Hello,

So I've got most of the pieces that I will be building my fuse/relay box out of. Basically a case from polycase, blue sea fuse box, relays, connections... Now my plan was to make the accessories run on switched power since I run doors and roof off through the summer/fall and don't want anyone draining my battery.

Two things that I see I need... a circuit breaker for the line and then a relay. Now the blue sea fuse box says its rated for 100amps. Presently I am going to be using up about 70amps if everything was running at once. Should I still go with a 100amp breaker? Or something closer to 70 amps. I'm sure I'll fill it up eventually but not at the present time.

Is there any other way of running this? Battery -> 100amp breaker -> 100amp relay -> fuse box...

Thanks,

 

Does this factor in peak power vs continuous power? Sometimes when devices start they draw a larger load of power then is needed to run said device. As long as nothing has a peak power above 70A you should be good. Personally I'd keep it closer to 100

Also, why do you want to put a breaker and fuse in the same ckt. Trying to save $ on fuses?

 

Safety? Seems to be the general thought on all the threads I've seen on the forum. Circuit breaker goes by the battery on the line and the fuses are on the fuse block further down in the distribution box. At this point it costs more $$ then less. Breaker essentially protects the line running from the battery to the box. That is the way I understood it.

Not 100% on the peak vs continuous. I went off of what the stickers and then just did the math on the ones that didn't have amps listed. Its mostly LED lights at this point though so I should be okay, I'll go with the 100 to be sure though.

 

This for run-down protection -> Cole Hersee Sure Start Auto Low Voltage Disconnect 1 Each Cole Hersee - SureStart™ Automatic Low Voltage Disconnect Switch [CH-48510] - $125.41 : TheElectricalDepot.com!, Electrical Connectors and Much More!

And this for a system CB -> Amazon.com: Bussmann Hi-Amp Reset Circuit Breaker - 100 Amps: Automotive

 

Now would that in theory work as switched power? For example all the switches work when the key is off but if it turns off power when it gets low and there is still juice left to start... that works no? But then I suppose people can still dick around with the buttons.

 

One way to do it would be to run the power to the relays through the surestart switch. Run the switches themself off of ignition power. The relays in the box would always have power (unless voltage ran low, of course) but the relays wouldn't close the circuit until the coil is energized, which would require power (through your switches) that comes from an ignition source.

 

The box I built is powered from the battery with a circuit breaker between the battery and the box. Each relay is the correct size for the pair of lights it powers and each relay is fused. The switches are powered from a switched power source. They are also daisy chained for the power and ground. There is a in line fuse for the main power wire coming into the switch pod. The relay box I used is also daisy chained for the power and ground. So I have 4 wires going from the cab to the relay box to power each of the 4 relays. Out of the box there is the main power wire to the breaker through to the battery. There is one main ground out of the box. Then 4 wires out of the box that split near the lights, as in one power wire that turns into 2 to power each light in a pair of lights. Each pair of lights ground wires are connected into one wire and grounded near where they are mounted. Hope this makes some kind of sense. Let me know if you have questions or need pics, I can take some in the morning.

 

I believe that makes sense.

So essentially as you both described, the relays and the box are essentially always energized. But the power going into the switch is switched power meaning they wont actually make the relay in the box "turn on".

Would I be able to run 8 switches off of something switched in the dash though? I imagine the switches only pull a couple amps at most, or am I better off making another line from the factory fuse box.

 

Correct, relay box is energized, but without the power to the coil... no juice out of it. Unless you wire the 87a terminal, which will have power whenever the coil is NOT energized, whether the switching power is on or off.

A relay coil pulls about 0.16 amps per relay, so about 1.28 for 8 of them. Figure 2 amps just to be sure. So if you run them off a fuse that is a 10 amps, your fine. of course, that depends what fuse you run them of off. If you run off a 10 amp headlight fuse (for example, not sure what it's rated at), and the headlights draw 9 amps... probably going to blow it if you flip all 8 switches on. Odds are, with such a low draw, you're fine.

 

Sorry, I mis-read the goal. I would just run the box power feed through a suitable relay and trigger the relay with a 12v "run" hot from something in the Jeep. There are plenty to choose from. Something like this -> Heavy Duty 12V DC Relay 100A Automotive Switch | eBay