Con"fused".

[pjwooly]

Hi all.

Ok so I have connected a switch board to a fuse block which is connected to a spare battery then connected a LED light as the diagram (instructions) shows.

When I turn on the light only 4 out of the 12 LED globes lights up.

Is this a case of it being under fused?

I tried 1,5,10amp fuses and all same result.

Probly something simple I ain't seeing....

(I have hooked the light up directly and she works)

can anyone help please?

Pjw

 

[abouttogobush]

Not the fuses PJ LED's are polarity sensitive my guess is the one's not lighting are incorrectly wired. Reverse the connections on the terminals of the failed lights, also let us see the diagram you are wiring to.

 

[abouttogobush]

just reread my old eye's, you have a single unit with multiple led's my previous thought will not apply..

 

[pjwooly]

the led's (globes) not lighting up are part of the one light if you know what I mean.
(12 globes per light)..only 4 light up.

I will upload a pic if you like...

cheers.

 

[Old.Tony]

It won't be the fuse size. If the fuse is too small for the load running through it, the fuse blows - simple.

LED lights don't use a lot of power and the most common cause for them not working is being wired in backwards.

A photo would help us!

 

[pjwooly]

thanks guys just sorted it...the switch on the back has 3 connections...I was using one that was wrong.

Didn't look hard enuff at the diagram LOL

You really do have to look very closely to see where I mucked up but there you go...glad I got this right now.

HAHA just looked at my pics and it says 4. load to middle terminals so there you go!!

Thanks for your quick responses guys!!

 

[pjwooly]

sorted??...not quite ...haha

Just realised the light in the switch is not working now when turned "on".
Can someone please tell me what to connect this too.

tried a few ideas but could not get it to turn on and off with the switch.

 

[Old.Tony]

Ok, it's a little more complicated than it needs to be. You don't need a fuse AND a circuit breaker, but we'll overlook that for a moment. Let's look at the circuits in separate pieces so that we can be absolutely certain we don't get a "crossed wire".

BLACK WIRE - NEGATIVE
This guy never gets connected to red. Ever. Run the lead from the battery negative to the left side of the board in the photo like you have, run a black wire to the black wire on the LED light and forget it, black/negative is finished. No further connections on this side at all.

RED WIRE - POSITIVE
This is the side we generally switch and put fuses in. Your red wire goes from the battery to the right side of that board, which then passes power through a fuse and into the red wire attached to the middle, which runs off to the circuit breaker. If the circuit breaker is on (check it) it will pass power to that switch and if you have it wired like you do in the first photo, you have to flick the switch "off" instead of "on" to make the light come on. Change the lead that goes from the circuit breaker so that it doesn't join on the outer lug like you have it, but on the OTHER outer lug. Centre of the switch should go to the light.

Let us know how it goes.

Explanation of the switch: inside the switch is a 'rocker', it's like a see-saw. It balances on the middle connecting lug (so it's ALWAYS connected to the centre) and has a spring-loaded nib on a lever (with a central pivot) that pushes the rocker one way or the other. When you flick the switch off, the lever rotates around its pivot pushing the nib in the opposite direction, joining the other two connecting lugs. This means - holding the switch so that it flicks vertically up or down - when you push the switch down, the upper two connecting lugs are joined, and pushing the switch up connects the lower two lugs.

 

[pjwooly]

Cheers once again old tony you are a wealth of info mate very much appreciated.
Did as you said swapping the CB connections over and connected the outer tab on the switch to the neg bar and all good mate.

Regarding the CB button though could not get anything happening there mate.
When I press it what is supposed to happen?

Should the light go out when pressed in?

Thanks again.

Sorry damn pic is upside down bloody ipad

Pjw

 

[pjwooly]

So old tony while I may still have your attention......

Would I have been better off buying two bus bars for my neg and pos and using them as my power and earth source then going to the switchpanel to actually fuse my accessories?

It that how it's supposed to be done?

Cheers again.

Pjw

 

[Old.Tony]

The CB button does nothing unless the circuit breaker trips. The button restores the operation to 'normal'. It's just like the circuit breaker in your house.

