electrical question re: watts, amps and cable

Also what if one of the paralleled 10A cables falls off or is damaged? The remaining one will then be overloaded.
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And what if the 20A cable is damaged or some of the multiple strands fail ?
And have you seen the tolerance on the current required to blow your average auto fuse :eek: :eek: :eek:

We all ride motorcycles and therfore need to take a sensible view of risks.

Personally I'd be confident enough in my ability to install a twin feed so that the chances of failure would be small. YMMV.
There are likely to be many other things on a 1200 that may fail first . . .

Although auto fuses are very variable in the current required to blow them (oh er misses) they tend to "fail safe", ie corroded contacts would cause an open circuit rather than an overload.

But what of the CANBUS ? I've have no design drawings for the BMW implementation but I suspect a single component failure could result in no current protection for a circuit :nono
 
Paul90 said:
But what of the CANBUS ? I've have no design drawings for the BMW implementation but I suspect a single component failure could result in no current protection for a circuit :nono
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They're all like that Sir - there's no demand for it you see...
 
What size cable are you using if it's rated at 10 Amps. Standard grade cable 1mm is rated at 8.75A, 2mm is 17.5A. The insulation on standard grade cable is only rated at 85 Deg C You need to downgrade the current rating of the cable to suit the highest ambient air temperature it will pass through - this will be quite hot under the tank of your bike in summer so your wiring is probably not up to the job.

You should be using Tri Rate or better still Thinwall cable. Thinwall 1mm is rated at 16.5 Amps and the insulation to 105 Dec C.

Of course you could ride round in happy ignorance on your mobile incendary device :)
 
kinnell - I thought it was a simple question to ask.
I'm not looking for a bodge just don't want to have to go to the national grid for a bit of wire to run from the battery to my relays.

I'll buy some thicker stuff rated at > 18.3 amps :beerjug:
 
If you want some posting to you FOC send me your address. My email is rob_farmer (@) btinternet.com Obviouslly with the ( ) and spaces removed :thumb

I've got some thinwall 2mm, rated at 25Amps

I take it you are using 2 relays? one to swtch the extra circuit on and a changeover relay, switched from the high beam circuit, to change the lights over with dip and main....Or is sir looking to melt the tarmac? I've got a stack of automotive relays if you want one.
 
Current

yes, in the good old days of Vincent electrics and Joe lucas dynamos one did'ent worry hardly enough amps to blow a fuse!, assie quote, "why do the poms drink warm beer"- "Joe lucas makes the fridges"!.
(for all the youth out there Joe lucas as known as the prince of darkness)
dave (dim) GS.
 
Paul90 said:
. . and whatever you do don't let the smoke escape from the wiring loom or you'll be stuffed :augie
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Thats it. Its a misconception that wires are electrical conductors, they are infact very small sealed tubes for smoke to flow through :)
 
robb said:
Hi question for the more electrical minded amongst you,

I'm looking to feed a relay directly from the battery that could power 4 55watt spots at the same time (2 dip and 2 mainbeam). Peak load is therefore around 18 amps.
I have 10 amp cable supplying each pair of lamps from the relays can I just use two strands of 10 amp cable in parallel or do I need to go out and get some heavier duty stuff for the initial feed?

thanks in advance...Rob
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All

Just to throw another spanner in the works!

Surely if you want 2 lights on dip and 2 on main beam you will require 2 relays. So using 2 relays will mean that each pair of lights will have separate circuits therefore 2 10A cables will work anyway!

Ian
 
ianm00 said:
All

Just to throw another spanner in the works!

Surely if you want 2 lights on dip and 2 on main beam you will require 2 relays. So using 2 relays will mean that each pair of lights will have separate circuits therefore 2 10A cables will work anyway!

Ian
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True but I'm putting one before the two you mention that will be controlled by an autoswitch so I can turn the lights off and on. 3 relays in all and the first one needs to take all the load.
 
Rob Farmer said:
If you want some posting to you FOC send me your address. My email is rob_farmer (@) btinternet.com Obviouslly with the ( ) and spaces removed :thumb

I've got some thinwall 2mm, rated at 25Amps

I take it you are using 2 relays? one to swtch the extra circuit on and a changeover relay, switched from the high beam circuit, to change the lights over with dip and main....Or is sir looking to melt the tarmac? I've got a stack of automotive relays if you want one.
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Thank you kind sir - an email is on the way. :beerjug:
 
robb said:
kinnell - I thought it was a simple question to ask.
I'm not looking for a bodge just don't want to have to go to the national grid for a bit of wire to run from the battery to my relays.

I'll buy some thicker stuff rated at > 18.3 amps :beerjug:
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The simplest questions often have the most complex answers.
Using the higher rated cable is the correct thing to do (as well as the neatest).

However - dare I say.

1. If you take a 20A(ish) wire directly from the battery then you should include a 20A inline fuse before it goes to the relay..

2. I assume that this 20A(ish) wire then goes to the relay input and on the relay output you have two 10A(ish) wires.

If my assumption of 2. is correct then, under certain fault conditions either of the 10A(ish) wires on the output side of the relay could be asked to pass up to 20A for long periods of time and therefore be overloaded. Strictly speaking to avoid this situation each of the 10A(ish) circuits should also be fused to 10A. Alternatively use the 20A(ish) wire throughout the circuit.

At a previous company I was asked to do a 'quick simple cheap design' to take a 12V 20A power supply and add 10 cables and connectors to the output (to feed 10 battery chargers) each one of these cables was rated at about 2A.

I insisted that each 2A output should be fused, the boss said this was unnecessary and he went ahead with his un-fused design - I protested and refused to have anything more to do with it.

Several weeks later a customer (a local police force) reported that the wiring had caught fire when the chargers were unattended over night! One of the battery chargers had failed and had tried to take all 20A from the power supply through one 2A cable! We had hundreds of these things retuned and I was then allowed to redesign it properly.
 
robb said:
True but I'm putting one before the two you mention that will be controlled by an autoswitch so I can turn the lights off and on. 3 relays in all and the first one needs to take all the load.
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Robb, You only need two relays. One to switch the power on/off to the lamps and a changeover relay to switch between the high/low setup. The changeover relay can be switched from the high beam circuit (white wire on the LH switchgear connectors - under the tank at the front). The Autoswitch controls the main on/off relay - this puts power to the changeover relay. The normally closed contact of the relay goes to the fog lamps. The normally open to the driving lamps. When you switch on the main beam the relay is energised switching off the fog lamps and bringing on the driving lamps.

Looks like I'll be sending you a pair of relays to do the job and a connection diagram :D I'll have a look to see if I've got a complete harness left over from when I did the lighting kits. If I have (and I may not) then I'll put the install guide in with it.

The relays are rated at 30 or 40 Amps so are well up to the job.

:thumb
 
Bullshit

Remenber the old saying "bullshit baffles brains"!.
dave ( baffled) GS.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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