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Split charge relay

Post by entwistlecymru » Wed Jul 01, 2015 11:00 pm
Joined: Tue Apr 07, 2015 9:52 pm
Posts: 57
This is a bit of a lazy post but basically I'll be fitting a split charge relay to my diesel van this weekend. I've read the instructions briefly and need to know if there's an ignition switched wire with no more 3v supply through it - this is what the S/C relay needs to turn on. On a petrol I'd assume this would be the ignition coil feed but being a diesel mine won't have that. Any ideas where I should start looking? I can find it with my multimeter this weekend but I have two days to get the van prepped for Billing including LOADS of welding so a head start would be great! Thanks in advance
1978 Manta SR, 1980 Rekord van, 1984 Carlton 1.8S estate, 1985 Carlton 2.2 GL estate, 1985 Carlton 2.2 CD, 1985 Manta GT, 1984 CF FF LWB minibus, 1985 CF 350, 1986 CF SWB minibus, 1987 CF 250, 2006 Triumph Tiger 1050, 2016 Triumph Thruxton R

Re: Split charge relay

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Post by Phil Bradshaw » Club admin » Thu Jul 02, 2015 3:38 am
Joined: Sun Sep 02, 2012 7:15 pm
Posts: 4673
For a split charge relay with high impedance solenoid coil (i.e. low switching voltage) one of the solenoid terminals normally is connected to the alternator warning lamp wire (brown+yellow) between the alternator wiring connector and warning lamp, the other terminal being earthed to the vehicle body.

Lucas relays -

Image

To be sure, what make and type of relay are you using?
  • What is real is not the appearance but the idea, the essence of things. Constantin Brâncuși

Re: Split charge relay

Post by entwistlecymru » Sun Jul 05, 2015 7:44 pm
Joined: Tue Apr 07, 2015 9:52 pm
Posts: 57
That's exactly what it was Phil. I pulled the engine cover off and discovered the brown/yellow wire crimp had come apart so it looks like the van hasn't been charging since I've had it! I've never noticed the batt light on at least. I tested the battery and sure enough it was pretty low - put it all back together and the engine wouldn't crank. The battery obviously decided to die there and then - better than next Friday on the way to Billing! Luckily, doing what I do, I just nipped down to my shop and nabbed a juicy big Varta battery - problem solved :D
1978 Manta SR, 1980 Rekord van, 1984 Carlton 1.8S estate, 1985 Carlton 2.2 GL estate, 1985 Carlton 2.2 CD, 1985 Manta GT, 1984 CF FF LWB minibus, 1985 CF 350, 1986 CF SWB minibus, 1987 CF 250, 2006 Triumph Tiger 1050, 2016 Triumph Thruxton R

Re: Split charge relay

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Post by Phil Bradshaw » Club admin » Sun Jul 05, 2015 10:16 pm
Joined: Sun Sep 02, 2012 7:15 pm
Posts: 4673
Second or leisure battery should be a deep cycle type and ideally there should be a 30A fuse in line between the relay and battery. 30A fuse should be adequate because deep cycle batteries shouldn't demand more than about 25A even when discharged.

If a starting battery is used as the second battery then the cable to the battery should be uprated to accommodate maximum alternator output for when the normal starting battery is well charged but the second battery is discharged, the latter then demanding pretty much all the alternator output until about half charged.

Using a starting battery as a leisure battery will significantly shorten its life if it is repeatedly discharged below 11V or left discharged for any length of time, unlike a deep cycle battery designed for slow discharge and recharge, i.e. not for starting duties unless designed as a 'dual purpose' type, e.g. for marine use.
  • What is real is not the appearance but the idea, the essence of things. Constantin Brâncuși

Re: Split charge relay

Post by Frogmanbrabs » Mon Nov 23, 2015 5:20 pm
I've just seen this advertised on ebay and I'm thinking it would solve my problem of not having any charge going to the leisure battery. Does anyone have any experience of these or any advice? http://www.ebay.co.uk/itm/141707180153? ... EBIDX%3AIT

Re: Split charge relay

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Post by Phil Bradshaw » Club admin » Mon Nov 23, 2015 9:13 pm
Joined: Sun Sep 02, 2012 7:15 pm
Posts: 4673
Smartcom voltage sensing relay I have on my CF2 has worked fine for about 2 years now.

I bought just the relay, not a kit, and used a 30A weatherproof blade type pre-wired fuseholder for the installation.

Basic set-up before connecting leisure battery to any other circuits -

Image
  • What is real is not the appearance but the idea, the essence of things. Constantin Brâncuși

Re: Split charge relay

Post by Frogmanbrabs » Tue Nov 24, 2015 11:12 am
Thanks Phil, I think I'll play it lazy and get the kit. I notice from the pic that you have both your batteries next to each other in a recess. My main battery is currently behind the passenger seat and the leisure battery is under the seat in the seating area next to the kitchen unit. While I was under the van I noticed a cradle that looked battery sized and was wondering if this was for the leisure battery. In the Haynes manual it states that the main battery is situated behind the front passenger wheel underneath in a cradle but this one seems too far back for that. Where are your batteries located? :brew:

Re: Split charge relay

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Post by Phil Bradshaw » Club admin » Tue Nov 24, 2015 12:27 pm
Joined: Sun Sep 02, 2012 7:15 pm
Posts: 4673
On all CFs the battery cradle is attached to the outboard side of the left side chassis longitudinal behind the cab step rear vertical panel.
Getting two batteries to fit the cradle is a compromise between dimensions and battery capacity; for my purposes the leisure battery doesn't have to do long spells without recharging so at 75Ah is ample, likewise the starting battery with the van having a petrol engine.

On chassis cab and chassis cowl models it's best to have access from above the battery cradle if it is to be used but on a lot of coach built motor homes this means having a hinged or drop-in panel either under existing furniture (e.g. wardrobe in Autosleeper Clubman or under seating in Advantura 5/6-berth) or in the doorway (e.g. Compass Drifter 4-berth). Access can be difficult ...

Most owners move batteries to somewhere a bit more accessible, usually within the van. This is fine as long as the batteries are secured to prevent short circuit across their terminals and vented to atmosphere outside the vehicle otherwise acid mist and fume may be released into the cab or living area: not good to breath in and can lead to local metal corrosion.

This matters more for the starting battery because it is more likely to emit acid mist and fume than a leisure battery. 'Sealed' or 'Maintenance Free' batteries normally have provision for vent tubes, either a hole or a spigot at each end of the top where vent tubes can be fitted and then taken outside the van through a suitable hole (10-15mm diameter to allow for a sealing grommet). Containment for batteries with vent/filler plugs for topping up with de-ionised water should be provided with openings to outside air, often the case when batteries are installed in the body by the manufacturer.
  • What is real is not the appearance but the idea, the essence of things. Constantin Brâncuși

Re: Split charge relay

Post by Frogmanbrabs » Wed Nov 25, 2015 12:17 pm
I measured up the 2 batteries and they won't both fit in the cradle so it looks like it's where the leisure battery will be living after I've fitted the split charge relay (I ordered the one I asked about). I'm looking at trying to make some sort of cradle for the main battery so I can move it away from behind the passenger seat. I want to fit a swivel chair for the passenger so the battery is in the way at the moment.

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