Honda CBR600FX Elec Q's

[erny]

1. Anyone have a rough idea of the current the starter motor uses? i know cars can be up to a few hundred amps, but have no idea for bikes.
2. Anyone have a wiring diagram for the original wiring loom for this bike?
3. The starter motor relay that came with the bike loom has a 30A fuse, surely this is not for the starter motor circuit itself, but seems to high for the relay coil circuit. Any ideas?

[erny]

1. Anyone have a rough idea of the current the starter motor uses? i know cars can be up to a few hundred amps, but have no idea for bikes.
2. Anyone have a wiring diagram for the original wiring loom for this bike?
3. The starter motor relay that came with the bike loom has a 30A fuse, surely this is not for the starter motor circuit itself, but seems to high for the relay coil circuit. Any ideas?

[Jon @ Electromotive, Inc.]

The 30A is the main fuse for the electrical system. I does not directly effect the starting circuit.

I'm not sure myself how much current the starting circuit will need. Plan for at least 100amps(maybe a little more).

Check the design links topic. There is a link in there that has repair manuals for most bikes out there.

[Erich Ohlde]

I've put an ammeter up to the starter wire during the cranking cycle and seen ~40-45 amp draw. However there will be surge currents 5-8 times that from the time the starter is at 0 rpm to full cranking rpm. Why do you ask the question about the cranking amps necessary? wire sizing?

[C Z]

How many fuses did you blow when you wired our car Erich???????????????????????????

[Erich Ohlde]

lol. and then i figured out that fusing that was really stupid http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Chris Boyden]

I wouldn't say that it's stupid to fuse
the starter via the main fuse from the battery.
100 amp to 150 amp fuses are available.
These can protect the battery from major currents like the kind generated when people decide to weld the chassis with the hot lead.
They can deal with the surge because they are slow blow fuses. I measured a 50 amp draw using an old inline ammetter.

http://www.bussauto.com

[erny]

I ask about the current as i havnt seen any relays that handle hundreds of amps, although my search did not last longer than 2 minutes.

Cheers for the help with that fuse

What kind of general purpose relays do you guys use or rather how do you connect them into the loom? Crimp terminals? Relays with screw terminals? PCB?

I have just made a relay PCB, but have not tested to see if the track burns out yet with the current.

[raska]

Other than the starter relay all come from the 'Power Box' which is a PCB with all the fuses, relays, and a optocoupled, MOSFET driven DC power supply for each component/section of the car.

There are some formulas out there for calculating the trace widths, but here are some simple little calculators: http://www.ultracad.com/calc.htm

As a reference, we've been using 250mil wide traces fused up to 30A for years, on a simple uncooled, unsoldermasked PCB inside a enclosed box. Never had problems.

The relays being used are some stubby PCB mount Tyco ones, but I'm looking for an even smaller or alternative method to using them, to shrink things down some more.

[Erich Ohlde]

don't use a relay, use a soleniod (similar to the one that comes stock on the bike). Relays can't handle the kind of current that the starter draws. Worse case scenario: Relay fuses and the starter won't stop cranking. IMO it works best to use the stock Solenoid with 10/8 ga wire. I've done this on two SAE cars and have had zero problems

[raska]

A common method of relay construction is with an internal coil which creates a magnetic field used for mechanical actuation. A coil used for it's magnetic field properties is often termed a solenoid. So using a relay is a good idea, just choose it correctly.

[DaveC]

There is a cheap, small, extremely common relay thats rated for 85A continuous, much more intermittent. They are also used in electric golf carts. If you called any (decent) auto parts store and asked for an 85A continuous duty relay, they should find it for you. Its a small silver cylinder (2"x3" ?)that probably weighs a few ounces. You probably could use a much smaller relay, but you'd really need to test starter draw. It will draw different Amperages depending on load, so be sure to give yourself a good safety margin, and account for start up draw as well.

Of course, if you have the stock solenoid, youre good to go...

[B Lewis @ PE Engine Management]

Just make sure to use something in the starter circuit (bike solenoid would be my choice). The effect of omittinig one and just running the starter current through the starter switch can add enough resistance to drop the cranking speed by as much as 150 RPM. This can be a real problem when trying to restart during the Endurance.

[Chris Boyden]

If you don't want to run the bike starter relay (solenoid), try
Stancor 120-901 from Newark.com
$15 bucks. 100 amp continuous 400A surge. plastic body. It may be cheaper than a bike relay solenoid if you don't already have one.