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X-Charge fitting - please help!

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Hi. I'm trying to install an X-Charge split charge system on my 110. It's an '86 110 with a 200tdi retrofit. I've never done anything like this before and I'm sort of stuck.

The instructions say to tie into the smaller wire coming out of the alternator. I've found that wire, so that's fine, but do most people splice the wire in the engine bay or after it's come into the cab? I've tried to follow it into the cab but it's a huge mess of wires as you'd expect from a 20 year old car with an engine swap and a left hand drive conversion (all done by previous owners).

The instructions say that this wire goes to the battery charge indicator lamp on the dash. Can or should I find the wire that goes to the charge indicator lamp in my dash? I read somewhere that that was a bad idea but I have no idea why...

It seems like it would be easier to splice into a wire that's already in the cabin, as then I don't have to figure out how to get a wire through the bulkhead, and worry about it melting on something or getting shredded somehow. But I just have NO IDEA which wire in the cabin would work, or even how to figure that out!

Also, am I better connecting my negative battery terminals together, or separately grounding each battery? I thought separately grounding each would be better but the instructions say to connect them together.

Thank you very very much,

- Andrew Clarke.

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I got this sorted out. I used the green wire from my rear wiper switch to trigger the relay. It seems to be working.


- Andrew.


I dont know the X-Charge system, but all split charge systems basicly functions more or less the same way.

Some kind of signal is used to trigger a solenoid so that the main battery and aux battery is joined together.

The signal for this solenoid can be taken from the alternator - or from any ignition switched supply. Taking the signal from the alternator is probably the best.

If you take the trigger signal from the alternator then the two batteries will only be joined together WHEN the alternator is charging. If you take the signal from an ignition swithed supply the two batteries will be joined together whenever the ignition key is turned - regardless of the alternator is charging or not.

By taking the signal from the green wire going to the rear wiper you have effectivly created a ignition switched split charge, instead of a alternator switched split charge system.

(Green wires are ignition switched according to wiring standard BS-AU7 - se below for full list)

On the alternator you will find at least three terminals, the big B+ where you connect the positive lead from the battery (joined at common point on starter solenoid) and the W+ where you connect the tachometer and the D+ where you connect the charge warning lamp.

The D+ is actually a lower rated "copy" of the B+ circut. The main purpose of the D+ circut is to provide input current to the regulator and to provide a positive feed for the charge warning lamp.

The charge warning lamp is on one side connected to the positive terminal on main battery, on the other side connected to the D+ terminal on alternator. When the alternator is not running, the regulator effectively shorts the D+ and field windings, thereby running a current from the positive battery terminal over the charge warning lamp to the alternator field windings and from there to vehicle earth. The charge warning lamp will then light up.

When the alternator is running the current provided from the main battery terminal will exite the field windings, and the alternator will begin to produce current. The charge warning lamp will then receive a positve feed from both sides which is why it stops to light after a few seconds after the engine is started.

The D+ terminal is therefore important for any split charge system, in providing a definitive signal for when the alternator is running.

Best practice is to connect the two wires ON the D+ terminal on the alternator. Then the modification is clearly visible for all others doing repair work to the car. The wire should (of course) be fused. 5amp fuse will be more than enough.

The two batteries (main and aux) should have common ground (vehicle earth)

A low cost split charge system can be made using a small 30 amp automotive solenoid.

Terminal 86 on the solenoid shoud be connected to D+ on the alternator. This wire will only provide a small current to trigger the solenoid so can be made from 1.5mm2 cable and should be fused with a 5 amp fuse (as close to the alternator D+ as possible)

Terminal 85 on the solenoid should be connected to vehicle earth (1,5mm2 cable will do fine)

Terminal 30 on the solenoid should be connected to main battery positive terminal. 30 amp fuse as close as possible to the positive terminal on battery. Use 6mm2 cable.

Terminal 87 on the solenoid should be connected to the aux battery postive terminal. 30 amp fuse as close as possible to the positive terminal on battery. Use 6mm2 cable.

The two batteries should both have their negative terminal connected to vehicle earth.

Full list of BS-AU7 colour codes included for reference purposes:



Black: All ground connections

Black/ Purple: Temperature switch to warning light

Black/ Green: Relay to radiator fan motor

Black/ Light green: Brake switch

Black/ Light green: Brake differential pressure valve to warning light

Blue: Headlamp connections

Blue: Headlamp switch to dimmer switch

Blue White: Headlight high beams

Blue/ White: High beam dimmer switch to high beam indicator lamp

Blue/ White: Dimmer switch to long-range driving light switch

Blue/ Red: Headlight low beams

Brown: Main feed from the battery. No switches or fuses

Brown/Yellow: GEN to volt. Regulator

Brown/ Blue: power feed to headlamp switch

Brown/ White: Ammeter to main alternator terminal

Brown/ Yellow: Long-range driving light switch to lamp

Brown/ Yellow: Alternator to 'no charge' warning light

Brown/ Purple: Alternator Regulator feed

Brown/ Green: Fuse to horn (No relay)

Brown/ Lt. Green: Windscreen wiper motor to switch

Brown/ Black: Horn to horn button (no relay)

Green: Ignition switch controlled wiring for auxiliary devices, eg wipers, flashers, etc

Green/ Black: Fuel gauge to fuel tank unit

Green/ Blue: Water temperature gauge to temperature sender unit

Green/ Brown: Switch to reverse lamp

Green/ Red: Direction indicator switch to left-hand flasher lamps

Green/ Purple: Stop lamp switch to stop lamps

Green/ White: Direction indicator switch to right hand flasher lamps

Green/ Yellow: Heater switch to slow speed on heater motor or for single speed motor

Green/ Gray: Heater switch to high speed on heater motor

Green/ Orange: Low fuel level switch to warning light

Light green: voltage stabilizer to instruments

Light green/ Black: Windscreen washer switch to motor

Light green/ Blue: Flasher switch to left-hand flasher warning light

Light green/ Brown: Flasher switch to flasher unit

Light green/ Purple: Flasher unit to flasher warning light

Light green/ Orange: Rear window washer switch to motor

Orange: Wiper circuit

Orange/ Black: Wiper switch to to motor parking

Orange/ Blue: wiper switch to low speed on motor

Orange/ Green: Wiper switch to high speed on motor

Orange/ Yellow: Rear wiper switch to rear wiper motor

Orange/ Light green: switch to rear window motor parking

Purple: Accessories fed direct from battery via fuse (Always live)

Purple/ Brown: Horn fuse to horn relay when horn is fused separately

Purple/ Red: Switches to map light, under bonnet light, glove box light and boot lamp when fed direct from battery fuse

Red: Tail lights, instrument lights, parking lights and side markers

Red/ Yellow: Fog light switch to fog light or front fog light fuse to fog lights

Red/ Blue: Front fog light fuse to fog light switch

Red/ Brown: Rear fog guard switch to lamps

Red Orange: Power to rear fog guard lamp fuse

Red/ White: Fuse to instrument lamp switch, Instrument panel lamps

White: Ignition circuit, no additional switches, not fused

White: Power to coil

White/ Black: Ignition coil to distributor

White/ Black: Distributor side of coil to tech impulse sensor

White/ Brown: Oil pressure switch to warning light or gauge

White/ Pink: Ignition switch to radio fuse

White/ Red: Ignition switch or starter switch to starter solenoid

Yellow: Generator connections wired through the ignition switch

Yellow/ Green: Dynamo 'F' to control box 'F' Alternator field 'F' to control box 'F'

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