Complete idiot moment tonight. Battery mounted wrong way! HELP!!!

[JackDaniels73]

No other explanation than complete brain failure after sorting out frunk. School boy error and managed to terminate battery wrong way around.

Result was as expected. Pop and bang from + inline fuse and a click or two from what I think was passenger side. Disconnected all pretty quickly, but obviously car now dead......followed up with a large number of self deprecating swear words.

Aside from banning myself from working with anything more complex than Lego going forward, what needs to be checked? How do I fix my dump ass screw up?

Guess I start with in line fuse, but how do I check/fix that?

[JackDaniels73]

In-line fuse all good. Looks like the 120a fuse has blown. Replace tomorrow and keep fingers crossed it did not fry anything else.

[pistol pete]

sounds like you are going in the right direction, replace that fuse, cheal ALL fuses just to be sure

don't stop working on cars because you done something wrong, we have all done something that we will never do again!!

[Marf]

I did exactly the same on my Charade Turbo years ago, it blew the main fuse which saved the rest of the electrics. Replaced the main fuse and everything was golden again

[JackDaniels73]

Thanks for the encouragement chaps.

Took a few days longer than I expected to get hold of a 120a. But pleased to report all is good now fuse is in. Will run full checks tomorrow to be 100% sure.

Complete FAIL seems to have been avoided.. Phew . Total idiot moment and one I will not repeat in a hurry.

Will stick with it. In fact I'm a few month in so will try to blog my progress soon!

[Willenium]

I did this back in July last year. After consulting the Google bank of knowledge I ended up stripping down the fusebox to find that everything was fine in there. Luckily a chap on here informed me of a hidden fusible link which it turned out was the culprit.

Nice when the panic is over isn't it

[JackDaniels73]

For sure. Especially when the leccy bit is where I'm least confident right now.
With each mistake my knowledge is getting there. Definitely got away with it this time....

Still scared to have a go at putting in the Battery cutoff as I know you need to isolate the alternator and the battery, otherwise bad things will happen.

Scouring the posts for some clear instructions before I even go near it. The switch came with next to F'all guidance.

[ashley]

What isolator have you got? Are you planning on competing, and do you need to comply with motorsport reg's?

Different ways to kill the alternator, and different requirements for how you isolate the battery depending on what you need to do. All pretty straight forwards though

After a lot of research, and some help, I've gone total overkill



They take an interesting approach though- this one isolates the battery negative from the chassis earth point, and outputs a "kill" signal that goes to my PDM to tell it to kill the alternator

[JackDaniels73]

No intention to race at this stage for sure, but I am preparing it for track use and wanted to apply good sense safety preparations. Thought a cutoff made a lot of sense to put in place for a few reasons.

I bought one that stated it is made to FIA spec. Part is K-596, but suspect that adds little to no value

To describe the main switch. It has two main connectors, M8 bolt size by the looks of it, plus 4 additional male spade connections at base of switch (Two marked '1' and other two marked '2') also came along with a separate 3 OHM 11 Watt resistor.

Instructions is a basic image of the switch telling me what to connect to it, where I need some guidance is where on the car to best pick those up from safely?

Battery + : Left M8 connector
Main Electrical Feed circuit : Right M8 connector.
Main Electrical Feed circuit : '1' Right spade connector.
3 OHM 11 WATT resistor : '1' Left spade connector. (easy one )
Ignition coil : '2' Left spade connector.
Ignition switch : '2' Right spade connector.

Hope that helps and appreciate any guidance, to avoid ground hog day with the 120a fuse or worse!

[ashley]

Let me dig out some wiring diagrams when I get home and I'll report back mate

[JackDaniels73]

Awesome. Thanks!!!

[ashley]

Sorry- totally forgot about this

I'm guessing your diagram looks something like this?



Seems fairly straight forwards:

You connect the large poles between battery positive and and the main +'ve car harness; this circuit is normally closed, and so the car electrics have a +'ve feed.

You then need to cut the ignition/ switched live feed to the coil and reconnect this across the two "2" poles. This circuit is normally closed, and so the coil will have +'ve feed for ignition.

You then run a wire from the main +'ve car harness to one of the "1" poles, and the other "1" pole connects to the resistor, and the other side of the resistor you connect to earth. This circuit is normally open, and so the resistor is not connected.

When you activate the cut off switch it breaks the main +'ve feed to the car electrics. It also breaks the +'ve feed to the coil, and so cuts ignition and in turns prevents the engine running on (powered by the alternator).
Finally this also grounds the main +'ve car harness across the resistor, presumably to prevent any large voltage spikes from damaging other components (I'm guessing on that score!).

I imagine that the resistor will get quite warm when you use the cut off switch (at least for a little while), so probably an idea to mount it away from other components and wires.

That's my best take on it anyway, if I was you I would double check with someone who has wired one in before to be sure, the last thing you want to do is have a switch that doesn't actually cut off when you need it most

[JackDaniels73]

Very helpful. thanks for taking the time and having a go at getting me further.

You nailed the image, pretty much a match, although mine has no labels or anything, so that alone is helpful.

When you say Battery Positive, Mine has two wires on the +ve, one being the in line fuse (blue). Do you leave the in line fuse connected directly to the battery and just divert the main +ve via the switch or re-route both?

Welcome feedback from any other members as suggested before I think of getting the wire cutter out .