Check your electrical routing, What can happen when it all goes wrong on track.

So Greg Amy posted this video from his E production 8th gen Civic at runoffs last week. 

Gets about 3/4 of a lap into his race and then an O ring gives out on a fitting for the oil cooler and car looses oil underneath onto the header, smoke enters the car and goes off track, fire then commences under the hood. 

Big part of this video is the recurring fires under the dash with the safety crew there trying to secure the vehicle to get it off course. A wire from the battery positive melted down and was grounding on the chassis and shorting and causing new fires. Something to think about if you're building a racecar with custom wiring. 

That's nuts. And probably not something people put enough thought into 

So how do you prevent this, other than a really big fuse right at the battery?

I've used ANL fuse and holder for this near the battery, as codrus suggests. Easy to size compared to fusible links OEMs etc use.

Equally troubling is the fact that his HANS device seems to get snagged on something as he's trying to bail out. Not sure what the solution to that would be.

codrus said:

So how do you prevent this, other than a really big fuse right at the battery?

 

Battery shutoff switch.

That is one advantage of an in cabin battery, you can mount the switch where you can get to it, and keep the run from the battery to the switch short and away from the usual potential fire hazards.  And if you route the alternator output to the battery side of the switch, the switch becomes an instant kill switch.

In reply to Woody :

They will do that sometimes if you don't flip the harnesses all the way off your shoulders. I'm not sure if there is a good solution for that with certain belts. What's concerning for me is trying to get out of a halo seat, with a HANS on when you can't open the door. Especially in cars with a right side net. Low probability event that keeps me awake at night when thinking of building a race car. 

Knurled. said:  And if you route the alternator output to the battery side of the switch, the switch becomes an instant kill switch.

Wouldn't that leave you with a heavy gauge wire that is hot all the time, not controlled by the switch, and not easily routed away from hazards?

Knurled. said:

codrus said:

So how do you prevent this, other than a really big fuse right at the battery?

 

Battery shutoff switch.

 

That is one advantage of an in cabin battery, you can mount the switch where you can get to it, and keep the run from the battery to the switch short and away from the usual potential fire hazards.  And if you route the alternator output to the battery side of the switch, the switch becomes an instant kill switch.

And one should also repeat that the wiring of said cut off switch changes if you have an alternator or not.  One must make sure that the switch will cut the entire car off of power with one event.

It's also important to note that this car turns out to be an illustration of why some kind of fuse/breaker system is needed for cars that do not run alternators.  Way, way back, on the Alfabb, there was a discussion about this- where it was concluded that you need fuses/breakers if you have an alternator, but don't if you don't.  This pretty much shows the need for breakers/fuses, regardless of the system.   Racecars have super simplified harnesses, so even if you bought the best of the best airplane switchable breakers, it's not going to break the bank.  But having them will surely save a lot of potential damage.

gearheadmb said:

Knurled. said:  And if you route the alternator output to the battery side of the switch, the switch becomes an instant kill switch.

Wouldn't that leave you with a heavy gauge wire that is hot all the time, not controlled by the switch, and not easily routed away from hazards?

Two things- the wire from the alternator isn't that large- it does not output anywhere near the battery does when starting the engine; and once you isolate the battery, then the field charge for the alternator goes away, and it can not make power.  The wiring for the alternator only supplies the battery, so once the battery is isolated, you are done, power wise.  IIRC, there are special cut off switches for alternator applications....

As for the routing- the power has to go someplace- so if you can't safely route it to the battery (where ever it is), how can you safely route any of it?

Wow, what a mess.  Between oil, burnt stuff and fire media that won't be a fun cleanup. 

gearheadmb said:

Knurled. said:  And if you route the alternator output to the battery side of the switch, the switch becomes an instant kill switch.

Wouldn't that leave you with a heavy gauge wire that is hot all the time, not controlled by the switch, and not easily routed away from hazards?

If the alternator feeds the car side of the switch, the engine will stay running off of the alternator.

Run the alternator to the battery side, hitting the switch WILL shut down everything like President Madagascar.

The one that I'm waiting for is when a big fire happens with an electric or hybrid vehicle at the track and the batteries go into runaway.

I have seen reports where roadways were shut down for 6+ hours when an electric vehicle simply wouldnt stay extinguished so it could be removed. It will be interesting to see how tracks deal with EV's as they become more prevalant. 

Knurled. said:

 And if you route the alternator output to the battery side of the switch, the switch becomes an instant kill switch.

As an aside -- If you do this on any semi-modern car, make sure to put a big ass resistor between the alternator output and ground when the switch is in off position so that you prevent any voltage spikes from the alternator upon sudden shutdown.  This is must for normal kill switches too.  

On our Fiesta we run the stock push button start and reserve the kill switch for tech inspections and emergencies.  Kill switches make me pucker every time with all those computers on board.  Half the time after the kill switch is used, we get "Key Not Found" error and have to do a voodoo dance to get it going...usually only during pit stops.

In reply to Apexcarver :

I've read in Belgium this solution has been used, take one open topped shipping container and place EV in container, fill container with water, and simmer for 48 hours and check EV for doneness.

