Landracing Forum
Bonneville Salt Flats Discussion => SCTA Rule Questions => Topic started by: ronnieroadster on February 04, 2015, 09:44:13 PM
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When I read the rule for batteries it says a main disconnect switch on the positive lead of the battery.
Knowing the main battery controls the engine and fuel delivery system the kill switch disrupts power to the engine and fuel. If there's another small sealed battery only used for data or an air pump must that also be connected to a disconnect switch?
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Miss Liberty has a secondary battery for data logging, its ground cable has a solenoid in it with its own switch on the switch bar out side of the master switch. The battery disconnect at the back of the car also kills the power from the secondary by depowering the solenoid.
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Mine has a big switch that turns off the battery positive 12V. It is actuated by a push- pull control cable in the nose of the car.
I also have a big relay that shuts off all 12V power if the impact switch is triggered or the guarded toggle switch on the panel is flipped.
Regards, Neil Tucson, AZ
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Good question Ronnie. I'm anxious to hear the answer. :wink: Keeping both of those things operable could be quite handy. Wayno
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As I recall, the main switch is to shut down motor and fuel feed in case of a roll cage test session.
Your data and vent fan should be OK on separate power.
As always, the opinions posted here are just an opinion worth less than or equal to what you paid for it.
John
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As I recall, the main switch is to shut down motor and fuel feed in case of a roll cage test session.
Your data and vent fan should be OK on separate power.
As always, the opinions posted here are just an opinion worth less than or equal to what you paid for it.
John
You might be right but I'd think you are trying to cut off all electrical to avoid possible sparks from any battery. We run the solenoid to cut off the data battery.
We and others should also think about doing what is required in boats and that is have a fuse on any battery within 6 inches of the battery which should also kill the battery with a short although a short on a small wire could still burn the wire up and not blow the fuse.
I use these....
(http://www.genuinedealz.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/B/l/Blue_Sea_Systems_5191_5_1.jpg)
(http://www.genuinedealz.com/media/catalog/product/cache/1/small_image/160x160/9df78eab33525d08d6e5fb8d27136e95/B/l/Blue_Sea_Systems_2151_12.jpg)
...now and will also use them on the lakester. They mount right on the battery and .....
(http://www.genuinedealz.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/B/l/Blue_Sea_MRBF_Terminal_Fuse_194.jpg)
.... you can buy fuses in different sizes. Not that much money and they could kill the power in a major accident well before help got to the car maybe preventing a fire. I've gotten them from here...
http://www.genuinedealz.com/marine-electrical-supply/fuses-and-blocks
Sumner
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Speaking as an ex inspector, here is my take;
The battery disconnect switch is not a kill switch, it is used to remove all electrical power so the first responders do not have to worry about causing sparks when extricating the driver from the vehicle. Our modified roadster has a 12 V alarm battery used to power the tach, it has a disconnect switch.
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Speaking as an ex inspector, here is my take;
The battery disconnect switch is not a kill switch, it is used to remove all electrical power so the first responders do not have to worry about causing sparks when extricating the driver from the vehicle. Our modified roadster has a 12 V alarm battery used to power the tach, it has a disconnect switch.
The book doesn't state an objective, it merely says to have a disconnect means and where to locate it. Also, it does not state which side of battery to switch.
I would argue that killing the motor and potential fuel leakage is more important, but likely will not satisfy anyone here.
In other sanctions of racing, the tech inspection of the "battery disconnect switch" is to kill the motor and make sure it overrides the alternator.
John
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Which side of the battery should be opened by the disconnect switch? The NON-grounded one, whether positive or negative. If the hot side is not disconnected the entire vehicle will be energized to the battery's voltage, and therefore a piece of metal that falls across the ungrounded battery terminal/cable will conduct, and that's not a nice thing to do to safety workers.
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Jon;
If you break the battery ground connection the positive 12V lines can be shorted to ground without causing a problem because the current path back to the battery negative terminal is open. Theoretically, either the - or + battery connection can be broken by a switch; most builders prefer the + (positive) conductor but that's only due to convention.
Regards, Neil Tucson, AZ
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What do you recommend for KAP (keep alive power) to your vehicle's computer?
