Right! It's electricals weekend here. I installed two high mount rear stop lights today, which work, no smoke released. I've got some H4's here, I bought them back when the £ was nearly twice as much as it is now. I've finally gotten sick of having them lying round. I've bought most of what I need to install them, but, despite a very good 'How To', and quite a few threads, I think there are still a couple of pieces of the puzzle missing.

Firstly, a link to the 'How To'!
Secondly, Wombat's H4 thread, which includes a schematic. I believe the schematic is, however, different to what's described in the 'How To', as the 'How To' doesn't use relays with pin 87a, and the Low Beam does not connect to the High Beam Relay.
I also found this thread interesting, and also found clues in this thread.

I'll try to be brief with my questions!

1. The 'How To' says to use Minimum 5mm wire for all new connections. What's the rating of this wire..? I wanted to check because my local shop didn't sell anything bigger than 4mm (15 amp). If running 60W high beam (my lights came with 55/60 bulbs), at 12V (I realize they can run higher than that) that's only 5A - per bulb. So that's 10A total draw. I'm guessing the 5mm wire - which again, I'd guess is more like 20A - is to allow 90/100W bulbs..? Or is it just safety margin?

2. The 'How To' says, regarding the power wire (fed from the Solenoid Battery), Each of these wires has to go through a fuse. What size should the fuse be? My fourth link implies it should be 30A..? Or, should it match - or be lower than - the rating of the 5mm (or larger) wire..?

3. Where do people normally locate all this? I'm now getting the impression people hang it around the horn? I was hoping to have it inside (planning to install a dash, no room around the horn!) - any reason not to do that?

Just for general info, I've got 2*Narva 68044BL 12V 40/30A 5 Pin (with Resistor) relays. They have pins 30, 85, 86, 87 and 87a. I think I've got their connections sorted in my mind, going off the 'How To' (i.e. ignore pin 87a), just want to make sure I get all the parts around them right.

The bottom pic is my basic schematic for what you need. The top is just the pinouts of a standard relay.

I forgot to add in the fuse that goes from + to the relay, the general rule of thumb is to have a fuse double of what the steady current flow is, so if your lights need 10A use a 20A fuse.

87 and 87a on a standard relay are the same output so i put 1 headlight wire to each.

You will need to do 2 relays so both low and high beams work. They can share the same battery power supply to make it a bit easier and you will only need 1 fuse then.

Hope this helps.

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Dean Hutton's first car was a Mini.

Hi,

Here's the setup I use, and it appears to be similar to the one pooee and some others have mentioned :



I like this setup as it requires NO MODS to the harness - I just make little adapter cables to interface between the original low/high beam feed from the harness to the switching input on the relays.

As for the other Q's...

1. As long as it's a short run, 4mm should cope fine.
2. I consider fuses only as a "wiring saving device" so choose a fuse rating lower than what your wire smokes at 30A should cover it all easily, and still give short-circuit protection.
3. On my roundy it was located on the drivers flitch panel, near the solenoid. This was convenient as the harness feeds came out here as well.

hth

cheers

Jacob

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'72 Clubman Van - 1022cc, 295 head, 731 cam - Daily Driver
'69 Morris 1100 S - Dinged by a bus, in shed under repair
'64 Morris 1100 - Early 1100, long term project

Isn't 87a a normally closed contact and 87 normally open? Wouldn't putting one headlight to each cause one to come on with the headlight switch off?

Andrew

Thanks for the responses guys. I didn't get to it today... Not to worry. There's always next weekend, or one afternoon.

Now... On the responses... Andrew, you're right. 87 and 87a are different - 87 is, without current, closed. 87a without current is open. At least, that's the difference between the two on mine. Convertible Mini has noted in a few threads though (I think including perhaps my third link in the first post) that some relays have 2 pins marked 87 (not 87 + 87a , but 87 + 87). In that case, what Tombo's described would work. Convertible Mini says to use one for High Beam and the other for Driving Lights if you have them.

Tombo, so... Fuses. If you're saying a 20A fuse for 10A of draw, that would mean 25A wires, right..?

Jacob, when you say 30A should cover it... if I'm running 15A wires (4mm), then how does the 30A cover it..? That's what I was wondering - I was thinking about the fuses as wire saving devices, so it would make sense to have nothing bigger than a 15A fuse on a 15A wire...
I had to go Google Flitch panel... I've no idea where the solenoid is on that panel - I'll have to go digging. I haven't done a heap of electrical stuff before.
And I think your diagram is the one that matches the 'How To'.

On a standard relay they are the same - linked internally so both behave the same.
On a changeover relay they work how you described, the output is through one or the other, so not much good for lights....
Unless you use one standard relay to provide the power to a changeover type, the changeover type then switches between high and low beam depending on the minis original high beam wire. I can draw a pic of this if you want too.

