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**AndyLala** · 7 June 2006, 21:16

A little simplistic... but might help

http://www.kampenwagen.co.uk/split%20charge%20relay.htm

http://www.marcleleisure.co.uk/Sund0...itCharge01.htm

These guys do some really interesting stuff... I know its covered in green oval stuff... but its good stuff none the less.. These are very clear instructions

http://www.x-eng.co.uk/Instructions/X-Charge.pdf

**MattF** · 7 June 2006, 21:16

Originally posted by andy_enuff

Hi All, it's a long time since I posted! I have a Gen1 2.4TD surf (non efi) and am having problems with the charge lead from the alternator. When I say the charge lead I mean the lead that has minimal positive voltage until the alternator is rotating - not the one that actually charges the battery and runs the equipment!

If the Surf alternator is the same as most others, that third
connection should be the field winding. If I remember
correctly, voltage will only appear on that lead once the
engine is running, as until the field windings are energised,
the alternator rotor can rotate with minimal drag. I'm no auto
electrician, however, so I may well be completely wrong.

**andy_enuff** · 7 June 2006, 21:27

Cheers for the info guys, however I think you may have missed the point

The split charge relay is fitted and operational, just not at the right time. It connects both batteries even when the ignition is just 'on' but the engine is not started. It IS connected to the correct alternator wire, however on testing the voltage at different parts of the system with the fuse removed i get the following:

alternator side of open fuse (basically just the wire going to the alternator) 0-2.4 volts in any position except running

instrument panel side of fuse - pretty much primary battery voltage when ignition is on or off and 13.5 when engine running.

Because of the potential difference between the dash side and the alternator side (approximately 12.4v - 2.4 volts = 10v) the relay is switch when just the ignition is on.

Thus there is either a problem with the dash side of the circuit (dashboard or beyond the dashboard on the return back wherever that circuit originates) or I am not understanding.

Should the voltage be coming FROM the alternator towards negative from the alternator field winding or the other way round, from the dash to the alternator. Either way, something isn't right if that is the correct wire!

**AndyLala** · 7 June 2006, 21:47

Originally posted by andy_enuff

The split charge relay is fitted and operational, just not at the right time.

Should the voltage be coming FROM the alternator towards negative from the alternator field winding or the other way round, from the dash to the alternator. Either way, something isn't right if that is the correct wire!

So two things here.
1) yes the relay works, but not at the right time.

so, its either wired incorrectly, or something else has changed. Like a wire has been cooked.

2) according to that x-Eng diagram, and my rudimetary understanding, the current flows to earth. x-Eng recommend taking a feed from wiring between the wire from the alternator to the dash light, and taking that to earth through your sense lead on the relay.

Does that help make any sense of it?

**andy_enuff** · 7 June 2006, 22:07

Um, that's where it is...

I just don't understand why when i disconnected the dash from the alternator wire the voltage coming FROM the dash is 12v? The dash looks fine, the wiring looks fine and uncooked. I believe the dash wiring should be at 0v or close to ground. I've had the dash out and that all looks fine electrically and all of the gauges work as they should including the battery light and the other gauges attached to the same circuit board as the charge wire goes to.

Hence it poses the question i suppose: what should the voltage be coming from the dash and what could be causing it to be incorrect?

**AndyLala** · 8 June 2006, 08:49

I suppose you could try changing the relay...

Try and find one that would trip at a higher voltage...? (above 2.4v) then it would switch in the second battery at the right time...?

**MattF** · 8 June 2006, 09:02

Originally posted by andy_enuff

Um, that's where it is...

I just don't understand why when i disconnected the dash from the alternator wire the voltage coming FROM the dash is 12v? The dash looks fine, the wiring looks fine and uncooked. I believe the dash wiring should be at 0v or close to ground. I've had the dash out and that all looks fine electrically and all of the gauges work as they should including the battery light and the other gauges attached to the same circuit board as the charge wire goes to.

Hence it poses the question i suppose: what should the voltage be coming from the dash and what could be causing it to be incorrect?

If the wiring at the dash was earthed, your alternator warning
light would be on constantly if the third lead from the alternator
is a field tap, (12-14V whilst the engine is running). That is what
stops the warning light coming on. Without knowing the wiring
layout, however, the grounding arrangement I cannot say. Hope
that makes sense.

Just had a look at the wiring diagram. Block diagram, so the following
is only a vague interpretation:

The charge warning lamp should have 12V across it when the ignition
switch is in certain positions, i.e: engine running. It's diode blocked, so
current can only flow through the bulb if the output from the yellow/blue
lead on the alternator goes low, i.e: 0V. As to which ignition switch
positions 12V should be visible at the dash bulb, that I don't know. Hope
that helps.

**andy_enuff** · 8 June 2006, 17:37

That makes a lot of sense and was what I was sort of expecting - I have a suspicion that there is a diode missing somewhere or that an alarm wire has been added which bypasses this. If the charge wire does operate in this way and voltage can flow from the dash to the alternator when the ignition switch is on, then surely all of the tutorials about a relay are a little false as it will always come on when the ignition is switched into those positions (namely the pre-start/run position).

I can't even add my own diode, as this will retard the charge light on the dash, so either the tutorials are all rubbish or something is not quite right with my ignition?

**MattF** · 8 June 2006, 18:33

Must admit, I would probably suspect the ignition
switch or wiring to it. Without knowing exactly how
the alternator setup works, it is pretty hard to suggest
a workaround, but one possibility might be, if the
alternator relies on residual magnetism rather than
a supply from the dash, to pop another diode close
to the alternator allowing current to flow from the
alternator in the direction of the fuses, then tapping
the coil supply for the split charge relay from between
the alternator and the newly inserted diode. That would,
theoretically, keep the warning light function working,
but prevent the dash supply from reaching the alternator.
However, as I mentioned, that is an example which relies
on several assumptions regarding how things operate.

**andy_enuff** · 8 June 2006, 18:37

In addition to the above i note the following from the www.kampenwagen.com site listed elswhere regarding split charging. Under the section "Now to answer a question I am always being asked..." at :
http://www.kampenwagen.co.uk/split%20charge%20relay.htm.

This implies that the light bulb will munch the voltage flowing from the dash and the relay will therefore not light. I notice that on my vehicle the battery light does not light when the ignition is switched on (only when the immobiliser is on). On a surf does the battery light come on when the ignition is switched to 'acessory' before starting the engine? If so then i suspect my alarm wiring is playing about with the charging circuit and causing the battery warning light not to light thus making the realy operate.

**TonyN** · 8 June 2006, 18:50

Nah, you shouldn't get any dash lights on 'Acc' only at the second 'on' position.

**andy_enuff** · 8 June 2006, 19:55

Just double checked, nothing on Acc as per, but when in the on position without engine running

Immobiliser on: no light now - but was just battery light
Immobiliser off: Coil pre-heat and brake light, suspension switch light. Nothing else.

I've just taken apart most of the dash (AGAIN) and removed some of the older wiring that has been post fitted. I can't see anything majorily dodgy, the usual alarm wiring to the central locking, an alarm wire to the light fitting for door open snesing, and wiring for the ultrasound sensors, but I can't see why the charge business would be happening!

**MattF** · 8 June 2006, 20:45

Unrelated to the thread, but looking at your sig
and the 'flat roof conversion', might one ask how
you managed that?

**andy_enuff** · 9 June 2006, 00:33

Surf's dont like 15-20 miles an hour backwards with half lock and 'normal' suspension mode.

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ALternator charge lead

ALternator charge lead

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