Connecting Farkles -- what is that thing at that end of the cord?

[Michael_T]

What prevents me from just cutting off the "cigarette plug-in" end of a cord and connect the wires to an aux fuse box.

 

Is there something inside the plug other than a fuse, ie, some resistor?

 

Like to know before I make the cut.

 

Michael

[johnlt]

Normally you can just cut it and connect to a fuse block. Make sure the polarity is correct. I have seen some cigarette lighter plugs that have a small voltage reduction circuit in them but normally they don't. Usually you can unscrew the plug and take a look inside. Also, if you can get to the wires on the other end, you can check voltage when plugged in and if it is ~12V, you're good.

[Gregori]

In MOST cases, it's just a fuse inside.

 

But some gizmos require something other than 12 Volts, and the plug will contain the electronics to provide the right power. I had an old Garmin GPS that needed 5 Volts - the plug didn't look much different from a normal one, but had the transformer inside.

 

Try unscrewing the end of the plug. Many times the cap that surrounds the positive contact will simply unscrew or otherwise remove easily. Take a look inside - if it's just wires and a fuse, cut the cord. If it's got a circuit board or the like, then you're more or less stuck with it.

I've modified those complex ones as well, removing the plug housing, attaching a hard-wired pigtail, then wrapping the 'guts' in water-resistant heatshrink, but it's kind of a pain.

(Okay - it's a serious pain - and it's a one-way trip. Restoring said gizmo power cord back to stock requires more effort than it's worth....)

[NoHeat]

In MOST cases, it's just a fuse inside.

 

I doubt if there's a fuse inside unless you could see it. Nobody would manufacture something with a non-serviceable fuse hidden within it. What would that accomplish? If an inaccessible hidden fuse blew the consumer would only be able to detect that the product no longer worked.

 

Fuses exist either to protect the product or to protect the wiring to the product from overheating and causing a fire.

 

If a product requires a fuse, it should be accessible.

 

If there's not an obvious removable fuse or a reset-button for a circuit breaker, then there's probably there's no such thing inside.

[bobbybob]

What prevents me from just cutting off the "cigarette plug-in" end of a cord and connect the wires to an aux fuse box.

 

Is there something inside the plug other than a fuse, ie, some resistor?

 

Like to know before I make the cut.

 

Michael

 

 

Can't believe nobody's asking this: WHAT cord? What does it go to? Is it just an extension cord for a lighter socket? Or the cord to a "known" gizmo like a GPS/etc. ? ?????

[Ken H.]

I doubt if there's a fuse inside unless you could see it. Nobody would manufacture something with a non-serviceable fuse hidden within it. there's probably there's no such thing inside.

Actually... Many of them have a fuse inside. You screw off the tip; and it, and its spring, and the fuse, fall on the floor and roll off somewhere unknown or totally inaccessible...

[eddd]

In MOST cases, it's just a fuse inside.

 

I doubt if there's a fuse inside unless you could see it. Nobody would manufacture something with a non-serviceable fuse hidden within it. What would that accomplish? If an inaccessible hidden fuse blew the consumer would only be able to detect that the product no longer worked.

 

Fuses exist either to protect the product or to protect the wiring to the product from overheating and causing a fire.

 

If a product requires a fuse, it should be accessible.

 

If there's not an obvious removable fuse or a reset-button for a circuit breaker, then there's probably there's no such thing inside.

 

Cigarette lighter-type plugs can have a fuse inside the center tip. You can usually tell because there will be notches on the black portion and ears on the center tip. To access the fuse, push in and twist.

 

 

Ken, you type too fast...or I type too slow.

[Quinn]

Can I assume that you've looked on both ends of the cable and the gizmo to see it the power output is listed? There may be printing of voltage and milliamps on it. If it's a mini-USB then it steps down to 5VDC for sure.

 

---

 

 

[Gregori]

Fuses exist either to protect the product or to protect the wiring to the product from overheating and causing a fire.

 

It is a very common misconception that fuses are for the protection of the fused device. Fuses are used to protect the system (supply wiring) NOT the device. If you want something to protect the device, you'd need a surge protector. More useful in a vehicle system is a diode set - to prevent reverse current from damaging sensitive electronics. (Reverse current generally happens when a high-draw load (like your starter) is used (or during jump starting) and the battery isn't quite up to the task.) See http://www.sto-p.com/pfp/pfp-reversepolarity.htm

 

A device (load) will never draw more than it's designed for - unless it is failing.

There's essentially no way to force more current through a load. But a load can demand more power than the system is prepared to provide, and that's where damage occurs, and is the reason for fuses.

A fuse won't protect from over-voltage (which is supply side failure) only from overcurrent (which is load side failure.)

 

So if you hook up a huge, tractor trailer 12v battery to your ValentineOne, it'll draw the same half amp of power as if you hooked it up to 8 AAA batteries. (But it would run for months on the 100 Lb battery, and less than a day or so on the AAA batteries.)

 

If, however, you hooked up a pair of 100W driving lamps to the same 20 (22?) gauge wire that the V1 uses, you'd melt the insulation off the wires in a flash (so to speak) and potentially cause a fire, damaging or destroying the host vehicle.

 

As an over-simplification: in a properly designed system, the fuse size is determined by the wire size (gauge) - not the anticipated load.

The wire size, in turn, is determined by the anticipated load.

(Actually, both fuse and wire size are both dictated by expected load, length of the run, temp range and other environmental factors, but that's far more complex to explain.)

 

In short ( ) you can practically never run too big a wire, but it's easy to put in too big a fuse.