driving...

Any questions happily answered. And before anybody says anything 'Yes it is modifying the vehicle' but then so is putting a satellite dish on the roof, putting Gaslow bottles on-boad, adding solar panels or any number of other modifications. These instructions are intended for adults who can understand in what circumstances to use the over-ride and the potential pit-falls of fiddling with wiring or using it whilst the vehicle is in use. If you like your decisions taken for you by bureacrats, the police, governments or unelected quangos then please ignore what's here and carry on sitting in the dark every time you start your engine!

Regards, Mark


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## Richard_the_Rogue (Jun 11, 2009)

I may be talking rubbish here but...

You speak of the two brown wires (switched load) as doing the same thing, and effectively treat one of them as redundant. Your modification means that with the new switch on, all appliances are fed via the one wire (This may also be the case with the switch off, but I don't know enough about the circuit to be sure).

It might be the case that the two wires are there because the total current draw when all appliances are on exceeds the current capacity of a single wire of that gauge. If this is the case, your modification risks placing an overload current on the single wire, with the possibility of the wire overheating, melting, or even causing a fire.

As I say, I'm not familiar with the circuit so can't make any definitive comments, but it might be something you want to look into further.

Cheers,

Richard.


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## skiboycey (May 21, 2009)

>>If this is the case, your modification risks placing an overload current
>>on the single wire, with the possibility of the wire overheating, melting,
>> or even causing a fire. 

Both wires are the same gauge as the one running to the leisure batteries and all the current must flow up that one (much longer) wire to get to the charge unit. Therefore the two cables supplying the habitation are twice as big as the one going to the battery and also much shorter (just as important) so there can be no problem with only using one as this is just a continuation of the main battery supply. The max charge the automatically disconnecting charge/supply unit can achieve is 25A (325W). The whole thing is also fused at 20A from and the max load I can get with everything turned on including the extractor fans and heater blower is only 18A. The wires are 2.5mm square which is rated conservatively at 22 amps for a 2 metre run so there's plenty of redundancy built in.

It would also be possible to replace the two wires with one rated at an equivalent of the original two put together - probably 4 or 5 square mm. I didn't do this as I felt there was sufficient cross sectional area already. I may, however, do this at a later date now I know it works properly and how helpful it is in everday use. My wife recently had our first baby and I stayed in the hospital car park for a week whilst she was in maternity. As the weather was grey the solar panels weren't up to much so I just sat and watched telly with the engine on for an hour each morning to charge the batteries up enough to keep me going.

Don't forget this is a work around just for me to use and would not be put into production nor is it tested for every eventuality. In essence I keep an eye on it and will probably eventually make it a bit more robust. This is the first prototype, if you will...

You're correct to point this out, though, and it's one of the reasons forums are very good as people sometimes see mistakes that weren't apparent to the person originally doing the modification.

Regards, Mark


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## Richard_the_Rogue (Jun 11, 2009)

Hi Mark,

You clearly know what you are doing. Nice mod.


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## autotrailscoutman (Jun 29, 2014)

*EC 500 unit*

Hi Mark.
nice mod but it was totally different to the Sergent EC500 model so when I opened it up I couldn't work out what to do. Any ideas?

Steve


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## dovtrams (Aug 18, 2009)

That is impressive, well to me it is. If I tried it, 1 it would stop working and 2 the MH would probably blow up.

Very clever.

Dave


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## philoaks (Sep 2, 2008)

*Re: EC 500 unit*



> Hi Mark.
> nice mod but it was totally different to the Sergent EC500 model so when I opened it up I couldn't work out what to do. Any ideas?
> 
> Steve


I think you may have a long wait for an answer. The OP was from 2009 and the last time Mark visited this forum was in 2011


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## autotrailscoutman (Jun 29, 2014)

*Habitation lights working again*

Hi again.

I snipped the blue wire on the 6 pin WHITE plug in the EM40 Sargent unit. Everything seemed to work although it prevented me from using the electric step so I put on a separate switch so I can isolate it when needed. Now I can have the habitation lights on when required! I did look in the EC500 Sargent unit but it was difficult to work out what to snip.


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