Relay/Fusebox Best Practices?

Techbiker

New Member
Oct 27, 2009
165
2
0
DFW, Texas
As I am collecting parts for my XR-80 board track racer build, I'm focusing on building a reliable electrical system. I plan on having the following:

-Ecotrons EFI kit with 2.5 amp fuel pump, CDI, etc.
-2 amp headlight
-5 watt tail light
-turn signals
-car/motorcycle horn
-Trail Tech Vapor digital guage
-Phone holder/ charger?

-3700mah battery
-DC regulator/rectifier
-100 watt stator

Coming from the car world, I use relays and fuses for each component. In fact, I was planning to purchase a micro relay box for this xr-80 build. I couldn't find anything for motorcycles however.

Should I use the PC-8 switched fuse box (to make sure that nothing drains my battery), then an additional relay for the headlight? I'm not sure if it's smart to run 2 amps through a cheap headlight switch.



http://www.easternbeaver.com/Main/Wiring_Kits/Fuseboxes/PC-8/pc-8.html#30akit

See my build thread here!

http://motorbicycling.com/showthread.php?t=54822
 
Last edited:

Davezilla

New Member
Mar 15, 2014
2,707
6
0
San Antonio Texas
That fuse box looks nice and will make for a clean install, I'd use it. and for the lights, I'd definitely use a relay to protect the switch and for the fuel pump I'd also run a relay and use a circuit breaker instead of a fuse just simply because if you're out somewhere and your fuel pump or ecu fuse blows, you're pretty much stuck unless you carry a spare. If you just run it at the track fuses will do just fine. I'm just really anal about certain electrical circuits because there's not much worse than being 5 or 10 miles from home and the fuel pump or efi fuse pops for no reason... Everythign else you can still get home. You can get aircraft style circuit breakers anywhere from 1/4 amp all the way to 100 amps or more and they're also nice and compact. Their prices are pretty much based on amperage but can be had for around $10 or so for a 2 to 5 amp breaker.
I've read thru your other post earlier and that looks like it's gonna be a sweet ride when you're done.
 

BarelyAWake

New Member
Jul 21, 2009
7,206
9
0
Maine
Jus' a FYI - any automotive style blade fuse box can be converted to breakers with no more then these, there's other breakers less costly but I've used the Bussmanns with great success many times & they've always worked well for me & BTW, the part number's suffix is it's amp rating (UCB-10 = 10a);

http://www.amazon.com/Cooper-Bussmann-UCB-10-Circuit-Breaker/dp/B000Q0AVHQ


...ofc, having said that I've still not gotten around to replacing mine on the taddy, they're usually easily found at any auto parts place... just not near me it seems lol

Here's the taddy's relay, buss bar & fuse panel jus' as an example, right relay is for activating the 36v electric drive w/the 12v system's keyed switch, middle (round) is the LED blinker relay, the left is for the four stroke's electric starter switch - the lights are all low-amp LEDs & the 12v scooter horn is low draw as well so I didn't bother to relay those;

 
Last edited:

Davezilla

New Member
Mar 15, 2014
2,707
6
0
San Antonio Texas
That fuse box looks great! Nice clean install... and I forgot about those thermal breakers, those will work just fine as well, they can't be reset manually but they'll get ya home once they cool down after tripping and they're about 1/3 the cost of the aircraft style breakers and can plug right into the fusebox without more modification, I like it, still much much better than a fuse for the fuel pump or efi.
 

2door

Moderator
Staff member
Sep 15, 2008
16,326
123
63
Littleton, Colorado
I used to use circuit breakers instead of fuses for headlights, fuel pump and electric radiator fan but...Two summers ago I had an underdash fire that could have been a disaster had I not had a fire extinguisher on board.

The initial problem was ultimately traced to a defective radiator cooling fan motor. When it shorted internally it popped the breaker but then the breaker reset and then popped again. I was using good quality Buss breakers that reset when the amp/thermal load is taken off. It was night and my only indication that something was amiss was the headlights would dim slightly then recover. After the third time I started smelling smoke and then saw the glow of fire on the floor near my feet.

I got the fire out quickly, drove home and the next day found the fan circuit breaker had caught fire and cooked everything close to it. Directional light flasher and associated wiring, wires that fed my overhead console and a windshield wipers, etc.

