Sargent Ec400 wiring

[Hobbzy]

Hi all, I'm fitting a b2b charger in my MH by bypassing the split charger within the sargent unit, I know I have to fit an isolation relay to stop both chargers trying to charge at the same time. My question is, should the isolation relay be connected to the vehicle battery or the leisure battery side of the system? Or would either work just a well?

P.s there are 2 live cables each for both the vehicle and leisure batteries in P1 and P2 of the sargent unit does it matter which one is used to connect the relay?

 

[CAB96]

Hello and welcome to the forum.

I can't help I'm afraid, but I'm sure someone knowledgeable will be along soon.

 

[JimmE]

I fitted a relay to disconnect the engine battery when the engine is running.

You need to disconnect both cables (they use two thinnner cables rather than one thicker cable), so would need a ‘double pole’ relay (effectively two relays in one) or else you’ll have to use two relays as I did.

I guess technically with a suitable crimp and suitably rated relay, you could also use a single relay for both cables by joining both together on the same terminal. I didn’t consider that at the time!

 

[Insider]

Think I might have a solution here. Need to check my Sargent version in the morning.

 

[Insider]

this is what I used.

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[Hobbzy]

I fitted a relay to disconnect the engine battery when the engine is running.

You need to disconnect both cables (they use two thinnner cables rather than one thicker cable), so would need a ‘double pole’ relay (effectively two relays in one) or else you’ll have to use two relays as I did.

I guess technically with a suitable crimp and suitably rated relay, you could also use a single relay for both cables by joining both together on the same terminal. I didn’t consider that at the time!



View attachment 953374

That's great, thanks JimmE. Instead of using 2 relays couldn't piggyback spade connectors be used to link the 2 thinner cables to the same terminal on the relay? Also do you have any idea of the cable size/amp rating of the thinner cables?

 

[Hobbzy]

View attachment 953376this is what I used.

Thanks insider

 

[Insider]

Thanks insider

You're more than welcome.

I used a three way spade connector from 12V planet to join my two incoming wires into a single connection for the relay.

12V planet spade

 

[Hobbzy]

What size single cable did you use to connect to the relay?

 

[Hobbzy]

You're more than welcome.

I used a three way spade connector from 12V planet to join my two incoming wires into a single connection for the relay.

12V planet spade

What size single cable did you use to connect to the relay?

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[Insider]

What size single cable did you use to connect to the relay?

Apologies re the delay. I think I used 16mm2 cable. This is way too much I know but I always way over spec cabling. Excuse the mess in the picture - in one of my other threads I am replacing some of the floor due to an incorrectly sealed gas locker that let in water from day 1.

 

[Insider]

Apologies re the delay. I think I used 16mm2 cable. This is way too much I know but I always way over spec cabling. Excuse the mess in the picture - in one of my other threads I am replacing some of the floor due to an incorrectly sealed gas locker that let in water from day 1.



View attachment 954656

Woops. Was not 16mm2. Think it was 12mm2 but to be honest on that short a run anything from 6mm2 will do - it's a tiny run

 

[tmc]

View attachment 953376this is what I used.

Hi, Could you explain please as to why the Leisure battery also does not need to be disconnected?
Also just asking just in case you know...when removing a PX300 mains charger it would be handy to use the mains connection from the Sargent unit to the new charger. I cannot find info on what current this output will take. The PX300 is 3amp, my new one will be Votronic Pb 1250 SMT 3B.
Thanks

 

[Insider]

Hi, Could you explain please as to why the Leisure battery also does not need to be disconnected?
Also just asking just in case you know...when removing a PX300 mains charger it would be handy to use the mains connection from the Sargent unit to the new charger. I cannot find info on what current this output will take. The PX300 is 3amp, my new one will be Votronic Pb 1250 SMT 3B.
Thanks

Whole point of adding in a B2B is to give better charging to the leisure battery. When there is an existing split charge relay you need to disconect that when the B2B is active as essentially they would be competing against each other. However you cannot disconnect the split chage relay completely as certain things like the steps and fridge will stop working. Hence the relay in the diagram. However end result is better charging for leisure battery

I have not actually connected to EHU since doing solar and B2B two years ago. My setup works really well but when I go over to Lithium it's likely I'll have to replace the PX300 with something from Victron. I would not be looking at the 240V amperage though - I'd be looking at it from a 12V point of view which is more standard. I think the PX300 is rated at 25Amp.

 

[Simonty]

Hi , I am in the process of doing this conversion , but can I confirm which side of the ec400 needs disconnecting. I have seen another post on another site that disconnects the leisure battery side and this wiring diagram disconnects the vehicle battery from ec400 ? I realise that either will work in principle but when engine running does the ec400 not take power to work heating fridge and low level lighting from vehicle battery when driving ?

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[Insider]

Hi , I am in the process of doing this conversion , but can I confirm which side of the ec400 needs disconnecting. I have seen another post on another site that disconnects the leisure battery side and this wiring diagram disconnects the vehicle battery from ec400 ? I realise that either will work in principle but when engine running does the ec400 not take power to work heating fridge and low level lighting from vehicle battery when driving ?

The relay disconnects the vehicle battery when it senses vehicle powered on in the diagram I supplied. The B2B supplies the power to charge the leisure battery and thus the 12v for the fridge.

 

[garryp6]

Apologies re the delay. I think I used 16mm2 cable. This is way too much I know but I always way over spec cabling. Excuse the mess in the picture - in one of my other threads I am replacing some of the floor due to an incorrectly sealed gas locker that let in water from day 1.



View attachment 954656

I am in the midst of changing to lithium batteries in my 2012 kontiki, Do i need to isolate the leisure charging system (whilst the engine is running and fit a b2b charger to protect the alternator? If this is the case is it just to fit a relay as above but on the p2 side of the sargent unit?

 

[Insider]

I am in the midst of changing to lithium batteries in my 2012 kontiki, Do i need to isolate the leisure charging system (whilst the engine is running and fit a b2b charger to protect the alternator? If this is the case is it just to fit a relay as above but on the p2 side of the sargent unit?

Apologies re the delay in responding. You definately need to fit a B2B if you don't have one. Lithium has low interval resistance and will take as much charge as the alternator will give, potentially causing the alternator to be overloaded if on a standard split charge relay. A B2B will deliver a more "controlled' level of charge. A B2B will also have intelligent charging whereas a split charge relay is treating the lithium as if it's an extension of the lead acid battery. Lastly most UK van manufacturers and Swift esp tend not to install adequately sized cabling. Voltage drop on the cable and potential overheating of the cabling are two issues with undersized cabling. It cost a considerable amount of time and resources to run the cabling in mine but it's a once off job.

In terms of isolating the leisure battery it depends on the system you have in the Kontiki but in general it is important to do as you will have your split charge system trying to charge your lithium and you'll have your B2B trying to charge your litium and this is not a good idea. Wheather it is better to interupt P1 or P2 I cannot answer straight off - I'll have a think about it and hopefully someone might answer as well. When I was doing my testing and did not have the relay - I just completely disconnected P1 - then I found the fridge did not work on 12V while driving and the step did not retract on ignition on.

Going back to P1 or P2, I was running my solar through the EC400(it does not however have a solar charge controller - some other versions do) but now have my solar going directly into a victron and this is directly into the battery. If you had solar going via the Sargent then disconnecting P2 would stop any solar feed.