Fuse protection

[nalle]

If I have understod right, there are no fuse protection between alternator and dashboard.
So all the fuses are after switches, light etc.
If it is so then, I do not like it.
Have anybody added a fuse between alternator and dashboard (in the brown wire)
If so, what was the size of the fuse.
Propably 30A-50A is enough (it will still burn if there is a short in 1,5mm2 wire)?
And is the fuse installed in the engine bay or uder the dashboard.

[azruss]

The only need for a fuse in the brown wire would be if you got a short in the brown wire. Any fuse big enough would provide no protection for any of the other circuits in the car. Any short circuit in that wire would instantly burn a hole in the wire and break the connection.

[nalle]

Yes you are right the brown wire will be burned by battery power, question is will the burning end in that wire.
The brown wire short is the worst case scenario (4mm2 carries normally 20A and special cases 46 A, without overheating).
If battery gives 600 A it will not burn instantly, it takes few seconds.
Smaller wires burns easier.
And the "burn" is something what I do not want (except fuse burn).

I do not agree that "The only need for a fuse in the brown wire would be if you got a short in the brown wire"
If I read wire diagrams right there if no fuse before ignition swich and no fuse before light swich.
There shoud be.
All open / close contacts are always possible failure places (Ignition swich, light swich, also loose abico connectors etc)
I have seen what happens when you make a short in dc-circuit.
If you have a good insurance you get a new car, with bad insurance you get blue mind.
DC will not die easily and battery has the power to keep flame on.

It's quite easy to check needed fuse size, just measuring the max. curent in the brown wire and muliply it by 1,5 or somehing like that and then choose fuse.
I just wondered if somebody have better idea to do the protection or somebody have already done it. (I was lazy).

Other possibiliyty is to build a battery main fuse, but that have to be so big and difficult to estmate the right fuse value (audi do it this way atleast in old A3).

Maybe I'm over reacting but I like my car (and do not like unprotected ciruits).

[azruss]

Since so much power goes through the key, i relayed the entire car. built a fused relay box and put it under the front cowl. I spliced in so there was no change in the factory wiring to the key, so it could be removed and taken back to original.




As I recall, I blew one fuse right away and had to go one side up. I think it was the ignition circuit, but not sure.
Feel free to use this if you think it does what you want.

[nalle]

Nice work you have done.
This is exactly what I want to do (or you have done even more).
You have even found a nice relay box.
You did all your modifications after the C17 connector.
Where did the box fit in your car, do you have any picture of that.

My plans are that I will put a fuse next to to engine (some where under the hood).
Then I will make a realy system for starter coil (solenoid) (also Fused )and for the head lamps (using orginal fuses).

My main points are :
1. reduse current what flows through the Ignition swich
2. Fuse protect all electrial equipments (ex. battery main wire)

Thank you for the picture.

[vandor]

I know many Japanese cars have a 'main fuse', so it's not an uncommon practice.

[spider2081]

I believe on most of the spiders there are 2 #10 unfused wires that are fed directly from the battery. One of them is from the alternator output terminal that connects to fuse 10. The other is from the starter solenoid that connects to C17. On FI spiders there is also a brown wire molded into the battery positive connector making a total of 3 wires not fused at their source.
There is also a #8 wire that connects the alternator to the starter solenoid on the battery post that is not fused.

Some modern cars use fuseable links to protect circuits similar to the Fiat #10 wire circuits. Some others use self resetting circuit breakers in these circuits. I don't think any protect the connection between the alternator output and the battery.

[baltobernie]

I know many Japanese cars have a 'main fuse', so it's not an uncommon practice.

Yep. It protects the entire fuse block.

[nalle]

ok mow I have got a little understanding of what I'm going to do.

Brown wire will get a MIDI fuse, 30A?? the current has to be measured first, at the moment it is not possible.
MIDI fuses charasterics are "slow" enought for a main fuse.
Front light are going to have relays I'll use original fuses for lights ( very simple connection).
I'm not going to get brighter lights, just reduce Ignition swich current.

Also the starter solenoid current has to be measured => fuse + relay.

In the matter of fact it is not rare to have fuse between alternator and battery (fuse protects alternator), but it's rare to have fuse between battery and starter (it might be possible if you choose slow fuse). I have to check it.


Then one question:
Does spider normally has automatic lights (= motor starts and ligt will go on, motor stops and lights will go off)?
At the moment in my spider has automatic lights, but is has been done a really strange / wrong way => too warm wires

[baltobernie]

Does spider normally has automatic lights (= motor starts and light will go on, motor stops and lights will go off)?
At the moment in my spider has automatic lights, but is has been done a really strange / wrong way => too warm wires

None of the Spiders sold in the USA had automatic headlamps. Perhaps Finland, like Canada and others, requires Daylight Running Lamps, and a previous owner attempted such a modification on your car.

Your first step is to determine how your car's wiring was modified to achieve DRL status. Look for obvious signs, such as wire colors, sizes and construction that are dissimilar to the OE Fiat wiring. I suspect that you have some current flowing backwards, with two circuits On at the same time. Do a Search for a wiring diagram for your model year. You'll notice that the headlamp circuit is not at all straightforward. I'd think that the proper way to add DRL to the Spider would involve diodes and relays to separate the two functions. The safest way would be to remove the PO modifications and add auxiliary lamps to satisfy this requirement, if your motor vehicle laws require it.

Perhaps one of our northern members would like to chime in here.

[majicwrench]

My 72 Spider, with the headlight switch in the up position, will turn the headlight on when you start the car, and off when you shut it off. Automatic headlights.
I have fuseable links protecting system. GM at the least has fuseable links tween battery and alternator.

Adding relays......I applaud folks for wanting to protect their system, but really, relays can, and do, fail. So do connections fail. So by adding relays, you have added a BUNCH of new items and connections to fail.
Simple is always better, and less is more.
Hack away if that is what turns your key.

[baltobernie]

I stand corrected.

[v6spider]

In my 1972 spider the lights are driven from battery power and do not turn off when you turn off the key.. Just as every other car I am familiar with from that era..


Rob

[spider2081]

Automatic headlights.
I assume you are talking about your 1982 Spider 2000.
I have a 1981 Spider and the wire diagrams for 81 and 82 are the same for United States cars.
There is one power switch to turn on the parking lights and the head lights. When the batt of the switch is up both parking lights and head lights are off regardless of the ignition switch position.
With the light switch in the middle position the parking lights are on regardless of the ignition switch position. Parking lights are powered from the cars "hot all the time circuit" when the ignition switch is in the off position.
With the light switch in the full down position the headlights and parking lights are powered on through the ignition switches "hot in start and run" positions.
It is not whether the engine is running but the position the ignition switch is set.

Even with our 2012 500 wiper power switch up is off and down is on

[nalle]

Thank you for you answers.
Reason why I started to wonder the wires was one too warm wire.
Then I mesured the currents:
"Brown" wire 0,3-0,5A, Shoud be 10-20A (depending on light swich position)
The other wire (do not remeber the color, propably black near ignition sw.) 23,5A.

Anyway you are right I have to check the diagrams.
But battery is not connected at the moment and it is easier to do testing with online system, than offline with resitance meter.

About relays, I agree that relays are one possible fault position more, but I have used to work with good relays and I belive on them more than swiches (swiches are made for control and relays are made for power).