Maybe route oil lines so they can't spray oil onto the headers? 

How about putting the cut off switch on the negative cable from the battery?

ChasH said:

Maybe route oil lines so they can't spray oil onto the headers? 

How about putting the cut off switch on the negative cable from the battery?

Ding ding!  Thats the winner - My car has a 4 pole switch. The big lugs open the ground wire from the battery, the small lugs open the alternator to harness power.  Opening the switch kills alternator output and battery ground.  It was frustrating before I realized how it was wired - I had NO +12V anywhere (referenced to the chassis).

Also you cant post the original version without showing the Jackie Stewart version:

Kendall got it right..... a 4-pole switch works best. That's what I used on my race cars and I thought that was an SCCA requirement.

Possibly something like this would help mounted right at the battery inline.

https://www.amazon.com/Circuit-Breaker-Cover-Reset-Battery/dp/B07H8BZLVY

We ran a 4 pole switch in our chump car.. ran the battery positive through one side and key ignition ("engine on") through the other. Is there a reason that's a bad idea? Flip the switch and the battery gets cut, ECU stops the engine. Engine can't still run off the alternator if the ECU shuts it off? It was much more convenient than running the alternator wiring back into the cabin.

Apexcarver said:

The one that I'm waiting for is when a big fire happens with an electric or hybrid vehicle at the track and the batteries go into runaway.

https://www.youtube.com/embed/AQVzW63ZWxc?rel=0

 

https://www.youtube.com/embed/-7lHjzL9QYM?rel=0

 

 

I have seen reports where roadways were shut down for 6+ hours when an electric vehicle simply wouldnt stay extinguished so it could be removed. It will be interesting to see how tracks deal with EV's as they become more prevalant. 

EV fires don't stay extinguished because it's an exothermic reaction that occurs when the cells are damaged. All the energy stored in that battery has to go somewhere, and it comes out via heat when the batteries are damaged. It will keep coming out until the energy is gone - thus everything continues to catch on fire, and you have to keep dousing it with water to carry the heat away. 

The key on Greegamees fire was that it was BETWEEN the battery and cutoff switch.  The oil fire had burned the insulation off the wire and it was just battery straight to ground.  I think 99% of SCCA cars are wired this way - they cut the batt positive and alternator.  For the most part it works, except for when it doesnt.

Putting a breaker or fuse in there may work - but also adds some complexity and reliability issues.  Fuse may pop when you start the car, then your a DNS.  Circuit breaker may not trip fast enough & may not like being in the high vibration / hot race car.

Cutting the batt ground and alternator hot wires seems to be the easiest solution but I'd like to hear what others are doing. 

Also <PRO TIP>, you should never ever use your master switch to shut off the car - only use it for tech inspections or emergencies.  These are high current mechanical switches - you know when you connect jumper cables to a chassis and see the spark?  Thats whats happening in that switch.  Do it enough times and there is arc damage & carbon buildup. In the ohms law world high current and low voltage is really susceptible to small resistance changes -  and people get bit by that all the time "when the switch craps out".  Switch the master switch off last when nothing is running.

I am not sure why anyone worries about the alternator, stop the engine and it stops charging. 

Considering there is no way to “discharge the battery and alternator” per scca rules it just needs to be isolated (would be cute if they learned English, or electricity) as that is the intent  

It is unfortunate a dual failure happened but after a massive engine fire I wouldn’t give two hoots about the issue of the battery wire fires. Should be easy enough to put out when the main fuel from the fire (fuel, oil) is cleared out.

 These are high current mechanical switches - you know when you connect jumper cables to a chassis and see the spark?  Thats whats happening in that switch.  Do it enough times and there is arc damage & carbon buildup.

In high voltage battery packs on hybrids and EVs there are contactors (relays) that connect in stages to manage this arcing problem.  In theory a good switch should be able to take it just as often as a starter solenoid does (i.e. every single time you use the car for years and years) but reality is something different since these switch manufacturers arent selling to OEMs, what with their 'standards' and 'requirements' and other fuddy duddy stuff. 

I think a lot of people building cars know someone or know someone who knows someone who can measure starting current. Get that number, get a fuse maybe 100a over that, and be done with it. Even with a huge fudge factor that fuse will still blow if you short the battery positive directly to ground.  My .02.

So, when I relocated the battery to the  trunk on the Intrepid, I added a cut of switch (NHRA rule, mandatory for any vehicle with a relocated battery, accessible from the exterior of the car) and added a heavy duty fuse (125amp rating I believe) in line from the positive post to the battery.

Other than a bit of routing, it added no real complexity to the setup, and I mounted the fuse holder in an easy access location in the trunk. I treated the car like a car and I have never had an issue with it. I carry a spare fuse with me in the extras bit / special tools container for my car.  I was even complimented on it by the NHRA tech inspector when I took it racing as he hadn't seen that before on any of the dedicated drag cars he has seen. 

I guess the other up side to the fuse is IF the battery cable gets damaged in an accident it 'could' potentially blow the fuse before someone gets close enough to throw the switch.