12v Fuse Box - Power Without Fuse???

[Cham13]

This may sound like a really stupid question and I have double/double checked all wiring before asking it...the fuse box that I have fitted has power coming from it even without the fuses installed.

It has 1 main power into it which is connected to the leisure battery +, 8 tabs and I have fitted an earth block. If I make a connection (without a fuse installed), it sends power to the usb socket enough to charge the phone or partially illuminate a spot light. Once I install the fuse, the power increases, this is noticeable by the brightness of the spot light.

I would of expected there to be NO power without a fuse, is it faulty or is it me?

Without the fuse its reading 11 ish on the volt test meter with a fuse 12.84.

 

[Pauly]

Got any photos ?
It has to be getting power from somewhere, have you checked polarity from the battery ?
Are you sure it’s positive running through the box and not negative ?
Does the fusebox have lights for each fuse way showing if a fuse is blown ?
Have you commoned the negative on the leisure batt to vehicle ?

Give us a better idea of what you have done and how

 

[Cham13]

Hi Pauly, could be the earth as the earthing block is earthed to the floor and not the negative battery terminal?
If so, how does this make a difference?
The + (power) is coming straight off the leisure battery.

 

[Pauly]

Not sure, I was just trying to encourage you to ask the right questions and give more info to help provide some ideas

Potentially if polarity was wrong my train of thought was a permanent positive supply with a (poor) negative from chassis with fuse out then a good negative when fuse was in making full juice
My other thought was a fusebox with red light blown fuse indicators that could be making a partial circuit when fuse is out giving low voltage and a full circuit when fuse is in giving higher voltage ?
Some pics would be good to see what you have done

 

[Pauly]

Have you tried measuring an unconnected way with/without fuse that may give some clues if the fusebox is somehow letting through

 

[travelvolts]

This is normal if the fuse box has LED indicators.

 

[Cham13]

This is normal if the fuse box has LED indicators.

Hey 'travel volts' just realised you're from my home town of Kidderminster - small world!

May I confirm please? I've wired the fuse box (which does have LED indicators) directly to the leisure battery + and connected the + of the lights and USB sockets to the spade connectors of the fuse box.

I have then connected an earth cable (fitted to the ground of the van) to a small earthing block, to which the earth wire of the lights and USB sockets have been connected.

I have power to the lights and USB without a fuse being fitted, but when I do fit a fuse the power output does increase and the lights increase in brightness.
If you claim this is correct, then is it safe?

Over to you my friend!!!

 

[travelvolts]

All perfectly normal and totally safe.

 

[Cham13]

All perfectly normal and totally safe.

Cheers, nowt to worry about then.

 

[travelvolts]

No, the way that these fuse boxes work is when a fuse has blow a small current passes through the LED and goes to earth via whatever is connected on that circuit. With things like LED lights and USB sockets the current is enough to bring the light on very dimly. Other items that draw more power would not activate on this small current.

 

[Cham13]

No, the way that these fuse boxes work is when a fuse has blow a small current passes through the LED and goes to earth via whatever is connected on that circuit. With things like LED lights and USB sockets the current is enough to bring the light on very dimly. Other items that draw more power would not activate on this small current.

Can I just ask your advice, re. earthing the fuse box/earthing block....is is best to earth to the van or directly to the negative terminal of the battery? I need to finish off this job tomorrow and get everything working.

 

[travelvolts]

Direct to the battery is always preferable. However, if this isn't practicle then a good body earth is fine.

 

[brsnick]

Hi.

I thought I had the same/similar problem. For me its my Led light strips I've installed inside. They would stay on, very low, even when main fuse was disconnected from +LB

I have + from LB running to a +mounting block, then individual connections via spade connectors to Fuse box then out to Loads.

And - coming back into -mounting block and back to - on LB.

I realised my Earth from the LB wasn't connected to the chassis earth pin, so reconnected.

But now all other circuits on Fusebox are working correctly, but the LED fuse keeps blowing. I had this setup working with my old battery and controller, so none of the main wiring has changed (2 switch locations). I've now setup a new bigger battery and DC/DC controller, but LEDs are blowing fuses.

Thoughts?

Thanks

 

[brsnick]

The only wiring that's been added is a 400mm length to increase the length to get the wire to new fusebox location.

 

[Loz]

Thoughts?

Heat shrink

 

[brsnick]

Heat shrink?!?! I have to pay that. It did make me chuckle. All sorted. I had a cable with a knick in it from getting jammed in the column when running it through. Luckily wasn't to hard to find and redo.

 

[Zave]

Direct to the battery is always preferable. However, if this isn't practicle then a good body earth is fine.

I didn't realise this could be done as I heard you need some resistance in the circuit provided by the chassis.

I'm just wiring in my fridge etc now and shall use the battery based on what you've said and that I can't find a convenient chassis point.

 

[Loz]

I didn't realise this could be done as I heard you need some resistance in the circuit provided by the chassis.

Errrr, No !

The reason you need to connect to the chassis, is if you have a battery monitor, you need the current to flow through monitoring device(shunt).

 

[Zave]

Errrr, No !

The reason you need to connect to the chassis, is if you have a battery monitor, you need the current to flow through monitoring device(shunt).

Does the voltmeter on my switch panel count as a monitor?
It's easier for me to connect the negative straight to the battery. If I do need to go via the chassis I believe there is one below the seat so I could try that.

 

[Loz]

Does the voltmeter on my switch panel count as a monitor?
It's easier for me to connect the negative straight to the battery. If I do need to go via the chassis I believe there is one below the seat so I could try that.

Volt meter alone is fine, unless it has a mode to show you how much current is being drawn in Amps.