Test it - really easy to do. Grab a new black wire, connect it to the negative of the battery and to one pole of an unused circuit breaker. Grab a new red wire, connect it to the other pole of the same circuit breaker you just connected the black wire to. Now touch the other end of the red wire to the battery - you're creating a dead short, the circuit breaker should trip and you should hear it click. You should now be able to press the button (you might need to wait 30 seconds for it to cool).

What you've bought is good. No need for two of them. The more components you introduce, the more complexity and the more places something can fail. Think of it like this: we buy just one length of wire to run power in to the tub of the car, because there are less joins and less things that can go wrong. We COULD buy one-metre lengths, put connectors on each end and put together half a dozen of them to do the same job. It would work - but EVERY join is something that can come apart, or corrode, and trouble-shooting a fault becomes much harder.

The KISS principle works in electrics as well.

 

[kernels]

Cheers once again old tony you are a wealth of info mate very much appreciated.
Did as you said swapping the CB connections over and connected the outer tab on the switch to the neg bar and all good mate.

Regarding the CB button though could not get anything happening there mate.
When I press it what is supposed to happen?

Should the light go out when pressed in?

Thanks again.

Sorry damn pic is upside down bloody ipad

Pjw

In that picture, you shouldn't have the negative running from the negative bus bar to the middle of the switch! With the switch switched one way, you will blow the fuse and the other way you will connect the positive of the led light to ground.

The power should go into one end of the switch and the go from the middle to the led light positive.

 

[pjwooly]

Thanks for the replies so far guys and I now have it sorted...

My next Q is with certain accessories and not knowing how to fuse them correctly.

How do I choose the correct fuse size for the accessory I'm connecting?

Cheers.

 

[bods]

If you know the wattage of it, it is easy to work out. Watts divided by volts equals amps. So foe instance a 10w light would draw about .83a... then just fuse accordingly.

Otherwise,if you know the amp draw of the device, normally go 1 fuse higher rated. So if you have a 12a item, then use a 15a fuse...

 

[mitch92]

Remember fuses are to protect cable, not devices. So only use a fuse rated at what the cable can handle.

 

[Old.Tony]

^ Indeed. Never use a fuse rated at higher than the cable can manage, but don't choose a fuse that's rated under what the device wants either. If your cable is not rated high enough for the device you're using, then you are using the wrong cable.

Simple guide: pick a cable that can handle at least 4 times the maximum power that your device will use. You can use heavier cable if you wish, but NEVER lighter. Long cable lengths require heavier cable again - anything past about 3m needs to be heavier. Pick a fuse rated higher than the draw - not a small amount higher, or the fuse will get warm.

Real world example:

A fridge draws 2.5A typically but draws up to 4.0A when it's trying to get the temperature back to where it's been set. The ideal cable for this over a short distance would be 20A automotive (multistrand) cable. Your fuse could be a 5A fuse but a 10A would be better.

Extending that real world example: let's say the device you're powering is 6m away. The equation changes but not because it's dangerous. It's voltage drop - yet another thing to consider with these relatively low-voltage systems. There are two possible problems over long cable runs.

Problem 1: long wires = increased resistance = increased heat. Reported on a few forums in relation to electric braking systems in caravans - so we're talking about 12V, and about 12A (two axles). However, we're also talking 10-12m of cable length. Over that distance, the voltage drops so the current rises - and this heats up the cable. I've read reports of wires melting through their insulators and shorting out - not what you want on Mt Ousley.

Problem 2: excessive drop = inoperable devices. We had a fridge (6.5A draw) in our caravan that would consider 11.4V the lower limit at which point it would switch off to save the battery. When you start placing a load on the cable, the voltage drops - in our case, a battery at 12.8V would lose 1.5V on the end of the cable and the fridge would turn off. The fridge would check again in 30 seconds, see 12.8V and try starting the compressor again, the voltage would drop once more ... it did this until it killed the battery. Replace the 40A cable (you'd think that was enough!) with 60A cable and it was good to go (voltage drop reduced to 0.3V over the cable length).

Clear as mud? Hope not!