LED Strip Light addition -- battery power?

I wired our LED light strip straight into the porch light and replaced the bulb in the porch light with an LED bulb. I drilled a small hole into the side of the light to run the wires through. Instead of using wire nuts I soldered the new wires to metal prongs on the back of the socket where the fixture's wires attach. It only took me about 30 minutes including mounting the LED strip under the awning. Works great!

I know that you have three pages of replies and I haven't read all of them but her is a link to a set on eBay. These are not waterproof but they are 12vdc.2amp. I think the one from Amazon is too.

LED STRIP

I have purchased a lot of LED strips and had very good results in making indirect lighting in cabinets and display shelving.

Here is a dimmer with remote control for LEDs.

Dimmer

RandACampin wrote:

tenbear wrote:

RandACampin wrote:
Current is the same in the entire circuit...therefore a fuse anywhere in the circuit will afford the same protection.

"The current is the same in the entire circuit."

That is true in normal operation, but if a short develops in the wire, the current will be very high between the battery and the short. The fuse will only protect the circuit if it is located between the short and the battery. Shorts can happen anywhere that the wire rubs against something, especially the metal frame.

And the fuse will protect it no matter where it is in the circuit. Car fuse panels are nowhere near the battery, RV fuse blocks are often at the other end of the trailer from the battery on the tongue.

Ohms law means that no matter where the short is the current is the same throughout the entire circuit whether the short is at or near the battery the entire conductor (circuit) will see the same rise in current.

I think you're thinking more of Kirchhoff's current law and its corollaries. For a simple loop, the current through any portion of it will be equal (in a DC analysis, at least). Once there's a short, the circuit is no longer a simple loop, but has two sections in parallel, and the current is not equal throughout the circuit.

If the short happens before the fuse, the fuse is not a part of that leg of the circuit, and it does not serve to limit the current by blowing out, and so very bad things happen. (RV circuits may well have many parallel segments by design, too; if there are multiple lights on one circuit, they're wired in parallel, and the current through each light is independent of the others.)

Car fuse panels are fed by one (or possibly more) heavier wires, that go to bigger fuses or fusible links close to the battery. Similarly, on my RV, there's a self-resetting circuit breaker near the battery and a heavy wire from it to the main DC fuse panel, some distance away. The circuit breaker is sized such that it will provide sufficient protection for the heavy wire (it won't let too much current flow so that the wire gets too hot), even though it would be more than the branch circuits could safely handle. The branch circuits from the fuse panel then have their individual fuses, suitably sized for their requirements.

RandACampin wrote:

tenbear wrote:

RandACampin wrote:
Current is the same in the entire circuit...therefore a fuse anywhere in the circuit will afford the same protection.

"The current is the same in the entire circuit."

That is true in normal operation, but if a short develops in the wire, the current will be very high between the battery and the short. The fuse will only protect the circuit if it is located between the short and the battery. Shorts can happen anywhere that the wire rubs against something, especially the metal frame.

And the fuse will protect it no matter where it is in the circuit. Car fuse panels are nowhere near the battery, RV fuse blocks are often at the other end of the trailer from the battery on the tongue.

Ohms law means that no matter where the short is the current is the same throughout the entire circuit whether the short is at or near the battery the entire conductor (circuit) will see the same rise in current.

1. Every single modern-ish car not designed by the British (poke) has a main battery fuse mounted as close to the battery as possible, usually the main fuse block next to it. Example:



The wire leading to this is rated for the total load of the vehicle's electrical system except for the starter (which is generally unprotected). After this, each sub-circuit has a fuse rated for its total load as close to the main battery fuse as possible. This is because any length of wire prior to the fuse it unprotected.

2. Ohm's law specifically states: "the current through a conductor between two points is directly proportional to the potential difference across the two points."

BETWEEN TWO POINTS. So, from point A to B, current will be constant. If the fuse is between A and B, then current generally (fuses/relays can fail) is regulated by the fuse. If the fuse is not between A and B, the current can and will reach whatever it wants until the wire itself becomes a fuse (generally resulting in burning of some sort). A circuit is not a wire. A circuit is the flow of electrons from positive to negative (DC). If the ground is 1/3 of the way down the wire, and the resistance is low enough, the circuit is 1/3 of the wire, plus whatever the shortest path back to the battery is. Anything powered on after that is a different circuit with the same source.

