Searle Safari Split Charge

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soldiersteve
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Joined: Thu May 03, 2018 2:53 pm

Searle Safari Split Charge

Post by soldiersteve » Sat May 26, 2018 9:53 pm

Hi All

My Searle Safari has the capacity for two batteries, one in the engine bay and the second under the passenger seat. The space under the seat is currently unoccupied. Also in the box of bits that came with it is a Lucas 7RA 33335A split charge relay. I have also read that Searle offered an extra battery with split charge system as an option.

I would hope that this would be something fairly easy to restore and is something I find a particularly attractive idea as my 101 amby has this and has been useful in the past when I've managed to flatten my main battery - I just swap them over and off I go.

However I have no idea at all how to wire it in and none of the wiring diagrams I have managed to find show how this can be done. So does anyone out there have any idea how to go about this, and besides the spare battery, is there any other components I am likely to need.

Thanks

Steve
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RMS
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Joined: Wed Feb 15, 2012 12:02 am
Location: Near Wakefield, UK, in God's own Country!

Re: Searle Safari Split Charge

Post by RMS » Sun May 27, 2018 9:07 am

Hi Steve,

The Lucas 7RA 33335A is a heavy duty relay, switched on by the output (charge light terminal) of the alternator.
Very simple and the way things used to be done.

One of the problems with that type is that your aux battery is switched in to the charge circuit as soon as you start the engine.
If your main battery needs charging it won't get the full charge current as your alternator is charging both.

Modern split charge relays are voltage sensing, which means your main starter battery is charged first, then, when it is fully charged, the unit starts charging the aux battery. They also don't need to tap in to the alternator charge light circuit.

If you want to use the original relay, HERE is the basic diagram - If the terminals on your relay are marked differently, let me know and I'll see if I can work it out.

If you want a modern type, DURITE are good.
If you search ebay for split charge relay, there are some kits using this relay, or a clone of it.

I've used a cheaper version in the past, but after two failures I've gone over to the Durite ones.

Hope that helps,
Robin.
1967 109" Carawagon 200TDi
1972 109" SW Carawagon 2.5NA
1958 109" Carawagon 2.25P (project)
1972 109" Carawagon 200 or 300TDi (project)
1974 Dormobile 2.25D (project)
(Robin on S2C forum)
soldiersteve
Posts: 12
Joined: Thu May 03, 2018 2:53 pm

Re: Searle Safari Split Charge

Post by soldiersteve » Sun May 27, 2018 9:15 pm

WP_20180527_21_04_26_Pro.jpg
Hi Robin

My relay has two large terminals and two small terminals. The large ones are marked C1 and C2, the small ones are marked W1 and W2. I guess the W1/W2 is the switch and the C1/C2 is for the connection between the positive terminals on the batteries.

Steve
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RMS
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Joined: Wed Feb 15, 2012 12:02 am
Location: Near Wakefield, UK, in God's own Country!

Re: Searle Safari Split Charge

Post by RMS » Sun May 27, 2018 11:38 pm

Ah, ok, the 'old' Lucas terminal designations!

W1 & W2 are the 'windings', ie, coil, to operate the relay.

C1 & C2 are the 'contacts'.

So, connect W1 to your alternator charge light lead via a 5A fuse, and W2 to earth.

C1 to your main starter battery +Ve via a 30A fuse, and C2 to your auxiliary battery +Ve via another 30A fuse.

The wire to the alternator charge light lead and to earth can be thin wire, 0.65mm² or 1.0mm² or as it's carrying a very small current, but your battery leads need to be rated for at least 42A, 6.0mm².

Cheers,
Robin.
1967 109" Carawagon 200TDi
1972 109" SW Carawagon 2.5NA
1958 109" Carawagon 2.25P (project)
1972 109" Carawagon 200 or 300TDi (project)
1974 Dormobile 2.25D (project)
(Robin on S2C forum)
soldiersteve
Posts: 12
Joined: Thu May 03, 2018 2:53 pm

Re: Searle Safari Split Charge

Post by soldiersteve » Mon May 28, 2018 6:12 pm

Hi Robin

I'm not really sure I get this as it seems to me this system would discharge the main battery if accessories were used when the engine is not running.

If I understand things right the alternator charge light is only illuminated when the ignition is on but the alternator is not providing a charge. So the wire to W1(86) is only live until the engine starts. Once the alternator starts charging the power to the charge light and W1 is stopped. That must then allow the circuit between C1(30) and C2(87) to complete and the leisure battery gets charged. However this would also mean that when the vehicle is switched off C1 and C2 must still be connected as there is no feed to W1 to prevent it. So every time current is drawn from the leisure battery an equal amount would be drawn from the main battery.

As that doesn't make sense I must be missing something.

Steve
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RMS
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Joined: Wed Feb 15, 2012 12:02 am
Location: Near Wakefield, UK, in God's own Country!

Re: Searle Safari Split Charge

Post by RMS » Mon May 28, 2018 9:48 pm

Hi Steve,

The alternator W terminal is at 0V until it starts to produce charge, then it goes to 12V and so will energise your relay..

The reason the charge light on your dashboard comes on when you turn your ignition on, and goes off when the alternator is 'outputting' is that the other side of the charge light is connected to 12V positive, not earth as you might expect.
This 12V positive through the charge light provides the initial 'exciter' voltage to start the alternator output. Once it starts to output, the W terminal has 12V on it from the alternator, cancelling out the 12V on the other side of the charge light and so the charge light goes out as it's got 12V on both sides - and if you follow that, you're good to go :stars:

Not really explained well, but the basis is that you connect W1 to the alternator charge lead on the alternator side of the charge light, and W2 to earth :tiphat:

Cheers,
Robin.
1967 109" Carawagon 200TDi
1972 109" SW Carawagon 2.5NA
1958 109" Carawagon 2.25P (project)
1972 109" Carawagon 200 or 300TDi (project)
1974 Dormobile 2.25D (project)
(Robin on S2C forum)
soldiersteve
Posts: 12
Joined: Thu May 03, 2018 2:53 pm

Re: Searle Safari Split Charge

Post by soldiersteve » Mon May 28, 2018 10:34 pm

Hi Robin,

Err, yes, right, OK. THB I'm still trying to get my head round it and failing miserably but am happy to do as you say. It's going to be next weekend before I get an opportunity to do it now but will repost then to let you know how I'm getting on.

Thanks for your help an patience with me.

Steve
soldiersteve
Posts: 12
Joined: Thu May 03, 2018 2:53 pm

Re: Searle Safari Split Charge

Post by soldiersteve » Sat Jun 02, 2018 10:34 pm

Hi Robin

Well its in and as far as I can tell it works. So far all I have done is fit the relay and wire in the W side as I don't yet have everything I need for the C side but I have loosely wired a feed to C1 and put a volt meter on C2 and all seems to be well. When the ignition is off there is no current flow, when the ignition is turned on there is still no current but once the engine is running I get full power at C2.

Many thanks again for all your help.

Steve
User avatar
RMS
Posts: 2236
Joined: Wed Feb 15, 2012 12:02 am
Location: Near Wakefield, UK, in God's own Country!

Re: Searle Safari Split Charge

Post by RMS » Sun Jun 03, 2018 10:07 am

Great, glad you've got it working :cheers:

Cheers,
Robin.
1967 109" Carawagon 200TDi
1972 109" SW Carawagon 2.5NA
1958 109" Carawagon 2.25P (project)
1972 109" Carawagon 200 or 300TDi (project)
1974 Dormobile 2.25D (project)
(Robin on S2C forum)
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