Fuse or Circuit? Neither?

[Henri3]

I am having trouble when turning on my docking lights, tower light bar nav lights and interior leds, when I turn these on everything goes dead before I get them all on, any ideas, the boat still starts and runs but I lose the radio and all lighting.

[MLA]

Which are factory and which have been added? Those that were added, where are they drawing B+ and B- from? Are fuses blowing or breakers tripping?

[Henri3]

The only ones I have added are the led's, I did change the bulbs on my docking lights but dont think that is the problem. I had tripped a breaker before so I thought thats what is was again this time but I checked them and they were fine. For power for the led's, I ran a control box from the battery around under the steering wheel where I wired all the led's into, so as long as the battery in the boat is charged the led's turn on, to turn the led's on I just have to push in a button on the control box for each set of lights.

[Henri3]

Would it make sense to wire it into my courtesy lights? So in order to turn my led's on I would have to have the courtesy switch on and get rid of the wires all the way around to the battery?

[David Analog]

Incandescent bulbs tend to continue to dim as the voltage is reduced. LEDs tend to shut off completely below a certain voltage threshold.
Tower light bars and docking lights can draw a ton of current, especially halogens, like 5 amps per light for example. You should have a minimum of a 14-gauge two-conductor harness for every three lights. You should not have more than three lights directly off a true 15 amp marine switch.
Any wire, switch, relay, connection, termination, etc. beyond the light itself, that is getting hot is a bad sign and must be remedied.
Use a multimeter to measure the voltage across the +/- leads directly at the light device while under load, especially as you turn additional lights on and off. If you have an inadequate circuit in any way (whether grounding, switch, wire, connections, or terminations) this will be revealed as a voltage drop. This cuts right to the chase and saves time and speculation when diagnosing the problem. In contrast, measuring a circuit's DC resistance is deceiving since you are only measuring with next to no current.

[MLA]

If they all work normally when turned on individually, then I think the problem is going to be traced back to a common B+ or B- point that they all share. I think if you put a digital volt meter on the circuit, and start turning lights on, you will see the voltage begin to drop off. Again, this problem can be either the battery positive side that the lights all share or the battery negative of the circuit.

[David Analog]

Along with what Mike wrote above,

A boat will often start with only 10 volts. Solid state electronics and lighting can be more voltage sensitive.

I wonder if the alternator/starter feed is connected to a different battery than the other electronics as you have it wired currently or as you have things selected. Circumventing the battery switch and going battery-direct on some accessories could be problematic. There could be a difference in terminations, grounds or recharging of the two batteries.

Take just one circuit off line at a time and test. If one of these problem circuits has an inadequate ground or a moderate short, it can siphon voltage from the other DC circuits in parallel causing a voltage drop. Also, a B+ supply, with a number of low resistance DC bulbs in parallel can measure like a ground, especially with a test light, while that particular circuit is off. So check each assumed ground for what it shouldn’t be (DC voltage) before confirming what it should be. Don’t forget to turn a dash light dimmer rheostat to full before testing.

[Henri3]

OK, I didn't have any problems with it until I put the led's in, which are routed directly to the battery, so in your post above with going battery direct could be problematic, if I wire them in to a different switch do you think this would fix my problem?

[David Analog]

OK, I didn't have any problems with it until I put the led's in, which are routed directly to the battery, so in your post above with going battery direct could be problematic, if I wire them in to a different switch do you think this would fix my problem?

I don't know. The LED circuit shouldn't be connected to the others in any manner and in-boat LED lighting typical draws a VERY small current. Btw, each and every lighting circuit should have the appropriate size of fusing. You are just going to have to make those tests isolating each element one by one. Don't get locked into over-learning coincidences. The timing may or may not be related. Make the tests and get a multimeter (only $10+). You only need to learn a couple of the most basic meter functions to diagnose just about anything.

[Henri3]

Ok thanks for the help!