Current Load Calculations - Much larger alternator needed

[ETI4K]

This looks like a great way to solve the space problem, but I would still need 3 more relay positions or find a way to drop 3 from the design. 

Bussman Series 15400 RFRM Rear-fed Fuse & Relay Module at waytekwire.com

124mm (4.88") x 235mm (9.25")

[AK260]

Sorry about not coming back with the measurements - totally slipped my mind, will do that this eve.

BTW, here’s a good video for you ...

[AK260]

Try these measurements ...

 

 

 

These is a 10-11cm wide space behind the blower motor but if you can go to the side of it there is plenty of clearance to the dash / glove compartment!

 

 

Bear in mind my car is RHD.

 

[ETI4K]

Wow, that's great.  Thank you for taking the time to post this.

 

I finally finished the wiring diagram for planned changes.  In the next few days I'll be bench testing some new control circuits, and if they work, I'll start modifying the harnesses.  These pics will help.

[AK260]

Most welcome.

 

Now then, this is potentially a small fly in the ointment! Since I started all this, I have changed my design to use the car’s existing loom (don’t boo quite yet) and keeps everything pretty simple. I am doing this job tomorrow, so I will report back!

 

This is a simplified diagram of how my car is wired as far as I can tell ...

 

 

Now, by a stroke of luck, there are Japanese bullet connectors that go from the stalk to the car’s wiring. One is white with red stripe and the other is fully red. I can’t recall which but one is hot, the other is 0v. So here’s the fun bit, by adding a single relay, you are effectively relaying the headlights through the car’s wiring by adding the diagram below into the blue circle by the headlight switch.

 

 

Now then no. 1 - I appreciate this contradicts my disdain for a single point of failure on both sides but frankly all you have done is replace the existing SPOF - being the stalk switch - by a more reliable relay. Heck you can carry one in your glove compartment as a spare and it costs pennies!

 

Now then no. 2 - the “rest of the car” side of the switch can be done the same way and entails just one more relay - but on my car I will have to cut the original loom or extract the terminals from the multi-plug and connect to them with a spade connector. Either way, it is a shed load better than a burnt out switch and keeps the wiring loom untouched.

 

Now then number 3 - I also hear you groan at using 40 year old wiring and connectors. Well, since I have LED headlamp bulbs the voltage drop across old wiring is frankly no longer an issue. The connectors from the wiring loom under the bonnet to the wiring through the wings to the lights need replacing or cleaning up anyway in my case.

 

Now then number 4 - let’s groan about the fuse box. One of my first jobs was to clean all connectors and fuse clips on the box and it has been flawless. With less current going through, it will be even less stressed. Oh and I’ve replaced the original headlight fuses with 5A ones now. Guess what, less current, less drop across the old wiring; win-win!

 

Finally, my tail, brake and reverse lamps are also LED replaced so that takes it from:

 

4x BA 15s @ 21w each to 3.6w each

 

2x BAY 15D @ 5W (constant part) each to 600mA each

 

This makes the old wiring and fuse box more than capable of handling the loads and no relay required for your brake lights. Another relay saved.

 

As for the indicators, you have two relays already - One is used for your hazards the other for your indicators. They are bi-metal strip based - just like your kettle (or mechanical voltage regulator) as the strip heats up, it bends away and breaks contact until it cools and reconnects.

 

My recommendation would be to change your indicator bulbs to LED and then change to motorbike flasher units which can take 10A and are rate adjustable to customise to your preference. That way for some pennies, you have now saved another relay slot. BTW some motorbike ones have a built in buzzer - depending on how loud your exhaust is that is either good or bad - make sure you get a silent one if bothered by a buzzer.

 

Something like this....

 

12V Speed Adjustable 2-Pin LED Flasher Relay Motorbike Turn Signal Indicator https://www.amazon.co.uk/dp/B01JRC5GZA/ref=cm_sw_r_cp_api_i_1rWWEbNSP831K

 

So lots of food for thought.

 

Ps. The diode in my circuit diagram above is optional, but if you consider that an inductor (I.e. the coil in your relay) will always try to keep the current flowing in the same direction, once disconnected, it switches it’s voltage at the terminals instantly and violently which can reach 100s to 1000s of volts depending on the coil size. This is low current, but the spike can cause issues with sensitive circuitry if you have other things in the car like an AFR gauge etc. It’s basically belts and braces precautions.

 

 

 

 

 

 

 

 

 

 

 

[Captain Obvious]

3 hours ago, AK260 said:

This is a simplified diagram of how my car is wired as far as I can tell ...