I like relays, you can make them do good things

_________________
Dean Hutton's first car was a Mini.

So... No further answers on wire size vs. fuse..? Just checking...

Your wires must be able to handle more than the fuse, otherwise the wire will burn before the fuse.
So if you have 20A fuse, pick 30A wire or bigger.

_________________
Dean Hutton's first car was a Mini.

Tadhg, if you run into problems on the weekend let me know. I love relay's and the cool things they can do

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"In two years time your car will be like a lady's clothes, out of date, my car will still be in fashion when I am dead" - Sir Alec speaking to Pininfarina

Well, I had a computer case fan die last night (not this computer, the one that backs up this computer), so I had to run into town this morning... Where I bought wire. 5mm wire is 25A, 6mm wire is 50A. 50A is overkill, but that's what I bought! Picked up some 20A and 30A fuses, too. Obviously my 6mm wire will support a 30A fuse, but I'm not sure the existing wire's up to that standard...

Nick, you've been warned before, be careful what you offer! Might just take you up on that. I'll email later in the week when I know my schedule (looking after nieces and nephews, plus work) and you've got yours.

You've bought the wire so its too late but I purchased the next size up in the correct colours (blue with white and blue with red). Rated for 30 amp and only a short distance involved - forgot where I got it but was on-line and not expensive - Google is your friend

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

Well, it's done! I've had a pretty productive day today. I threw in the relays, changed the switch from the floor to the column, changed from sealed beams to H4's, and added a kill switch (which is in plain sight and looks factory - very pleased ). And it all works! Well, mostly...

First off, a few notes as to how I set it up. I used 6mm/50 Amp wire, with a 20A fuse on each side. I went with 20A as I figured that not all the wire was as robust or new as what I was adding. And I located the relays in the dash - before they go into the loom. This meant I had to run the two power lines from the solenoid back through the fire wall, but that was no real problem.

I have two problems, and a few observations. First, the observations. The new headlights I bought had Parkers inside them. I wanted to use them, as well as the parkers in the blinkers (roundie), but couldn't get the wires inside the buckets. I didn't really want to drill new holes... And I've got to look at my light switch - the headlights come on at the first click, along with the parkers, and the headlights turn off (with the parkers left on) at the second click. Finally, given all the talk about needing 5mm wire and big fuses, the wires through the bucket... They don't look like much more than 5A wire.

Now, my two problems. First, a pretty simple one. I've got to admit, I've never pulled a headlight before. I had real issues getting the (outer) covers off (old rubber buckets), and now I can't get the LH one back on. Any tips..?

Secondly... And this is a bigger one... My RH high beam doesn't work. I've tested, I've got 13.4V at the solenoid, and 12.3V at the light. That 12.3V is both from the Blue/White wire (High Beam power) to the body, and also to the earth wire (brown? It's pretty dirty - definitely not to the blue/red low beam wire). So, clearly, I've got voltage! The High Beam was definitely working before adding the relay. It stopped working on the RH side when the relay was fitted. I've used pretty well exactly the schematic Jacob/Vulcan posted above, both lights are illuminated by one wire taken off one side of the relay (post 87 only), then split up at the front of the car (I found the joiner). So I'm reasonably confident the problem isn't the way I've wired it.
One time, when I left the High Beam on slightly longer (i.e. not just on and off to see if it's working), the RH side did flicker on for a moment. I know that the RH Sealed Beam wasn't blown before the relays were installed. I know that the H4 wasn't blown when it was installed, and a visual inspection of the bulb says it's still not blown. I also tried the Sealed Beam from the LH side in the RH socket, again, no High Beam. So I don't believe that the Lamp/Bulb is the problem. And I've got good voltage at the connector. Where else should I look..?

P.S. - does anyone know why flicker, when not modified (italics, etc), triggers the swear filter like this - ******?

Sounds like a crook wire, with high beam on wriggle the wires a bit and see if the light reacts.
Volts can get through 1 strand of a wire when tested but when load (light) is applied you can get a high resistance causing problems.

My H4 conversions, i think i cut a notch in the inner bucket of the assembly to allow for the park light wires by memory.

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Dean Hutton's first car was a Mini.

I was thinking along those lines, Tombo... I'll go run another piece of wire, just as a test (with the light outside the bucket), and see how it goes... I'm thinking maybe the extra capacity of the switching is what's killed the wire...

You can always just try your old sealed beams in place as test units, sounds you have a dirty connection somewhere, remove and reconnect all connections and see how you go, oh and swap things around to isolate the problem.

Sounds like you're 95% of the way there!

Can you post a pic of the "rubber buckets"? Not sure I follow 100% what you mean there.

cheers

Jacob

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'72 Clubman Van - 1022cc, 295 head, 731 cam - Daily Driver
'69 Morris 1100 S - Dinged by a bus, in shed under repair
'64 Morris 1100 - Early 1100, long term project