A better fusebox

[FridgeFreezer]

Probably not what Dan had in mind for the "Special Projects" forum but I thought it kinda fitted the description.

As I've found myself wiring various vehicles over the years, it's always struck me that the available fuseboxes are never quite right - they don't hold enough fuses, or they are a pain to mount, or they are huge, or it's not easy to get power in to all of the circuits, etc. etc.

So, while waiting for my code to compile, I had a go with the crayons and knocked up something to see how it turned out.

Built up with some fuses fitted:

Added feature - fuse blown LED indicators:

I went a bit OTT with it really - the footprints for the connections allow for blade terminals facing up, or at 90degrees as seen here, or wires soldered in. The main connection is 6mm or 8mm screws/bolts for ring terminals (or solder in a fat cable I suppose) with more spade/wire terminal holes if required. All the fuses are bussed from the main feed.

Interestingly, while testing to see if it would handle the current, I discovered that one of the 30A fuses was getting quite warm at ~20A. Investigation revealed that the fuse was dropping about 0.2v across it! Swapping for a different 30A fuse (presumably a better made one) knocked this on the head and the drop went down by a factor of ten.

One minor restriction is you can't run loads of amps through it, the back of the envelope suggests perhaps 80A max in total, although aside from an electric fan or two there's not much on a car that will be drawing more than 10A all the time, so overall it should be more than happy unless you run 12 pairs of spotlights off it all at once (I know there are some people...)

I was aiming to get it smaller than the 12-way bussed Marine fuseboxes (165mm x 95mm x 57mm) that are the best solution I've found so far, the overall size is 100mm x 90mm, and allowing for 6mm spacers underneath it's 28mm tall. I could shave some off but I wasn't sure of how accessible the fuses/connections would be so I erred on the large side. 2nd time round I may compact it all, or add more fuses.

What do people think? Will I sell a million?

[CwazyWabbit]

Have you found a case that it fits nicely into?

Out of curiosity where do you get your PCB's made?

[Bowie69]

Very, very nice work Fridge, 80A I would think it plenty for most accessories, as long as you are sensible about it and don't try and run too much off one fuseboard at the same time.

Just need a 12-way busbar for the grounds and very tidy.

Are you thinking of marketing them ?

Got an idea for a relay block as well?

[FridgeFreezer]

Haven't found a case, haven't looked - the basic idea was to just mount it with spacers / washers. Very hard to put a fusebox inside a box and then get all the wires in/out neatly unless it's a much bigger box anyway.

PCB house was iteadstudio, in this size the bare boards come out at $25 for 10. Drawback is you don't get to chose the quality (thicker copper would be nice, but not essential) but by crikey are they cheap and surprisingly good.

I figure a ground bus-bar or commoning block etc. is easy enough as it doesn't (usually) have to be insulated from its mountings, so can just be a bit of bar with holes drilled. I was thinking about mimicking the marine one with power + ground but it wouldn't have worked in the space available with reasonable current carrying. If the need / demand arises it's always a possibility though!

I wasn't particularly planning on marketing them per se, the PCB minimum batch was 10 units, if I build them up & post them I'd guess they'd come out about £25 a unit allowing for a beer's profit so I don't know if that makes them of interest compared to what's out there already.

A relay board of some description is in my plans, although the boss has just knocked out a very nifty multi-purpose smart relay PCB that could prove very useful indeed. This post may spur him to post it up, you never know.

[TSD]

Not much of a boss obviously, since the software department is turning out PCBs instead of working but I probably only have myself to blame

The smart relay mentioned is a bit of a pet project of mine. It's a 10A relay combined with a hugely overspecced microcontroller, and is pretty much a device looking for a job.

I had a couple of tasks in mind, so set about making a relay board as multipurpose as possible.

It can measure ambient temperature with reasonable accuracy, and voltage on all its inputs with good accuracy. It also has a decent timer, and only draws around 1mA when idle.

A 16 position switch allows it to be tuned or adjusted without changing the software. (There are a few other inputs and outputs designed in to combat mission creep.)