I replaced the cooling fan motor and replaced all my breakers with fuses. And yes, I feel in most cases breakers are preferable to fuses but in this case had a fuse blown I would have not had to rewire a portion of the electrical system or run the risk of a catastrophic fire that could have destroyed my hot rod.
Just one man's experience.

As for the question about choice of switch verses horn amps, most switches will have a 'contact rating' on them to tell you the max circuit amps they will take. I typically use the 125% rule. Take the known amp draw of the device and multiply it by 125%. That will give you a safe margin when choosing a switching device or planning your fuse/breaker capacity.

Tom
 

Techbiker

New Member
Oct 27, 2009
165
2
0
DFW, Texas
Thanks for the tips. I went ahead and ordered the PC-8. Unfortunately, I cannot find any ATM (mini) size breakers that will fit in the Eastern Beaver box though. I will certainly plan on carrying extra fuses with me in case one blows.

Tom, that's my main concern with breakers. I would almost rather blow a fuse and be stuck than to have my bike catch on fire.

Dave, this fuel pump is pushing enough fuel for something as large as 125cc's or so. Do you think I could purchase a potentiometer to drop the voltage to the fuel pump in order to save power? My Z uses a controller that reduces power to the fuel pump during idle and cruise conditions. I will definitely use relays for the pump and headlight though.

I just got a great deal on some OEM Harley Sportster handlebar controls. These things sure are beefy! It's too bad I don't have electric start, however I could probably use the button for something else.



Thanks again
 

Attachments

Davezilla

New Member
Mar 15, 2014
2,707
6
0
San Antonio Texas
Wow... the thing that was supposed to protect your curcuit and prevent a fire is what actually started it... Good thing you were able to get it home safely.
I do the same thing when wiring anything on my cars or bikes and go up a few gauge sizes to keep everything running cool and the 125% rule is definitely a good rule to follow as a minimum wire size, they do get rather hot when the circuit or components are running at max power.

You can use a potentiometer to reduce the power going to the fuel pump but like mentioned, use the 125% rule and get one that can handle more power than it'll have to control. So let's say figuratively that the pump needs 2 amps to run at full power, we multiply 2 amps times 12 volts, that gives us 24 watts, now that we know the pump is 24 watts, we're going to buy a potentiometer that can handle 30 watts, which will keet the potentiometer running cool. Now a 24 watt potentiometer might be hard to find or expensive and that's where a more solid state controller comes into play, usually thru a transistor or mosfet along with a decnt size heat sink to choke off the current going into the pump... which is pretty much what a pump or fan controller is made with, a lower power potentiometer and a mosfet or series of mosfets, there's more to the circuit than that, but this is the general idea.

You'll love those harley controls, All the Harleys use 1" diameter bars instead of 7/8" so you also get to use the more beefy bars using these, you can also slip sections of 1" bar over the 7/8" bar and weld them or cut your 7/8" bar and weld in the 7/8" bar to hold the grips and controls, but there's enough 1" options that you should be able to find what look or feel you want, no problem there.
One of the things I really like about Harley controllers is that the turn signals are on both grips instead of a 2 way switch on the left side, this took me all of about a day or less to get used to, and they also use auto cancelling turn signals so you could find a turn signal controller on ebay pretty cheap so your signals stop flashing once you complete your turn, but they can be wired for manual shut off easy enough too.
The throttle should also have a built in tension adjuster under the grip which is nice on long rides as it can be used as a cruise controller by setting the tension just high enough to keep the throttle from returning on it's own. Another plus here is that you can get the control housings or buttons in black or chrome without having to buy the whole controller.
I eventually want to put Harley controllers on my other bike, a Suzuki Intruder 1400 just because I like the Harley layout much better.

You mentioned you got a Z... Which Z do you have? I had a '79 280zx, a 70 240Z and currently own a '90 300zx
 

Techbiker

New Member
Oct 27, 2009
165
2
0
DFW, Texas
You can use a potentiometer to reduce the power going to the fuel pump but like mentioned, use the 125% rule and get one that can handle more power than it'll have to control. So let's say figuratively that the pump needs 2 amps to run at full power, we multiply 2 amps times 12 volts, that gives us 24 watts, now that we know the pump is 24 watts, we're going to buy a potentiometer that can handle 30 watts, which will keet the potentiometer running cool. Now a 24 watt potentiometer might be hard to find or expensive and that's where a more solid state controller comes into play, usually thru a transistor or mosfet along with a decnt size heat sink to choke off the current going into the pump... which is pretty much what a pump or fan controller is made with, a lower power potentiometer and a mosfet or series of mosfets, there's more to the circuit than that, but this is the general idea.

