260Z Charging Light

[Rob Gaskin]

Hi Folks, I'm installing a 260Z Voltmeter in my 240Z. The Voltmeter has a charging light which us 240 owners have to live without.

Has anyone else done this and if so did you just connect the charging light to a 'switched source' and the L lead from the alternator? If so are you 'happy' that if the bulb blows the alternator will still charge? My 'Electrical manual' and the link below seems to suggest otherwise. Has anyone had their charging bulb blow? My manual shows charging bulbs with a 'bypass' resistor across them so that if they blow a small current can still flow.

Am I concerned when I don't need to be?

The alternator relies on a small current flowing through that bulb (from the source) to 'excite' it to start charging. The current flows because of a 'potential difference pd' (voltage) between the source and the alternator. When the alternator starts spinning and charging the pd reduces and the light dims and goes out as the voltage increases.

The voltmeter/ammeter swap seems reasonably easy (I'm removing all my heavy power wiring from my loom).

https://forums.hybridz.org/topic/128374-cs144-alternator-is-not-charging-battery/

 

[Turn & Burn]

Good Question!!
When I wired one in my Landrover and come to think of it my Westfield I didn’t think that deeply about it and went with the very simple wiring as you suggested based on differential voltage. It has always charged ok, but that maybe cos the bulb hasn’t blown!

 

[toopy]

I would of thought the amount of people on here that have had that particular bulb blow, you could count on the hand of someone with less than five fingers!

Think how long the bulbs are actually in use for each time you start the car, negligible use over the years.

 

[Rob Gaskin]

I would of thought the amount of people on here that have had that particular bulb blow, you could count on the hand of someone with less than five fingers!

Think how long the bulbs are actually in use for each time you start the car, negligible use over the years.

Yes I went through that reasoning too but this is a 'soft' rally car and may be used at night. Can you imagine packing up on a rally due to that bulb blowing! A 'get you out of jail' fix is to connect the L lead to the S lead but not permanently.

I need to investigate more.

 

[Turn & Burn]

I can send you over a 280z colour wiring diagram and you can trace it off there? See how they did it on there which I reckon will be the same as my late 260z.

 

[Rob Gaskin]

Ok no resisitor. I tell you what I'll do when I get the car running - I'll take the bulb out and see what happens. Hopefully nothing.

 

[Rob Gaskin]

I've had it confirmed by a professional rally loom manufacturer that he puts a resistor across the bulb. He is sending me one foc.

 

[jonbills]

I realised last weekend that the bulb in my volt gauge has failed.
it probably explains why I have to rev to 3000rpm after starting to get the alternator to start outputting anything.

 

[Rob Gaskin]

Seriously? Don't worry they are easy to change (not)!

 

[jonbills]

really really I'll prob have a go at it at the weekend.

 

[jonbills]

fixed!
It was pretty easy. I just made all the same mistakes I always make.
1) I put the bracket back on upside down on the gauge itself.
2) I put the fascia brackets on before I put the duct back in.
3) I fiddled with the map light for 10 minutes hoping I could make it work. What a rubbish design!

 

[Rob Gaskin]

So Jon, does it start charging at lower revs now on initial start-up?

 

[jonbills]

I don't know for sure - the head is off at the mo so I can't start it.

 

[Rob Gaskin]

I don't know for sure - the head is off at the mo so I can't start it.

Can't you ever stop tinkering?

 

[jonbills]

Can't you ever stop tinkering?

It's all essential engineering work

 

[jonbills]

OK, now my engine is running again I can confirm that with a working bulb in the volt gauge, the alternator starts charging as soon as I start the car.
with a blown bulb in the gauge, the alternator didn't start until the first rev past 3000 rpm.

 

[Turn & Burn]

OK, now my engine is running again I can confirm that with a working bulb in the volt gauge, the alternator starts charging as soon as I start the car.
with a blown bulb in the gauge, the alternator didn't start until the first rev past 3000 rpm.

Good result, satisfying to have a success!

 

[Bazzateer]

My charging light has stopped working but even so the alternator is putting out 14v at tickover.

 

[Rob Gaskin]

My charging light has stopped working but even so the alternator is putting out 14v at tickover.

Interesting. Is that from immediate 'start-up' ?

 

[Bazzateer]

I believe so. I'll have check it all again. I'll need to fix the light in any case.