Sargent Ec400 wiring (3 Viewers)

[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.