voltage problem

[frankyb]

hi everyone, it's been 2 months that I own my 69 +2 elan, what a fun car to drive. Had to spend some serious $$$ to get the car running well( new webbers, engine work, fan.) but it was worth the cash. Here in montreal canada no lotus 69 around so I been getting alot of attention on the car.Snow is around the corner, so I'm trying to get as much as possible driving before winter. I need some advise concerning the voltage, the problem is when the lights are on and the radio is on, the second I apply the the brakes, the radio goes off, it seems that the car does not have enough voltage to keep up with all the electrical systems, what would I need to change or fix??

[triumphelan]

Welcome to the "low voltage club" I to have that problem you need to sort out your earthing or may be a new loom

[Alex]

Hi Frankyb,

Given that the battery is in the boot and the headlights, which are a high current item, are at the other, there will be voltage drops through the wiring ans switches etc.

If originality isn't an issue, then I would first ensure that all earth points are clean, rust free and protected with silicone grease etc. Second, a high current relay could be fitted with the headlight suppy taken from the battery terminal on the starter solenoid with much heavier guage wire than standard.

This would provide only 1 switching point between the battery and headlights and a much reduced voltage drop due to the heavier wire.

I can draw a diagram if needed.

Alex

[peterako]

Hi Frankyb!

I heartily agree with Alex, with a strong focus on relaying....

Relaying the headlights (and later the rear lights too) on my +2 made a huge difference to a couple of things.

1. Voltage irregularities
2. A VERY SCARY THING BEST AVOIDED by using relays! (see below)

Apparently 2 above is a common enough thing.

Nearing home, on a very dark night, with headlights and high beam on a nice twisty road....

Lights go off
Totally

Luckily I had my wits about me and knew the road like the back of my hand.
I managed to stop. Then, shortly after the lights came on again....

When I got home I investigated.

The headlights, in standard Lotus wiring run through a thermal switch.
This means that it is NOT unusal for the headlights to switch themselves off now and then, seemingly at will
(Actually, when the thermal switch decides that the wiring is too hot)

So, if you're considering driving at night AND staying alive I highly suggest you power the Headlights using relays to carry the current rather than the original wiring. Use the original wiring to switch the relays.

A simple enough electrical job that could save your life.

Let me know if you need help with working out how to do it.

Take care,
Peter

[Frank Howard]

I thought these cars came from the factory with headlight relays. Am I missing something?

[frankyb]

Thanks everyone, I think I will change all the wiring , lots of loose and disconnected wires around,.

[Alex]

There is a relay hidden under the dash on early +2's but the output still goes through the dip switch. A relay down stream of the dip switch with beefed up wiring is the best option, keeping the headlight and dip switch as control lines for the relay effectively.

Hope this makes sense!

[Frank Howard]

There is a relay hidden under the dash on early +2's but the output still goes through the dip switch.

Then what is this relay for

[RotoFlexible]

There is a relay hidden under the dash on early +2's but the output still goes through the dip switch.

Then what is this relay for

On my car (S2, 2-seater), that relay controls power to the headlights (low and hi beam) based on the position of the headlight pods. Pods down, microswitch open, no lights. (Or, it used to - I have individual relays for low and hi beams now, fed through the dip switch which carries a much lower current than it was designed for.)

[Frank Howard]

On my car (S2, 2-seater), that relay controls power to the headlights (low and hi beam)

Andrew,

Are you sure the relay controlled both low and high beams?

[RotoFlexible]

On my car (S2, 2-seater), that relay controls power to the headlights (low and hi beam)

Andrew,

Are you sure the relay controlled both low and high beams?

Yup. The relay is fed from the main lamp switch and controlled by the headlamp microswitch. Its output goes to the dip switch and then to the low or high beams, depending on the position of the dip switch.

You may be thinking of the "relay flashing main beam" which is a separate relay, located (I believe) up near the left headlamp pod where its microswitch lives.

[alan71]

Andrew?s right, both the main lamp switch and the dip switch carry the full current to the headlamps, only the micro switch has the benefit of the lower current to the relay coil. Later models had separate relays for main beam and dipped.
I don?t know how this compares to a +2.

Alan

[Frank Howard]

Andrew and Alan,

My car is later, so it came with seperate relays for hi and low beams. Thanks for the education!

[denicholls2]

Hi Frankyb,

Given that the battery is in the boot and the headlights, which are a high current item, are at the other, there will be voltage drops through the wiring ans switches etc.

If originality isn't an issue, then I would first ensure that all earth points are clean, rust free and protected with silicone grease etc. Second, a high current relay could be fitted with the headlight suppy taken from the battery terminal on the starter solenoid with much heavier guage wire than standard.

This would provide only 1 switching point between the battery and headlights and a much reduced voltage drop due to the heavier wire.

I can draw a diagram if needed.

Alex

40-year old Lucas wiring has a number of issues beyond the argument that it wasn't adequate even in its day. It seems counterintuitive, but a weak connection generates more wire heat than a good one, because the bad connection arcs as it is disrupted, creating a mini-arc welder in your loom. The excellent conductivity of copper takes care of the rest.

I'll probably hear other responses to suggest that the sleeping dogs be left lying because these connectors weren't really designed for reuse, but my own experience is that cleaning all of the bullets and applying Vaseline to them before reassembly made a very large difference in overall electric system reliability, enough that I didn't use the rewiring kit I bought.

Here in the U.S., RD Enterprises carries bullet overhaul kits for the next better step. If you're really ambitious, solder connections are better than crimped ones but you need to get the wire really clean before you start.

I also second the idea of providing relays wherever high current is involved. Do be very careful in running the current supply line to avoid chafing points and make sure it is a suitable gauge with quality insulation (recommend 10 gauge). This wire is constantly live unless relayed again at the battery to the ignition switch, and extra care must be taken to avoid any grounding possibility.

[LotusNWT]

Hi

I don't have anything to add...(I am dealing with my own battery draining gremlin) Just wanted to say Hi to fellow Canadian plus two owner. I have a 68 and am rather curious as to how many are actually left in Canada.

Glen