12v for the Minimalist Weekender

[DoctahDeane]

Incidentally, reading through the thread, your understanding of basic electricity appears to be pretty sound.

Tom (retired EE)

Well on that kind note, I guess I ought to take the rest of the day off. Thanks to you both.

[DoctahDeane]

As I look at shut off switches I have seen instructions that run the cable from the switch to the positive battery terminal and others that run to the negative battery post. Seems to me that if you want to shut power down completely, that cutting the "hot" side - therefore, the positive connection - makes the most sense. Is this the wisest approach?

[fishboat]

I've been using this breaker-switch for the last year..seems to work very well so far.

https://www.amazon.com/gp/product/B07FL ... =UTF8&th=1


It's installed on the positive cable just off the battery and before the distribution panel. The breaker, and cable to & from, needs to be sized for your system..total draw.

[DoctahDeane]

I've been using this breaker-switch for the last year..seems to work very well so far.

https://www.amazon.com/gp/product/B07FL ... =UTF8&th=1


It's installed on the positive cable just off the battery and before the distribution panel. The breaker, and cable to & from, needs to be sized for your system..total draw.

Awesome, thank you!

[GTS225]

As I look at shut off switches I have seen instructions that run the cable from the switch to the positive battery terminal and others that run to the negative battery post. Seems to me that if you want to shut power down completely, that cutting the "hot" side - therefore, the positive connection - makes the most sense. Is this the wisest approach?

Actually, it'll work either way, as long as the battery/primary power supply is isolated from the rest of the circuits. For race cars, NHRA requires a master shut-off when moving the battery to the trunk area. There is no requirement for which side it gets installed in.
Modern cars, many of the circuits have a fused 12v+ to the load, and the computer switches the 12v-, as the computers REALLY like their grounding.
The idea of switching only the "hot" lead is, I think, a carry-over from 120VAC wiring practices, which is NFPA/NEC standard for house wiring. (In AC wiring, the "hot" is an ungrounded conductor, while the neutral is a grounded conductor, thus limiting the potential voltage in the neutral conductor.)

Roger

[DoctahDeane]

Hi folks -

http://www.aaignition.com/products/prod ... isconnect/?

I got this switch and I have it wired up as a test, before final installation and it works fine. Question is about wire gauge. Without the kill switch in place the negative wire that runs from the negative terminal shunt (shunt is for the battery meter) to the fusebox - is maybe 12 gauge at biggest, probably 14GA. The posts on the kill switch are pretty big and so for the moment, I jury rigged 14GA wire to/from just to confirm it all works.

Considering that the wires in place were not battery cable thickness, AND on the negative side AND that all my positive terminal stuff is appropriate fused...can I go with 12GA wire on the negative side to/from the kill switch? Seems like it should be OK, I don't have any big energy hogs like AC or a COPD - nothing like that, just lights (LED) and USB ports.

Sure did feel good to see battery monitor current readout drop to 0.00 when I hit the kill switch!

[bdosborn]

In the real world we would add up all the loads in the trailer, assume they are all on and add 25% to size the main wires. That being said, I use a #8 and a 30A fuse to run everything but the inverter in my trailer.

Bruce

[DoctahDeane]

In the real world we would add up all the loads in the trailer, assume they are all on and add 25% to size the main wires. That being said, I use a #8 and a 30A fuse to run everything but the inverter in my trailer.

Bruce

Yeah seems much safer = peace of mind. Thanks, Bruce. I was just trying too get off the hook with stuff I have lying around the house.

[DoctahDeane]

Big thanks out to Bruce and Tony - thank you guys (and anyone else who weighed in). Kill switch in and working like a charm with 8GA wire. Battery monitor shows zero drain. Yahoo! I drilled out one of the lower 1/2" drains on the water tank and have a valve but discovered I need a short nipple to allow the valve to turn into place but that'll be it for this season and hoping to have some good late summer/fall adventures. This forum has helped me so much - what a resource! Take care all.