Wiring questions

[nickmpower]

Im doing the wiring for my team, and so far i plan to use the stock harness. Some of the wires need to be lengthened or can be shortened and Im wondering what the best method to go about doing this is. I have searched but it seems like most of the threads are for someone building an entire harness. It seems like my main options are either to soder or use butt connectors. Now butt connetors can fail if not done right, but sodering seems like it is pretty brittle and could break pretty easy if very much load is put on it. Right now Im leaning towards butt connectors but what do you guys think?

also, for the master kill switch, how many of you are cutting the battery and alt wire and how many of you are cutting the ground wire(or is this even allowed)?

Thanks for your input

[nickmpower]

Im doing the wiring for my team, and so far i plan to use the stock harness. Some of the wires need to be lengthened or can be shortened and Im wondering what the best method to go about doing this is. I have searched but it seems like most of the threads are for someone building an entire harness. It seems like my main options are either to soder or use butt connectors. Now butt connetors can fail if not done right, but sodering seems like it is pretty brittle and could break pretty easy if very much load is put on it. Right now Im leaning towards butt connectors but what do you guys think?

also, for the master kill switch, how many of you are cutting the battery and alt wire and how many of you are cutting the ground wire(or is this even allowed)?

Thanks for your input

[Superfast Matt McCoy]

Butt connectors have no place on these cars. If you need a connector, use a good one. If you don't need a connector then solder it and use heat shrink. The strength of a soldered connection under load shouldn't even be an issue. If there are any forces acting on your wiring other than G forces, there is something wrong.

If you're using a power commander then it might be easier to use most of the stock wiring. If you're using a standalone ECU, you should probably build a harness.

I think the rules are pretty clear on the kill switch wiring.

[exFSAE]

Butt splices can go straight to hell. I wouldn't use em for anything, FSAE or otherwise.

Stranded wire, soldered and heat shrunk (shrinked?). You would be amazed at how strong those connections are! Do it right, and you can pull at em with a heap of tension force and it won't budge.

As for actual connectors.. Deutsch or Autosport connectors are the f'in bomb. And LADD sponsors FSAE teams really nicely.

[nickmpower]

Alright, I'm going to be sodering


I will also run the red power wires from the recitifier/regulator through the cut off, assuming these are the right wires to cut the alternator?

[Prohet][]

When disconnecting power from the alternator just make sure the battery won't still be connected to the rest of the circuits. Sounds simple but need to watch out for it.

You also don't want to cut ground as a loose wire could hit the chasis and power the car.

Interestingly, last year we didn't have a cover on our negative pin on the battery since the rules say you don't need one. We got told to put one on incase something like the seat or chasis touches it. But it was already connected to the seat and chasis on purpose. Nothing a bit of race tape can't fix though.

[BrendonD]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by exFSAE:
Butt splices can go straight to hell. I wouldn't use em for anything, FSAE or otherwise.

Stranded wire, soldered and heat shrunk (shrinked?). You would be amazed at how strong those connections are! Do it right, and you can pull at em with a heap of tension force and it won't budge.

As for actual connectors.. Deutsch or Autosport connectors are the f'in bomb. And LADD sponsors FSAE teams really nicely. </div></BLOCKQUOTE>

Ditto on that one, it's not that hard to do either. You won't significantly impact the time you'll spend wiring in connections over soldering. Once you have a system down it goes REALLY fast.

Clip, Strip one side, Strip other side, put on heat shrink, wrap wires, solder, wait for solder to cool, apply heat to heat shrink tubing in proper location and you're done. You can get this down to 2 minutes per splice if you're cookin.

[JaredC]

There's quite a few misconceptions about wiring.

Wire soldering is not ideal for any high performance or high reliability environment - race car, aircraft, etc. It is brittle and will crack and break over time. The wire doesn't have to be stressed or pulled on to break. Vibration from the engine alone will kill it. It's not a matter of if, but when. You may survive through competition, but you may not, and who needs another reliability risk?

Having said that though, cheap crimps are even worse. Cheap crimpers are just plain crap and are a recipe for disaster. Invest in a good set of stamped and formed pin crimpers with the correct sizes and a decent set of adjustable solid pin crimpers and you will be set. Grab a set of ratcheting insulated terminal connector crimpers and don't look back. Perfect termination every time. Get some stripmaster wire strippers for a perfect strip every time. It will make life so much easier and give you a much more reliable result.

Soldering has way too many variables, so even if you ignore the fatigue cracking issues, it is impossible to do the whole car perfect. It just won't happen. It is just not a repeatable process and it is far too easy to make a mistake, particularly if you are rushing, have been up for a while, are working in an awkward position, etc, etc. It's pretty hard to screw up squeezing a ratcheting set of crimpers until they release. It is a much more controlled process.

Getting good quality tools and terminals isn't cheap. Budget $2k for tools, and $1 or so per terminal.

If you can afford it, get some Raychem environmental butt splices. Use deutsche/autosport connectors. Use tefzel wire. Do not use cheap crimps at all. If you can't afford the good shit, then you need to go to plan B.