Don't believe me? An experiment (which would be at your own risk) would be to take a fuse holder, connect one end to the positive, and some other point in the wire (stripped bare) before the fuse and touch it to the negative. I'd suggest a good burn ointment, but I know how electricity works. :D

tenbear wrote:

RandACampin wrote:
Current is the same in the entire circuit...therefore a fuse anywhere in the circuit will afford the same protection.

"The current is the same in the entire circuit."

That is true in normal operation, but if a short develops in the wire, the current will be very high between the battery and the short. The fuse will only protect the circuit if it is located between the short and the battery. Shorts can happen anywhere that the wire rubs against something, especially the metal frame.

And the fuse will protect it no matter where it is in the circuit. Car fuse panels are nowhere near the battery, RV fuse blocks are often at the other end of the trailer from the battery on the tongue.

Ohms law means that no matter where the short is the current is the same throughout the entire circuit whether the short is at or near the battery the entire conductor (circuit) will see the same rise in current.

AZDesertRat wrote:
Thinking about doing this to my toyhauler.
Do you buy the RGB LEDs or the white or the RGBW? How do the colors look? Can the combination of the three colors be adjusted so they are close to a white color? And are they dimmable?

Click on my link to the LED string. They are RGB, and the controller lets you choose white, which isn't a true white, more of a bluish white. Yes they are dimmable. Just look at the remote that I posted and it is self explanitory. W for white top 2 buttons on the left control brightness.

RandACampin wrote:
Current is the same in the entire circuit...therefore a fuse anywhere in the circuit will afford the same protection.

"The current is the same in the entire circuit."

That is true in normal operation, but if a short develops in the wire, the current will be very high between the battery and the short. The fuse will only protect the circuit if it is located between the short and the battery. Shorts can happen anywhere that the wire rubs against something, especially the metal frame.

RandACampin wrote:

tenbear wrote:
I'm just a little confused by your post.

First, anything wired directly to the battery must be fused as close to the battery as possible.

Why would you not be able to use the lights when dry camping if wired to some other convenient 12v source? The porch light, or it's switch, comes to mind.

What would the extension cable be for?

If wired directly to the battery it is one more thing to disconnect (turn off) when in storage.

You can put the fuse anywhere in the circuit, makes no difference.

No, it DOES make a difference!!!!

you can put the fuse anywhere you want, however how effective it is depends on placement. since the battery can supply close to 500Amps in a short circuit and the wire for these lights is only capable of handling maybe 10-15A before it gets hot enough to cause a fire hazard, you want the fuse as close to the battery as possible. the fuse won't protect against any short before the fuse. and that's the whole purpose of the fuse.

Thinking about doing this to my toyhauler.
Do you buy the RGB LEDs or the white or the RGBW? How do the colors look? Can the combination of the three colors be adjusted so they are close to a white color? And are they dimmable?

DrewE wrote:

RandACampin wrote:

tenbear wrote:
I'm just a little confused by your post.

First, anything wired directly to the battery must be fused as close to the battery as possible.

Why would you not be able to use the lights when dry camping if wired to some other convenient 12v source? The porch light, or it's switch, comes to mind.

What would the extension cable be for?

If wired directly to the battery it is one more thing to disconnect (turn off) when in storage.

You can put the fuse anywhere in the circuit, makes no difference.

If wired into the existing porch light circuit, there is already a fuse.

In general, though, you should put the fuse as close to the power source as practical because the main purposes of the fuse is to prevent the wire run from being overloaded to the point of causing a fire in the event of a short circuit or other overload. The short circuit might not occur at the point the power is used, but could be due to damage to the wiring between the two. If the damage is before the fuse, and the wire shorts to the chassis of the RV, there's nothing limiting the current to safe levels.

Current is the same in the entire circuit...therefore a fuse anywhere in the circuit will afford the same protection.