Replacing Split-charge Relay

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Mark S
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Replacing Split-charge Relay

Post by Mark S »

Drove off today and a few minutes in acrid smoke was coming from under the driver's seat. It appears that my split-charge relay is fried and the leisure battery is not putting out any Voltage. I assess, being 9 years old, it has failed internally and drawn too much current from the system, overloading the relay.

I have seen conflicting information about how the thing is wired up. But does anyone know if this bad boy is a good replacement? https://www.brickwerks.co.uk/relay-12v-30a-5-pin.html" onclick="window.open(this.href);return false;

I imagine 85 and 86 are on the alternator/ignition light circuit as the trigger and 30 is connected to the leisure battery. When the engine is not running, the mains charger on 87a is connected to the leisure battery through 30, and when the relay closes after starting the engine battery on 87 is switched in instead.

Have I got that right, or any other top tips?
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937carrera
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Re: Replacing Split-charge Relay

Post by 937carrera »

Nearly, but not quite.

First of all terminal numbers https://en.wikipedia.org/wiki/DIN_72552

Most split charge systems are 4 pin relays, wired as follows

Terminal 86 - Switched feed from switch, low current
Terminal 85 - Earth route for low current side

Terminal 30 - Battery / high current feed
Terminal 87 - Switched high current supply to device

There is no circuit until power is applied to terminal 86.

In a 5 pin relay terminal 87b, passes current from terminal 30 when the relay is not energised, when energised the current from terminal 30 is delivered to pin 87

So, the simple question is, do you have a 5 pin or a 4 pin relay
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Mark S
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Re: Replacing Split-charge Relay

Post by Mark S »

5 pin. VW part 411915511B.

The terminal numbers are obliterated through heat but from what I can work out from the wiring already in place:

There is a blue wire (or rather a pair of blue wires with a piggyback connector). This is part of the trigger circuit and goes to 85 or 86 (I don't think it matters which). There is also a darkish, thinnish wire (black?) that is also part of the trigger circuit goes to the other trigger terminal. Pretty happy with this pair.

There is a solid red wire that I'm pretty sure goes to the positive terminal of the leisure battery. I imagine this needs to go to terminal 30 so it always gets either of the two feeds below.

There is a feed from the BBB on a red/black wire. I should think this goes to terminal 87a so it connects to the leisure batt when the relay is (normally) open and means it can be charged from the mains while static.

There is a feed from the engine battery on a red/white wire. If this goes to the terminal 87 it would be connected to the leisure batt as the relay closes after the engine starts.
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Mark S
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Re: Replacing Split-charge Relay

Post by Mark S »

Further info: I have just learned that this relay in fact has two 87 terminals, making it in effect a 4-pin device. I believe that the two 87 pins link permanently the red/black charging wire from the BBB mains charger and the red/white always-on 12V feed from the engine battery, so the engine battery can be charged from the mains. The leisure battery goes on pin 30 as thought so it gets connected to the engine system when it is running.

Meanwhile, the leisure battery should have its own permanent feed from the BBB on a red/yellow wire.
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937carrera
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Re: Replacing Split-charge Relay

Post by 937carrera »

I think you've got it sussed.

I seem to recall from another post that Westies are wired differentlly with two live outputs. Jusdt had a look at the wiring diagram I posted in the other thread and it's so that the starter battery is charged by the battery charger when on hook up, so it is a 4 pin relay with a direct pass through connection on the terminal 87 side.

The part number is from a type 4 car as it starts 411, how curious, wonder what it was used for on that, I should know as I have had four.

Anyway, I think you know what you need now, if Brickwerks don't have one try these people https://www.12voltplanet.co.uk/relay-guide.html
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
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Replacing Split-charge Relay

Post by clift_d »

There's a recent thread below that has most of the info you need including a link to the Westy circuit diagram, and the correct Durite part number for a replacement.

http://forum.club8090.co.uk/viewtopic.php?f=39&t=164129

You are correct in that the relay should have two 87 terminals, i.e. no 87a or 87b. The Westy specific configuration allows the BBB to simultaneously charge both the starter and leisure battery when the van is on a hook-up, as you will see from the wiring diagram.
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937carrera
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Re: Replacing Split-charge Relay

Post by 937carrera »

:ok

Didn't realise that thread was so recent, seemed like months ago :oops:
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Re: Replacing Split-charge Relay

Post by clift_d »

:D

Time flies when you're having fun.
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937carrera
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Re: Replacing Split-charge Relay

Post by 937carrera »

I'm not so sure doing bodywork is fun yet. :)

Anyway, I have found out the original VW use for this relay - fuel pump and auxilliary air regulator on the 411 / 412

Another nugget of useless information stored away for a few milliseconds of time :)
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Re: Replacing Split-charge Relay

Post by CovKid »

A 30amp relay is insufficient for that job. It should be 40amp as a minimum.
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Replacing Split-charge Relay

Post by clift_d »

The Durite 0-727-32 relay is rated by Durite on their website at 40A - see link below. For some reason however the product image the've used has a 30A marking on the side - I have no idea why this is the case?

https://www.durite.co.uk/itm/Mini-Twin- ... 40A/072732
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Re: Replacing Split-charge Relay

Post by 937carrera »

Let's try and make this a second definitive reference thread. :)

The original VW part number is 411 915 511 B and that part is a 30 amp relay. I then discovered here http://www.van-cafe.com/camper-applianc ... tery-relay the Bosch equivalent part number is 0.332.019.150

Doing a search for that part number throws up https://www.arc-components.com/0-727-32 ... -2157.html which is for Durite 0-727-32 which is actually a 40 amp equivalent

E D I T. beat me to it
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Re: Replacing Split-charge Relay

Post by CovKid »

Aye, in an ideal world 30amp should be enough but seen enough burnt out relays to suggest that 40amp should be the starting point. A few years ago I picked up a Bosch 80amp relay for £1 on a boot sale. Bigger amperage relays also have more substantial terminals for power-carrying side. 30amp ones tend to be same sized spade terminals on all four - says much. :shock:
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Re: Replacing Split-charge Relay

Post by Mark S »

I just bought a Bosch 30A relay to replace the old one. I could have gone higher but figured it had done the job for 31 years and only failed because the internal resistance of the battery collapsed and the circuit was massively overloaded. I also bought a 30A inline fuse to put in the charging line to the leisure batt so this doesn't happen again. If this blows then I'll think again.
1987 Westy Joker

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