OK
Totally puzzled by the split charge system. Aux battery seems to be getting no charge now and the fridge drains the starter batteries. Have I just reconnected my batteries incorrectly, it seemed OK once upon a time in the past.

Running 2 Optima red tops + optima yellow deep cycle with older model National Luna split charge management system. Further complicated by big winch requiring battery overide and isolating key thingy.

My electrics guys in Cairo would love a circuit diagram of how this should be set up before he tears into it. I've found some stuff on N Luna site, but not really appropriate to my cicumstances.

If any one can be helped it will be much appreciated and earn credits for Egyptian visits.

JT

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JT http://leeandjames2013.blogspot.hk/

Hi Jamie,

Who did the opriginal wiring? Iff they haven't explained what they have done or provided a wiring diagram the only option is to trace the wires back one by one and also check the National Luna site for their recommended wiring.

Which model split charging system have you got?

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Cheers,

Julian Voelcker
Overland Cruisers - Specialising in Land Cruiser preparation and servicing.

Thanks..
for the reply Julian. Reliable as ever. Not sure how us idiots would cope without the likes of you, Roman and the like.

I'll try and get a model number, although it's more likely my local electrical guru will have to spend a day tracing everything. Oh no, thats 5 quid. Oh there are many great things about living here.

Although our latest visitors will disagree as they've been turned back by Alexandria customs and told they must return to Aswan to sort out their papers.

Thanks again

JT
PS not sure of the model number but it looks like Untitled Document

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JT http://leeandjames2013.blogspot.hk/

Morning Jamie,

Have you checked out the National Luna site - Nationa Luna - Downloads - they have a few sets of instructions there.

If Frogs did the wiring I doubt there would be the slack in the system to wire the batteries incorrectly - all you could have done without causing bigger problems is cross over the negative or positive terminals of the two batteries, anything more would have sent sparks flying.

I would be more inclined to suspect a fault in one of the batteries or the alternator. The split systems I have instaled don't normally affect the standard vehicle charging system - they are more designed to channel charge to the 3rd battery.

Another thing to check is the earths to make sure that they are actually earthing properly.

Good luck.

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Cheers,

Julian Voelcker
Overland Cruisers - Specialising in Land Cruiser preparation and servicing.

These systems aren't that complicated. There's an input wire from the chassis battery or alternator output (does your alternator have an integral rectifier with only ONE fat wire leading out or a separate rectifier with two or three fat wires? There may be one or more thin wires going to the alternator as well). Then there's an output wire going to the extra battery(s). The device senses the chassis battery voltage and closes a switch when the voltage is at least 13.7. That cannot occur when the engine is off since a charged 12V battery will be at 12.6-12.7V at rest, but the alternator usually puts out 14.2V if it can keep up with demand. Some of these split charges (Sterling's for sure) increase the voltage slightly to help charge the "house" battery(s).
The ground is very important. Make sure the ground (earth) from the house battery goes to the right place, possibly the earth of the chassis battery.
Check the voltage of both batteries at rest (engine off) and the voltage of both after the motor is running for 5 minutes (Sterling's system gives 2.5 min to charge the chassis battery before closing the switch) at least at a fast idle, with and without the lights and AC on and let us know the results. Preferably with a digital voltmeter.
It's also possible though unlikely this is a primitive device which is a solenoid switch activated by the ignition switch. In which case if the (thin) input wire supposedly from an ignition voltage is incorrectly connected to a constant 12V souce the device will always be operating and the fridge will run down your chassis battery. But from what I read on Nat'l Luna's site the gadget depends on getting at least 13.7V, which should protect against this latter problem.
Sorry for the length.

10 min later - I checked their site. It's a simple solenoid but it is controlled by a solid state voltage sensor - on at 13.1V, off at 12.65V. I suppose it's possible to get the input and output wires reversed, they are both red. If the solenoid terminals have welded themselves shut thru arcing it might be possible to produce the situation described. Alternatively, if the chassis batteries are severely discharged the house battery wouldn't get a charge till the chassis batteries got over 13.1V for a few minutes.

Charlie

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Unimog U500 w/Unicat

Jamie,

Have you checked the diagrams on the NL website (configuration 3)?

Nationa Luna - Downloads

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Roman (UK)