It fits into a 30 x 40 x 50mm potting box, with just the flag terminals and switch body sticking out.

It's slated for a few jobs around my various trucks -

1. Automatically disconnect the fridge from permanent live feed several hours after engine off.

2. Replace the usual Rover VSR with a smarter version that doesn't switch in the auxiliary battery until 15 mins after engine start, to allow the starter battery to get a headstart. Also prevent switch 'chatter' when the aux battery is flat and the engine is idling.

3. Replace the 'oval' webasto timer and control a Webasto Thermotop V via wbus, which can be troublesome.

4. It would be monumental overkill, but it could be used as the inverter circuit for using the Range Rover coolant level sensor with a dashboard warning light, with lamp test, anti false alarm delay etc.

Nothing groundbreaking, but a bit of fun for me. Parts cost is pretty low, but the soldering needs a steady hand and it isn't much fun building lots of them. Think I've built five of them so far, that should keep me going for a while.

[Team Idris]

Fuse board is a comercial likely

No earth needed, you have a 5mm bolt next to it as an earth stud. No box either, as like you say, it makes it huge. Sell it as a self-solder kit, as it is mega cool to have warning LED's

I like the controller relay a lot. I run my robot fish on the Oopic which was a mare to program, so I hope this one is a lot easier.

Love the 16 bit 'selector'. Could it be sold as a knock-down kit? That would be the decider.......

Like my drop-pin-fairleads, you don't really know untill you have a dabble

Somtimes I think we should make better use of the lego mindstorm. Simple drag and drop programing and loads of sensors. But I digress

[simonr]

I really like this Fridge! The LED warnings are the best bit - you could sell these as for competition use - "Find electrical faults in seconds!"

What about putting the flag terminals on the reverse of the board then have a plastic / metal screen / panel, laser cut such that the fuse bodies poke through & you can see the LED's through holes.

Good work John!

Si

[TSD]

I like the controller relay a lot. I run my robot fish on the Oopic which was a mare to program, so I hope this one is a lot easier.

Love the 16 bit 'selector'. Could it be sold as a knock-down kit? That would be the decider.......

Programming is easy enough, if you like C (which I don't)

My thought was if it ever became a 'product' then it would be the same hardware, with one of a small range of firmware preloaded and not reprogrammable in the field.

So with the standard firmware you'd choose between 4 delayed ON times, 4 delayed OFF times, 4 different VSR switch voltages and 4 'something else'. The biggest

problem is working out exactly what the 16 basic options would be.

I don't think it would work as a kit because most people can't solder SMD components. In small quantities, and allowing Fridges 'a pints worth' of profit margin, they could probably go out the door for £30 a time, so there isn't really any money worth saving in breaking it down smaller.

One option might be to replace the relay with a solid state switch to drive an external relay - doesn't save any money, but does make the unit a lot smaller in height, which would save a load of potting compound! The downside is the need to use an extra relay most of the time, and there's only one way to wire it up vs. having a pair of relay contacts you can use how you like.

[Bowie69]

I suppose this is a similar item: http://www.ebay.co.uk/itm/10-Way-Blade-Fuse-Box-Positive-Bus-in-12v-LED-WARNING-Kit-Car-Boat-Marine-Trike-/180817893827

Not PCB based, and only 100A max per box, so very similar spec, but who knows what the quality is like with anything on Ebay...

[simonr]

There are a number of kits where the SMD's are flow soldered to a board but the discretes are soldered by the user.

Another option is to use something like an ATTiny which is available as an 8 Pin DIL - so easy to solder / socket and there are free BASIC compilers - for easy programming by non C fluent people. Supply it with basic common functions, but with the ability to reprogram if required.

I would build it on the underside of a relay socket with the relay spades duplicated on the other side of the board plus the input terminals sticking out the side. That way, you can plug it in to a regular (automotive) relay socket for power / switching connections. Use the original coil connections as one input (through a Diode OR so it doesn't matter which way they are connected) and have separate power connections on the side via through plated holes.

That way, the footprint is only slightly larger than a relay. The controller is cheap enough to be permanently embedded.