The US cars don't have the flash button, so I'm operating without a net, but your diagram does not look right to me.

In the US, the headlight fuses are not hot at all times as you have shown. The OFF-ON switch is between the battery and the fuse box. The fuses are only hot when the headlights are turned on. In addition to that, with what you have drawn, the ONLY way to get the high beams to light up is to push the flash button.

I think there's stuff wrong...

The newest thing I have here is the 72 manual still shows the FLASH relay, and the basic system is pretty much the same as the US with the exception that the flash relay is wired in parallel with the rest of the system and will turn on the high beams even when the headlights are not on.

Would it help if I were to sketch up the 72 system?

[AK260]

The US cars don't have the flash button, so I'm operating without a net, but your diagram does not look right to me. In the US, the headlight fuses are not hot at all times as you have shown. The OFF-ON switch is between the battery and the fuse box. The fuses are only hot when the headlights are turned on. In addition to that, with what you have drawn, the ONLY way to get the high beams to light up is to push the flash button.

I think there's stuff wrong...

The newest thing I have here is the 72 manual still shows the FLASH relay, and the basic system is pretty much the same as the US with the exception that the flash relay is wired in parallel with the rest of the system and will turn on the high beams even when the headlights are not on.

Would it help if I were to sketch up the 72 system?

 

 

 

Yes please, always up for learning. I did think the HB side was wrong when I went to bed eventually!

 

I do realise the ignition switch does turn off the power but I was also simplifying the diagram to demonstrate the new relay position. But I appreciate that does cause confusion.

 

Would love to see that sketch on the HB side though please.

 

So if you guys don’t have that button, how to you flash your lights? Or do you just go without?

 

Strangely a quick flash in the UK means “come on, after you and thank you”. Or if behind Someone it means “get off MY road”!!!!! I confused the heck out of the French when driving on the continent, as for them it means “don’t even think about it, I’m coming through or you utter moron”. For us, that is holding the flash button down for more than half a second.

 

In Mumbai in India, I realised that a flash means “I’m here, see me, I don’t care that there are cars in front of you or you have nowhere to go, get off the planet, I’m here now”! The horn serves much the same function during the day as many cars had their wing mirrors folded in to - get this - avoid having them knocked off while driving! [emoji1787]

 

 

 

[Captain Obvious]

11 hours ago, AK260 said:

Would love to see that sketch on the HB side though please.

Here's what the 72 system (with the FLASH feature) looks like. Other than the addition of the FLASH / PASS button and the passing relay, it's pretty much the same thing they used in my 77. Point being.... I'm assuming that all the years in between are also the same, including yours.

You can see that the pair of headlight fuses are not hot at all times, but are only hot when the headlights are turned on. You can also see that the headlight system has no interaction with the ignition switch at all, so the headlights can be turned on regardless of the key position. Same thing goes for the FLASH system.

Also interesting to note that when you push the FLASH button, it will turn on the high beam filaments. Full stop. Doesn't matter if the headlight switch is on or not. Doesn't matter if the lights are already on in LO beam. Even if the low beams are already on, it will power both filaments at the same time while the FLASH button is being pressed.

Hand drawn in all it's glory:

Hope that helps!

 

Edited May 19, 2020 by Captain Obvious

[AK260]

CO, if you weren’t so far away and socially distanced I may have given you a hug! A man hug I may add. Very un-British I know but none-the-less a hug!

 

So you got me to doubt myself and I measured it this eve, you are absolutely right, the ignition switch has nothing to do with it! I eat my own words - my light wiring is hot all the time!!

 

 

Thanks again for taking the time to draw that out! I never do well with car wiring diagrams. [emoji106][emoji106]

 

Edit: why is frightening about that diagram is the lack of a fuse before the headlight stalk. So I’m effect, you can quite easily have a car-b-q if the wire is somehow damaged and grounded before the stalk! [emoji848][emoji33]

[Zed Head]

The switches on top of the steering column are known for broken solder joints and pitting.  You can add a relay in various places along the path.  Pry the top off of your switch and you might be shocked at what's going on in there.

Rabbit hole...

[wheee!]

Part of the reason that I added relays today...

 

[madkaw]

3 hours ago, Zed Head said:

The switches on top of the steering column are known for broken solder joints and pitting.  You can add a relay in various places along the path.  Pry the top off of your switch and you might be shocked at what's going on in there.

Rabbit hole...

Someone could make a fortune with their 3D printer and make that high beam switch on the column . It’s the part that fails the most . It’s the reason to do relays . Repairing them is tricky , not much to solder too.