If (and only if) you are tight on money, you will have to resort to soldering and heatshrinking. Invest in high shrink ratio clear glue-lined heatshrink. Use it properly and don't try to do anything dodgy because it will bite you in the ass. Strain relief will help keep the solder joins happier for longer. Weld tabs or epoxy mounts in place along where you want to run the loom and cable tie to them. Pay particular attention around connectors and wire joins. Don't tie on or within an inch of a join. Make sure you have at least one cable tie on each side of a join 1-2 inches away. Make solder join inspection a maintenance item. Route wires and place joins in visible locations so you can check them through the clear heatshrink easily.

[Mustang Mac]

I have to agree with JaredC, Take the time, and budget, for the proper wiring and tools to complete it. Soldering is just asking for trouble, one more variable you have to worry about. We manufactured our harness with autosport connectors, teflon wire and Raychem, epoxied some major connectors and had a fully water tight harness, that looked amazing, gave us no issues over the last 3 years and won over the judges.

[Renato]

has anyone already had a problem caused by transient when sutting off the master switch?

[Steve O]

Despite the fact that I have some solder on my car, I agree that solder, especially if not done correctly, is asking for much more trouble than high quality crimps. If you do plan on soldering, make sure the wire draws the solder in and that you are not just putting it on top... basically put a dab of solder on the tip of the iron and heat the wire until you see it suck it up, at that point place solder somewhere on the wire other than directly where the iron is and you will see the wire draw in the solder, for a good connection you should feel the wire hardened with solder a good 1/4-3/8 inch inside the insulation on each side. Keep in mind that things don't all like heat and you will end up with cracked wires and broken switches if you heat it up too much... use a variable temp soldering iron.

On a separate note, in response to Renato, any inductive circuit will have negative slapback which will do what you are saying even if your alternator is disconnected when turning off the master switch. The best way to fix this problem is with a spdt switch and ground out whatever signal you are cutting or put a bleed off diode across the switch.

Best way to demonstrate the effectiveness of this is to take a DC fan of sorts with good bearings, power it up and disconnect the positive terminal count how long it takes it to stop. Take the same fan power it up, pull off the positive signal and place it on ground. Your fan should stop immediately, almost as if someone turned on a brake and, in fact, that is exactly what you did because you drained charge from the inductor which continues to power the circuit as the fan spins down. In power electronics, we refer to turning off a circuit as freewheel mode and grounding everything as stop mode. In fact when doing this experiment, you will even see a perfect example of why the ONLY inductor that should ever be left as an open circuit is a spark plug. The positive terminal will spark as you put it to ground, even though you have no power hooked up to it!

A true EMG shutoff on any inductive circuit takes all positive terminals (on the load side, not the power source side!) on the circuit and puts them to ground instead of just disconnecting them from the battery for a stop mode. I will attach a picture later on when I get home from work, my ftp isn't working properly from my "borrowed" wifi here in my ambulance in this parking lot.

Steve

[Kai69i]

Yep, high quality crimping each and every time in your loom; soldering is not a long term solution.

Tefzel wire, Deutsch connectors, conventions, and high quality heat shrink- the other requirements.

If the crimping/stripping tools (typically you will need 4) cost you less than $2000, then they are not good enough for building a loom with. It sounds like a substantial outlay, but look after them and they will serve your team for years to come.

If it looks good, then it will work well. Garbage in = garbage out.

I cannot think of any exceptions to these rules!

All the best with your loom,

Kai

[Renato]

thanks steve
i'll be waiting for the picture

[nickmpower]

damn, you guys make twisting wires together seem better then butt connectors and sodering!!!!

also is it correct that I want to cut the red wires from the regulator? seems like it i just want to make sure im right!

[screwdriver]

If you've got a login on the FSG website, there's a full wiring diagram of the battery circuit in the "Rules/ Important Documents" section.

Note: This and some other documents only become availible if you are logged in.

Link is here http://www.formulastudent.de/uploads/media/20060411_Gui...master_switch_01.pdf (http://www.formulastudent.de/uploads/media/20060411_Guideline_for_electrical_systems_and_mast er_switch_01.pdf)

[murpia]

That FSG link drawing to show a twin-circuit master isolator so the alternator and the battery are isolated from each other if the master isolator is off. That's supposed to be bad for the alternator...

The photo however shows a single circuit master isolator so the alternator and the battery will remain connected to each other when the master isolator is off. That should be OK for the alternator.

What do you use?

Regards, Ian

[nickmpower]

could the regulator/recitifier wires simply be connected straight to the battery? then only the battery cable would need to be connected to the kill switch?

[Renato]

you have to turn of all electrical circuits, including the alternator.

i think if you do not disconnect the alternator, it could have a feedback from the field coils, that's why the rules order us to disable any alternator field wire.

am i right?

