Charging lamp.

I've just read the owners manual for my LR 110 1984 and it says..... The charging circuit will fail to charge the battery should the warning lamp blow, or words to that effect.

Now according to my wireing diagram the main charge lead goes straight to the battery, why/how does the charging lamp affect it?

I was planning to run an extra lead to the battery from my alternator, theory being that anything iffy in the wireing won't effect the charging, but if what I read is correct then I'm wrong.

What's your thoughts folks?

-- Regards. Mark.(AKA, Mr.Nice.) ___________________________________________________________ "To know the character of a man, give him anonymity" - Mr.Nice.

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Reply to
Mr.Nice.
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It wouldn't make any difference.

The alternator (actually the regulator) uses the voltage at the sense wire, provided via the charge light, to adjust it's output. Basically the alternator output is a couple of volts above the sense voltage. No volts at the sense wire = no/little volts at the output.

Modern Defenders have a resistor in parallel with the bulb. That way if the bulb blows the resistor provides a voltage reference.

To get an alternator to run at maximum, connect a wire direct from the battery +ve to the sense connector.

cheers

Dave W.

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Reply to
Dave White

Twas Sat, 14 Feb 2004 09:04:52 +0000 (UTC) when Dave White put finger to keyboard producing:

will/can this damage the battery or alternator?

-- Regards. Mark.(AKA, Mr.Nice.) ___________________________________________________________ "To know the character of a man, give him anonymity" - Mr.Nice.

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Reply to
Mr.Nice.

But expect to find a flat battery if you leave the vehicle parked for any length of time, as the rotor will be permanently live.

Reply to
SimonJ

Twas Sat, 14 Feb 2004 09:30:37 +0000 (UTC) when "SimonJ" put finger to keyboard producing:

so how can I make the alternator charge my battery whilst bypassing the normal wireing?

-- Regards. Mark.(AKA, Mr.Nice.) ___________________________________________________________ "To know the character of a man, give him anonymity" - Mr.Nice.

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Reply to
Mr.Nice.

What the lamp does is provide a circuit for a few volts to start the alternator generating. The 'negative' side of the lamp goes to an alternator terminal that rises to output voltage once it's running, and with no voltage difference across the lamp it goes out. That voltage feeds an electromagnet, which replaces the permanent magnet of a dynamo.

Reply to
David G. Bell

On or around Sat, 14 Feb 2004 09:04:52 +0000 (UTC), Dave White enlightened us thusly:

doesn't that stop the light working though? Not an issue if you have a voltmeter and know how to use it, of course.

and I'd have thought that the alternator makers are aware of any voltage drop in the bulb, and the regulator is set accordingly, so if you fool it like that, you may overcharge the battery.

Reply to
Austin Shackles

On or around Sat, 14 Feb 2004 09:39:39 +0000, Mr.Nice. enlightened us thusly:

connect the alternator "small" terminal to the ignition live feed (fuel cut-off solenoid feed for a diesel). The it'll only be live when the ignition's on, same as normal, but bypasses the lamp/wiring etc.

better bet would be to track down the fault in the normal circuit though.

you'll need a voltmeter on it if you divert around the lamp, to know if it's charging or not.

Reply to
Austin Shackles

Twas Sat, 14 Feb 2004 10:54:07 +0000 when Austin Shackles put finger to keyboard producing:

overcharge the battery, so it can damage it...

-- Regards. Mark.(AKA, Mr.Nice.) ___________________________________________________________ "To know the character of a man, give him anonymity" - Mr.Nice.

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Reply to
Mr.Nice.

Twas Sat, 14 Feb 2004 10:59:01 +0000 when Austin Shackles put finger to keyboard producing:

that sounds like a good temp, I'm not even sure there is a fault but the alternator on it was knackered when I got it, the new one I fitted lasted 2 weeks, I replaced the regulator thingy but the failed faults were the same, so there was something wrong with the alternator itself. I now have another new one (I've not heard what was wrong with the last one if anything) and it's working so far.

I really don't want some kind of wireing faults to kill this one if that's what happened last time.

I now have an extra line to the battery so there is always a battery accepting charge, won't kill it that way.

-- Regards. Mark.(AKA, Mr.Nice.) ___________________________________________________________ "To know the character of a man, give him anonymity" - Mr.Nice.

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Reply to
Mr.Nice.

The alternator regulator should be independent of the "sense" terminal, so your battery shouldn't be overcharged if you do this.

Reply to
QrizB

Take a wire from the -ve terminal on the battery, to the alternator case (or earth terminal if there is one) Take a wire directly from the +ve terminal on the battery, to the power terminal on the alternator. Take a wire from this terminal, via a fuse (5 amp) to a switch inside the car, through a bulb, then back to the sense terminal on the alternator. Make sure this switch is on with the engine running, and off when it isn't.

This way you will have entirely bypassed the vehicles own charging circuit.

Reply to
SimonJ

The alternator is sensed on the main power terminal, the feed from the light is there solely to provide a current to the rotor to start the alternator charging.

Reply to
SimonJ

_Some_ alternators have a seperate sense feed. But it's still not through the light.

It really depends on the vehicle -- it'd be fairly easy on my Lightweight -- but it might be easiest to run a new wire from ignition switch to warning light to alternator.

Some problems I had were sorted by fitting a new plug on the leads to the alternator.

Reply to
David G. Bell

Battery sensed alternators are very rare on cars, in fact I have never seen one yet! All landrover alternators are machine sensed.

Reply to
SimonJ

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