You'll love those harley controls, All the Harleys use 1" diameter bars instead of 7/8" so you also get to use the more beefy bars using these, you can also slip sections of 1" bar over the 7/8" bar and weld them or cut your 7/8" bar and weld in the 7/8" bar to hold the grips and controls, but there's enough 1" options that you should be able to find what look or feel you want, no problem there.
One of the things I really like about Harley controllers is that the turn signals are on both grips instead of a 2 way switch on the left side, this took me all of about a day or less to get used to, and they also use auto cancelling turn signals so you could find a turn signal controller on ebay pretty cheap so your signals stop flashing once you complete your turn, but they can be wired for manual shut off easy enough too.
The throttle should also have a built in tension adjuster under the grip which is nice on long rides as it can be used as a cruise controller by setting the tension just high enough to keep the throttle from returning on it's own. Another plus here is that you can get the control housings or buttons in black or chrome without having to buy the whole controller.
I eventually want to put Harley controllers on my other bike, a Suzuki Intruder 1400 just because I like the Harley layout much better.

You mentioned you got a Z... Which Z do you have? I had a '79 280zx, a 70 240Z and currently own a '90 300zx
Dave,

Scott @ Silver State Cycles is going to bend me a custom 1" diameter handlebar as part of the build. When he's done with the drive-train, frame, etc. I will test fit the controls. I can't wait to see how it all turns out. I wonder if it's worth going with internal wiring on the handlebars? I've heard that it does wonders for the look.

I've heard the same thing about the Harley controls. It seems that most guys really like them and the design is very intuitive. Why on earth would anyone sell a bike with a turn signal "selector" on one side? To each their own I guess.

Regarding the turn signals, I found the Badlands Illuminator Pro III. It seems to integrate nicely with the Harley turn signals, connects to the indicators, and controls the signal lights as well (11 second auto cancel). Do you think this is a quality box? It would be neat to install a tilt sensor to cancel the signals though.

http://www.namzcustomcycleproducts.com/images/ILL-PRO-III.pdf



I could see what else is out there as far as controllers go.

I'm going to try running the fuel pump at full voltage at first, however I will explore solid state controllers if I need to save more power.

It's a cool coincidence that you own a 300zx! I drive a 1993 2+2 and trade off working on my motorbikes and my Z. Are you a member on any of the Z forums?
 
Last edited:

Davezilla

New Member
Mar 15, 2014
2,707
6
0
San Antonio Texas
You could route your wiring thru the bars which makes for a very clean install, just protect the wires either with an extra layer of heat shrink or a grommet on each hole in the bars to prevent chafe thru and early failure by shorting out etc... teflon anti chafe tape works good for this, but heat shrink, or a teflon sleeve will do as well, with the teflon stuff being superior in chafe protection. also, any holes drilled should be deburred really well for even better chafe resistance.

That Badlands box should do the trick just fine, I'm not familiar with that brand but it does look like it's built really well and being American made it should be built to last.

Cool that you got a Z32!! I've had that same car since 1998 and have done just about every upgrade to it except for converting it to twin turbo... and I'd still like to do that one of these days. I used to frequent twinturbo.net but I hadn't posted in there in years... This car is kinda on the back burner for now since it needs a new paint job pretty bad, it still runs like a scalded chicken and handles like a cat on carpet but it's exterior is really showing it's age, the interior and under hood still look new. I do paint for a hobby and am capable of doing the painting myself but need to rent a paint booth or take it somewhere where I can do it since I can't paint in the garage anymore... we also have about 40 parrots in the house and the fumes would kill them pretty easily so my painting with automotive grade paints days are over until I get a place to do it again.
The Z has a Z1 stage3 ECU, headers, full stainless exhaust, Stillen/JWT intake and K&N, underdrive pulleys and electric fans, a Fidanza aluminum flywheel, and a bunch of goodies I'm sure I forgot to list.. lol. I also got an 86 Nissan 4x4 pickup that I've done a ton of mods to as well so I do go between focusing a lot of my efforts on the truck, the Z, and my 3 motorcycles, a Harley Sportster, a Buell Blast, and a Suzuki Intruder 1400... and now these little motorized bikes...