[kmrobinson]

Our team failed endurance due to a loose pin inside our MoTeC main harness connector. Unfortunately, we had purchased the harness from them, rather than doing the assembly work ourselves. Hence, a valuable lesson on wiring: do it yourself, because that's the only way you'll know it is done correctly.

Spade connectors and butt connectors are terrible. Our car was wired with these and I regret that we did that. On a street vehicle, they might be sufficient, but for our application they are extremely failure prone. Don't go cheap on wiring. Our DAQ system was done with soldered Binder connectors and they are worth every penny we paid. It takes a little more time, but it is worth it.

[murpia]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by nickmpower:
could the regulator/recitifier wires simply be connected straight to the battery? then only the battery cable would need to be connected to the kill switch? </div></BLOCKQUOTE>

I think so, but the alternator field control supply must be connected the other side of the master switch (as the FSG link shows).

Regards, Ian

[Steve O]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
Spade connectors and butt connectors are terrible. Our car was wired with these and I regret that we did that. On a street vehicle, they might be sufficient, but for our application they are extremely failure prone. Don't go cheap on wiring. Our DAQ system was done with soldered Binder connectors and they are worth every penny we paid. It takes a little more time, but it is worth it. </div></BLOCKQUOTE>

As mentioned before, you are right in regards to connectors you get at autozone, but if you get high quality crimps and crimpers the connections will be far superior to solder or cheap butt connectors. Solder will fatigue and crack from the vibrations on these cars. I use both depending on the location on the car and what it is for. As far as spade connectors are concerned, I agree they are dangerous, unless it is for a non-critical accessory that if it pops off you are still good. Anything on our car with a spade is there because it has to be (i.e. our fuse box has spade terminals) and the spade connectors are soldered in place as insurance.

Steve

P.S. As promised, Renato, here is the diagram top is bad, bottom is good. Again, current sources should be shorted or loaded in a circuit (unless being used as a spark plug...which is exactly why you don't normally open...shock hazard.) and a voltage source should either be open or loaded. Most alternators are inductive current sources but the regulator rectifier makes it a voltage source... keep that in mind with your wiring.


http://amaranthineproductions.com/freewheel-vs-stop.jpg

[Chris Boyden]

the alternators on R6's and F4i's don't have "field" control. The field is provided by permanent magnets. Current is generated by doing work against by moving coils through magnetic fields of permanent magnets. Permanent magnets don't have switches on them that let you turn the magnet on or off.
Therefore, the you are switching the output of the alternator system including the rectifier/ regulator on or off. I suppose you could switch off the three phase output of the alternator output off, but that would require a switch with three poles and be tied into the master switch as well.

[Chris Boyden]

the zener diode regulator (very simple regulator, dumps all excess current to ground when the voltage rises above the zener voltage) on the output side of the rectifier regulator will shunt any voltages due to inductive effects to ground without additional circuitry. Smarter regulators will buck the current, lower stator temperatures due to lower currents, and unload the generator a bit, freeing up power as well.

Almost all if not all of the shindengen rec/regs
are three phase rectifiers that feed a zener diode.

[Renato]

steve

in case we have a system like the FSG link, i think the inductance of the alternator will not discharge into load, because the master switch opens the circuit, and there's no way for the current to flow through it. could it be right?


http://www.formulastudent.de/uploads/media/20060411_Gui...master_switch_01.pdf (http://www.formulastudent.de/uploads/media/20060411_Guideline_for_electrical_systems_and_mast er_switch_01.pdf)

[Steve O]

well as they pointed out, apparently, the rectifier for your particular engine should be doing exactly what I said for you, but to answer your question no... an inductor will discharge through an open circuit...aka a spark plug. Instead of thinking there is no way for the current to flow through, think of it as there is no where for the current to go but it is determined to go somewhere anyway. Therefore, it either sparks at the opening or dissipates into your load.

Steve

[Renato]

i got it

and then, what switch can i use for this?

[Chris Boyden]

I don't understand the formula student link?

All the rec/regs I've seen don't have a 12V supply to the rec/reg?!?!? They have 12 V output (14 Volts for charging) and a ground lead.

Plus the diagram of the switch should include another pole. The picture is a 3 pole switch
If I remember correctly, one of the poles
is also normally closed and the others are normally open when the switch is "off".

Pole 1: NO (High Current)
Pole 2: NO (Low Current)
Pole 3: NC (Low Current)

[Renato]

Chris

in our car we have a similar rec/ret. that wire (12V supply) come into the IC, inside the reg/ret, to regulate the voltage.

i have a scheme of this kind of reg/ret. but i don´t know how to post pictures http://fsae.com/groupee_common/emoticons/icon_confused.gif
if you want, i'll post later

[Chris Boyden]

got a part number? is it made
by shindengen?

[Renato]

i haven't the number

tell me how to post a picture and than i put here

[mrrc]

We are running a Honda CBR 600RR engine and it runs the 3-phase alternator current into a rectifier / regulator part that converts the power to a stable 13 VDC. In this case, I don't think there is any extra work involved because the rectifier / regulator is taking care of protecting the rest of the electrical system, correct?