FJ Cruisers of Northern California
12v wiring question
All, I am very new to 12v electrical and want to make sure I am doing things correctly. Wondering if someone could double check my plan and make sure I am not completely backasswords in my design. I am completely open to criticism. I am attaching a diagram (don't laugh I did it on paint and dont know waht the correct symbols are :-)) but here is the gist of what I am trying to accomplish.
I want to install a 6 station fuse block (blue sea w/ground) that will be always on, but protected by a Low Voltage cutoff switch.
from battery to 50 amp Blue Sea Breaker. This runs to a relay that is controlled by a low voltage cutoff switch. The relay then connects into the Positive side of the fuse box
the diagram hopefully explains it better.
I am planning to purchase the spod as well for all of my switched accessories, but this is for my others.
Any help or guidance would be awsome.
Thanks
Lance
Views: 38
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Replies to This Discussion
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Permalink Reply by ray gates on
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Yeah sounds just like I did one for accessories. Now will do over with sPod....
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Permalink Reply by Sonof40 on
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I think you want the LVCO switch in series with the breaker, not parallel. Otherwise if it activates the breaker will still provide power.
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Permalink Reply by techie on
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Your diagram is correct.
The relay is held closed by the supply voltage through the LVCO.
When the LVCO drops out, the relay follows. The LVCO can be sized to run the relay coil, as the relay handles the actual load. The breaker is simply overcurrent protection. The actual switching is done by the relay.
As an alternative, you could use smaller individual relays on the load side of the fuse block, master controlled by the LVCO, instead of a single large relay. This would give you the option of adding control switches in series between the LVCO and the relay(s) to switch individual circuits. If you use SPDT or DPDT switches, you could provide an override for individual circuits by wiring one side of the switch to the LVCO, the other side to unswitched dc, and the common to the relay. Up=On(LVCO), Center=off, Down=On(override), and put a guarded master switch on the override so it can't be turned on accidentally.
Despite the additional complexity, most of the wiring could be done around the fuse block, with only wiring to the switches, #6 power from the breaker (which should be located as close to the battery as possible), #6 ground, and load wiring having to run elsewhere.
I would protect the LVCO with it's own fuse, but if you use individual relays, you could power it from the fuse block..
Also, you don't need the #6 ground from the relay, since it's only going to handling the relay coil. #18 or #16 should be fine.
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Permalink Reply by PRS TiFJ on
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for your low voltage (should be low current) cut off switch. Just tap one side of your 12v 6 gauge wire and attach it to the positive side of the relay. then run the ground side to your switch and then the other side of the switch to ground. this way the switch just provides the ground to complete the circuit to energize the relay. this will simplify the wiring a bit. you do not need 6 gauge off the relay to ground. this ground is only there for the current draw from the relay coil which will be in the milliamp range. place your relay as close to the battery as possible.
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No need to have individual relays to each circuit unless you want to control them independently. If you just want to be able to turn off the whole circuit then the previous way is much better. Besides having a relay right after the circuit breaker will prevent having power to any of the block when not in use. a bit more safe this way.
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