The initial firmware is selected by bridging inputs to GND rather than with a switch.

Useful functions include:

Voltage Sensitive Switch

VSS with delay (as you suggested)

One Shot timer using a variable resistor. +ve and -ve edge triggered

AND, NAND, OR, NOR, XOR boolean functions.

Flasher with rate set with VR

Flip-Flop (alternate between On / Off when an input is pulsed)

Regular Relay with Enable input.

Buzzer (by switching coil on/of fast) - it could even play tunes!

Programmable Wiper controller. Measure the separation of two wipes from the column stalk - and repeat with the same duration. If the separation exceeds 30 sec, switch off.

Glow plug timer.

Light sequencer (by connecting more than one relay together) for emergency vehicles to flash the head lights / main beam.

Simple Pulse counting Alarm. Connect several sensors to one input. Relay contacts 'flash' if say 3 triggers detected within 30 sec. Connect in line with horn - so horn operates normally. Enabled / Disabled with another input.

'Tracker' - same as alarm but double flash / alternate the brake lights. The Police will almost certainly follow it when seen!

This sounds like a good KickStarter project!

Si

[simonr]

Fridge. For the LED fuse thing, what about making a fuse holder with the fuse spades duplicated on the other side with an LED / Resistor on the board.

I know you can buy fuses with LED's but they are about 100x the price of a fuse on it's own. This would let you use any old fuse.

It has the advantage that you can easily reverse the holder if the current flow is in the wrong direction - and you can test it by unplugging the fuse from the board when the board is in situ. This would retro-fit to any vehicle with blade fuses.

Si

[TSD]

There are only 7 discretes, hardly seems worth the effort to separate it out for small quantities, though if I was sending out 100 boards for assembly I would think differently.

You're right, there are plenty of easier ways to program a micro, and plenty of micros to choose from. If I had been designing something to be used by someone else I might have used something different.

I was originally going to make the PCB with a standard relay footprint, but that was killed off by putting a 'real' relay with a decent spec on the board. Not impossible though, just makes it a little more complex to assemble, probably using two PCBs.

Might be worth looking for a source of automotive relay sized cases (with a mounting flange ideally), which would make the idea more attractive.

Flip-Flop (alternate between On / Off when an input is pulsed)

I like that in particular - it's something Fridge already suggested for using push-on, push-off dashboard switches.

[FridgeFreezer]

What about putting the flag terminals on the reverse of the board then have a plastic / metal screen / panel, laser cut such that the fuse bodies poke through & you can see the LED's through holes.

Well, it's possible to solder the flags either side, or put "straight up" ones on either side. Laser-cutting a mount / insulator from acrylic had crossed my mind but I don't have a laser cutter or any acrylic... if someone wants to order a batch they can have whatever they like

Fridge. For the LED fuse thing, what about making a fuse holder with the fuse spades duplicated on the other side with an LED / Resistor on the board.

A bag of 3mm 12v LED's poked into the fuse holder from behind works for that with no PCB, my main gripe was with inconveniently designed fuse-holders, the indicators were an easy/cheap add to the board.

[simonr]

A bag of LED's doesn't make as good a product! An easy to fit, proper looking thing does - and is something you could sell. Likewise with the fuse board - something (a panel / case) that costs little if you order a few can make a big difference to the perceived value.

I guess that's the difference between a project & a product with most things. A project you can sell to geeks (I include myself in this). A product you can sell to anybody else. A hackable (customisable) product you can sell to everybody, including the geeks.

By the way - I like your little 'Flying Spanners' logo in the middle of the board!

Si

[simonr]

I like that in particular - it's something Fridge already suggested for using push-on, push-off dashboard switches.

Add an Enable input and you can use it for things like Fog lights which only come on with headlights.

Si

[94Discovery]

A bag of LED's doesn't make as good a product! An easy to fit, proper looking thing does - and is something you could sell. Likewise with the fuse board - something (a panel / case) that costs little if you order a few can make a big difference to the perceived value.

