ignitiion live? where?

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Mpower!

Active Member
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Ive got round to doing my X-ENG split charge system and its all wired up but to make the relay switch over i need to find a " Ignition Live" it says in instructions.

1) Where will i find one?

2) it says if you cant find one use any live?? :confused:

thanks again
 
You are better off using the alternator charge light as a trigger (if its the trigger you need) for your split charge,that way the second battery only links when the alternator is charging.Otherwise poke around the fusebox or piggyback onto the cigarette lighter supply,or indeed anything else that comes on with the ignition.

Probably the best thing you can do is do a search on split charge,theres a few articles on it on here,and I reckon you will be convinced to do the first thing above.
 
there is no such thing as an alternator charge light on a D2 which is why they say you have to find an ignition live? is there anythink else that i can piggy back onto in the engine bay as ive only just sealed up my bulkhead from relocating my ecu?
 
apparently theres two power cables going in the head unit ones a constant live and ones an ignition live? according to X-ENG
 
hi mate

you need to finsd something that comes on only with ignition really.

does a disco 2 have a fuel pump? if so, that could be good.

what you really want is something which goes live when the engine is running. electric fuel pump, or diesel shut off solenoid would be ideal.

how does the alternator light work on a d2 then?

personally i would work hard to find something that is live ony when the engine is running, otherwise the split charge kinda defeats the object!! :D
 
hi mate

you need to finsd something that comes on only with ignition really.

does a disco 2 have a fuel pump? if so, that could be good.

what you really want is something which goes live when the engine is running. electric fuel pump, or diesel shut off solenoid would be ideal.

how does the alternator light work on a d2 then?

personally i would work hard to find something that is live ony when the engine is running, otherwise the split charge kinda defeats the object!! :D


hello mate you sound like you know what youre talking about!

why does it only need to go live when the engine is running?
and isnt the radio only live when the engine is running?

as you can tell im no good with electrics! so all help is great thanks :)
 
yu only want it live when engine is running, so that the alternator can charge it. If yu link the batteries when the alt is not charging, one battery can drain the other.

as for radio - try switching the ign to the first (aux) position and see if the radio works :D. also the ciggy lighters.
 
If you require a switch activated 'only' with the engine running, then remove the oil pressure switch and screw in a T piece and then refit the switch and also fit a new switch into the remaining outlet, the new switch will then switch a changeover relay that is supplied from an ignition powered circuit.

Therefore relay is operational only when the ignition is switched on but drops out ie. changes over when the oil pressure switch opens as soon as the engine starts running.

You could always use the existing oil pressure switch, still using a changeover relay but after fitting a "circuit blocking device" ...... a diode :)
 
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Right ive taken the cable through the hole in which i bought my ecu exstention through the bulkhead and connected it up to the red power cable of my head-unit.

which had no volts when the key was out the ignition and twelve when the ignition was on.

does that sound right? and secondly when i checked the batterys they are now both putting out 13.9 volts when the engine is on, is that right?

i thought it was supposed to charge one and then the other?
 
Read the article,it makes it all a bit easier to understand,but basically the relay is just a heavy duty switch that is operated by that 12v ignition live.....you turn on the ignition,12v goes to the relay,the switch closes and your 2 batteries are now linked.Simple as that.The actual point where the link up takes place is decided by when that 12v goes to the relay,hence the different suggestions of what live to use - whether the engine is running or not when the switch is made.If you want to get the much advertised priority charge,that is,starting battery gets the charge until "full" and then secondary battery gets it,you need a more complex system,such as a VSR.

There is much debate on whether VSRs (voltage sensing relays) can reality supply this,but thats what the adverts tell you.Then you get into the realms of diode packs and charge priority controllers like the fancy yacht ones.

Here is a link to a 12v forum thread about this very subject....

split charge, voltage sensing
 
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