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Neil said: "...Theoretically, either the - or + battery connection can be broken by a switch; most builders prefer the + (positive) conductor but that's only due to convention."
I was careful to leave "positive" and "negative" out of my comments -- because there were and probably still are those that ground the hot side of the battery. Whatever -- sure, there's gotta be a completed circuit for them there little electron-thingies to meander upon to make stuff work -- stuff like the cigarette lighter and the big-a** spark generator and that kinda stuff.
ZAP!!
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What do you recommend for KAP (keep alive power) to your vehicle's computer?
Just an observation. If the master kill switch has to be used, probably the retention of data is the least of your worries. If you've got time before you want to use the master kill switch you can probably attach a supplementary power source for the computer before you shut down the main system. I'm of course ignoring the fact that the data could be used for accident investigation but then it should be on some sort of recording and storage system.
Pete
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Peter,
You are right about the retention of data, however, in some systems power is required to retain the data.
It doesn't take much, small battery is used.
J
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http://www.landracing.com/forum/index.php/topic,1331.0.html (http://www.landracing.com/forum/index.php/topic,1331.0.html)
Mike
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On the Salt Cat ll car we have two shutoffs in series. The one that is in reach of the driver kills all power except to the computer for the datalog, and the helmet fan. The main disconnect at the rear kills all power. If it gets to that point, I won't need the data from that run anyhow.
Doug :cheers: :cheers: :cheers:
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One action should make the car completely dead. If you hit the main kill and can still hear the whirring of a fan going some where then I'd say you'd be a no-go in tech. IMO perm power to a logger or ECU isn't a concern so long as it's only power to maintain memory and isn't actually used to power coils or injectors or anything else.
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Nathan, my car isn't done but there's a main switch in the cockpit and one each at the front and back for rescue.
If either are activated it cuts off everything and the main in the cockpit needs to be set to "on" manually after activation.
Is this the right system?.
Thanks, Mike. :cheers:
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One action should make the car completely dead. If you hit the main kill and can still hear the whirring of a fan going some where then I'd say you'd be a no-go in tech. IMO perm power to a logger or ECU isn't a concern so long as it's only power to maintain memory and isn't actually used to power coils or injectors or anything else.
Nate is it not a ruling to avoid any hot wires in the car that could possibly spark and ignite fuel not just those that are required to run the engine?
I could see where someone has an incident and the car is on its side and the power is off so the engine can't run but while turning the car over or possibly having to cut it open to get to the driver a wire going to the data recorder or ECU was cut or a damaged wire to it contacted ground and caused a spark and there was fuel you could have a problem well after the initial accident.
Sumner
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I was "told" that no hot wires was the objective of the battery cut off it was to function as a MASTER KILL SWITCH for all power.
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You can theorize it however you want. I've not yet witnessed a fire that was started due to a spark from a damaged 22 gauge wire that's keeping your logger memory. That sounds a lot like the rule change scenario Chris described with his wreck leaving broken headlight glass on the course. I have been on scene at a fire that couldn't be put out because a fuel pump was still running and pouring fuel on a hot not running engine because the main kill couldn't be found and the driver was unconscious... oh and the car was upside down. Getting that front or rear kill switch location rule through really made a lot of sense.
If a wreck is bad enough that someone is getting cut out of it, the battery is probably long gone having been flung a quarter mile from the accident epicenter. If the rule was to prevent any hot wires from arching against the chassis wouldn't the rule require that you cut off the ground side of the battery? Anyways, I think getting engines and fuel pumps turned off is a bigger concern that sparks. A hot engine is a lot more likely to ignite a fire than a stray spark.
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Nathan;
A cut-off switch in either side of the battery will work. It doesn't matter if it is in the positive or negative side of the battery-- the key is that the circuit is broken so no current can flow.
Regards, Neil Tucson, AZ
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Not to mention the battery should stay in its place if it is installed according to the rules. In my little incident, the back of the car broke off, and the cutoff switch was no longer attached, although it did manage to turn itself off before the wires were ripped loose. The battery stayed in its location until I put it in the truck when one of its batteries went south.