I guess that's the difference between a project & a product with most things. A project you can sell to geeks (I include myself in this). A product you can sell to anybody else. A hackable (customisable) product you can sell to everybody, including the geeks.

By the way - I like your little 'Flying Spanners' logo in the middle of the board!

Si

i like your reasoning ,and lets devid the thread into 2 things .

Geek gadjets ( you and TSD)

And K I S S (FF)

While Geek can desingn a microcontroler that can do what ever you dream of .

And KISS can design a board with multi relays and fuses that can be controled by switches or the Geek microcontrller this way people can upgrade there parts as a modular design .

Lets make a pole of what people wand need and after the 2 teams can develope somthing that can be a product.

Thank you

Naji M.

[C18RCH]

I keep toying with the idea of fitting a CB panel like this one to replace the fuse box:

http://www.ebay.co.uk/itm/12V-8-Gang-Black-Wave-Design-Switch-Panel-Circuit-Breakers-10028BK-Boat-Marine-/140870303967?pt=UK_CarsParts_Vehicles_BoatEquipment_Accessories_SM&hash=item20cc8640df#ht_895wt_934

Quite an expensive solution given how inexpensive fuses (especially for the higher current CBs) are but for expedition/competition use it would give you the same quick fault finding and no need to carry spare fuses.

Has anyone tried this before?

[Tanuki]

Must admit, I much prefer the CB panel approach: apart from the "no need to carry spare fuses" issue it's also possible to choose CBs that better match the expected currents on a circuit.

Motors/bulbs typically have a high start-up surge current - sometimes 10x the average current they take. So to prevent fuses blowing you either need to rather over-rate them or - after a period - the repeated surges will thermally-fatigue the fuses and they'll then choose to fail at the maximally-inconvenient moment.

CBs as well as having a trip-current have an overcurrent/time profile - this can be tailored to match the expected load.

So a typical 60-watt 12V headlamp bulb - which should take 5 amps - ideally needs something like a 6-amp-continuous rated protection device - it could be fitted with a 6-amp breaker that was rated to allow a 25-amp surge for 0.5 of a second without tripping.

You can't do that with blade-fuses (or at least I've never come across them in slow- and quick-blow varieties).

[TSD]

As far as I know all ATO fuses (standard size blades as we know them) are all described as Fast Blow, with nominal 0.5 second interruption at 200% rated load.

They are intended to be fed from upstream protection using maxi sized fuses, which are slow blowing.

You can buy good quality circuit breakers in ATO fuse sizes, not suprisingly they have (I^2)t parameters (blow time vs current) similar to the fuses they replace.

ETA make good ones for £10-£15 per position. You can get cheaper no-name ones, but if you're going to skimp, just fit decent fuses instead

If you were properly specifying a breaker for a 5 A headlamp bulb, you'd expect to use at least a 10A breaker to eliminate 'nuisance' trips.

(Ambient temperature, mounting type, even the size of the connecting wires can and do affect fuse blow characteristics)

If you used a 10A ATO fuse for the suggested task, then it would carry your 25 amp surge for a little more than 0.5s but less than 1 second before interruption.

[henk]

i like the idea but I miss relays. I am looking for years now to find a decent solution to switch on lights etc, found the fusebox from blue ocean very usefull but there is no box on the market with fuses and relays

[Inigo]

There is a Bussman waterproof fuse and relay box, detailed on the ih8mud forum but only available in the states. I ordered a couple together with assorted connectors to have a play with. Not yet got around to seeing if it all goes together well though.

[henk]

This one? http://forum.ih8mud.com/merchandise-storefront/352802-auxiliary-fuse-relay-panel.html#post5240849

[Inigo]

That's the one.

I couldn't see that the chap who put it all together was selling a complete system anymore, so I managed to order a couple of boxes, a handful of relays and bucketload of connectors and seals from Waytekwire and get it shipped via reship.

The vehicle I had planned to use these on is off the road for the moment, but I have a replacement! Just got to find somewhere to site the fusebox and then I'll have a play.

[Inigo]

Just checked that thread and it seems he is making them again now. Price is more or less what I paid for the parts.