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:cheers:
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The intent is to kill power so engine and fuel delivery is dead during an emergency that's no problem. Example being the main battery feeding engine/fuel is located in the rear of vehicle and battery kill is located in the rear also. Main feed wires from this battery are then short in length with battery location to kill switch. Potential for problem developing from this battery is lessened by the shorter cables. Second battery is located in the front of vehicle to help with center of balance this battery is not used to feed any engine functions. If the wiring from this second battery is run the length of the vehicle to the kill switch location the potential for a short due to a crash has not been eliminated the additional length of the battery feed wires have now been run the length of the vehicle and back to the battery located up front adding to the potential of an issue due to these longer wires one of which will always have a feed on it. Using a relay to open the feed wire from the front battery seems to be the answer. BUT it has to be located at the battery to be of any value if that's truly what the rule imply's
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Nothing says you can't run two switches - one for the front and one for the rear BUT they should both be able to be activated simultaneously from one location. Most are achieving this using cables but I'm sure there are many ways to skin this cat.
Stainless I'm surprised to hear that your battery was intact after your wreck. I did not see the extent of your accident although I heard it was pretty bad and that you were lucky to have gotten away with what you did, but, the majority of accidents I've responded to have the batteries launched very far from where the car winds up.
Shorts, sparks, and shocks are all good concern but I think a higher priority is getting engines and fuel pumps shut down.
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My take is that it is so easy to put a cut-off relay, costing a few bucks, at the data logging battery why not do it? Then you have your bases covered,
Sumner
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My battery is located in front of engine and under the fuel tank. The electric fuel pump is right beside it. The cut off switch is on a side hood panel 6" from the front and VERY visually marked.
Sounds like I did everything wrong......but follow the rule book.....
Anyone know where the battery disconnect is on a NASCAR? I don't believe it's in the rear....JD
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My battery is located in front of engine and under the fuel tank. The electric fuel pump is right beside it. The cut off switch is on a side hood panel 6" from the front and VERY visually marked.
Sounds like I did everything wrong......but follow the rule book.....
Anyone know where the battery disconnect is on a NASCAR? I don't believe it's in the rear....JD
Watched the Daytona Race noticed the battery disconect was on the drivers dash.
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Ronnie... Makes perfect sense since now NASCAR now uses an electric pump. (Dah inside the car) I know it means nothing to our style of motorsports but NASCAR doesn't have a shut off like we need either. I personally think the shut off we first used for an electric pump that was tied to the oil pressure of the engine was a better idea.....oh well
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After a lot of thought and research I think I have a solution on how to turn off the secondary power from the remote battery in the front of the car. The main battery being located in the rear of the car is connected to the battery kill switch. Using a relay I found at Radio Shack and also under the hoods of most new cars I can wire the secondary feed wires through the high amp contacts in the relay.
Connecting the pickup coil wires from this new relay to the feed buss from the primary battery will now energize the relay. This will allow the high amp contacts in the relay to close the circuit so the secondary battery can feed the data or any other circuit. Shut off the primary battery kill swich and the voltage feeding the secondary relay pickup coil will die. Now the high amp contacts are open removing power the secondary battery was feeding. This type of relay can be found in 25/40 /70 Amp and higher ratings. Problem solved. :cheers:
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What does SCTA=BNI say. They have to approve it.
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What does SCTA=BNI say. They have to approve it.
Today I talked to the SCTA Tech Advisor Jeff Arnett he approved this method of shutting down the forward battery power.
As long as the relay is open when power is removed its good. :cheers:
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Ron....It is always a good idea to have some written evidence of your conversation in your Inspection/Entry/Build folder. You would be surprised how many times we have been yelled at when Inspecting a Car and we have found something lacking, or even downright unsafe. The screaming usually starts off `Well I talked to so-and-so and He said it was good to go....`Even when this is indeed correct, it is usually very hard to locate `so-and-so` when the car concerned is in the middle of Inspection....
I`m sure Jeff would be happy to send you an Email that you could keep with your stuff, along with a few photos if the parts are hard to get to or see, and some specs on the pieces used.
Anything that will help you have a seamless trip through our little area will make your week better...
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Kiwi Paul Thanks
I will send Jeff an Email so I have wriitten evidence about the approval I will add it to my paper work for proof if there's any doubt during inspection.
Ronnieroadster