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12V Clarification / Question
- Thread starter cg25713
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No. If you have a 4 speed tranny you should be all set with what is on your rig.
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You can get away with wiring things straight to the rear battery as long as the amount of load doesn't get too high.
For the older trucks with a 60 amp generator you'd definitely want a converter due to imbalance, but the 200 amp is a 24/12 output, and provides up to 50 amps of charging to the rear battery at 12V. Part of that is being used by the transmission control computer, so don't put more than about 30-40 amps of load on the rear battery. More than that and you really will want a converter.
For the older trucks with a 60 amp generator you'd definitely want a converter due to imbalance, but the 200 amp is a 24/12 output, and provides up to 50 amps of charging to the rear battery at 12V. Part of that is being used by the transmission control computer, so don't put more than about 30-40 amps of load on the rear battery. More than that and you really will want a converter.
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if you plan to use it a lot with the engine off then the converter is also a better idea to keep from running down the rear battery, but if your batteries are in good shape and you aren't running the stereo full blast for hours on end or leaving the dome light on for days at a time it shouldn't be an issue
So I could connect the fuse block below directly to the rear battery pos and neg and run a stereo, light etc. from that as long as the amp draw is relatively low?
If yes, what gauge wire would you suggest I use? I plan to mount the fuse block in the small space next to the battery compartment. Thank you.
If yes, what gauge wire would you suggest I use? I plan to mount the fuse block in the small space next to the battery compartment. Thank you.
Action
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I know some HMMWV have the fording kit, but I have never seen a fish finder in one !
or depth sounder or auto-pilot, either.
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I didn’t know my spare tire needed two fuses.
papakb
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To answer your question I would use 8 AWG wire at the minimum to the fuse block and 4 gauge if you plan on installing anything that draws more then 20 amps.
BTW, that depth sounder fuse could be used for an oil level sensor!
BTW, that depth sounder fuse could be used for an oil level sensor!
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What wire size you run depends on what you are planning to power/how much draw. That also determines what size fuse.
Simple wire chart here:
For automotive applications, 14 gauge is usually good for 15 amps, 12 gauge for 20 amps, 10 gauge for 30 amps. I like to just run the Prestolite 14 gauge military cable for anything needing 15 amps or less. (keep in mind these are shorter runs, for longer lengths you need to go up in size)
You can always run a larger wire (smaller number size) than you need, but you never run a smaller one. Same goes for fuses. You can run any size fuse with a lower rating than the wire is good for safely.
For the above fuse block, the manufacturer rates it for 100 amps in and max 30 per circuit, so it depends on how far away from the battery it is for what size wire, as you want to keep the amount of voltage lost through the wires to a minimum (usually 2% or less). According to the chart I linked above, you would want minimum of 8 gauge wire to the fuse block if under 7 feet wire, and 6 or 4 if more than that. Remember also that's 7 feet total wire, which means 3.5 feet of positive wire and 3.5 feet of negative wire, not 7 feet of each.
As most circuits will end up grounding to the chassis or body, you only have to count the wire length to get to the grounding point, not all the way back to the battery (unless you're grounding everything to the battery negative terminal)
specs for the above fuse block:
www.bluesea.com
Simple wire chart here:
For automotive applications, 14 gauge is usually good for 15 amps, 12 gauge for 20 amps, 10 gauge for 30 amps. I like to just run the Prestolite 14 gauge military cable for anything needing 15 amps or less. (keep in mind these are shorter runs, for longer lengths you need to go up in size)
You can always run a larger wire (smaller number size) than you need, but you never run a smaller one. Same goes for fuses. You can run any size fuse with a lower rating than the wire is good for safely.
For the above fuse block, the manufacturer rates it for 100 amps in and max 30 per circuit, so it depends on how far away from the battery it is for what size wire, as you want to keep the amount of voltage lost through the wires to a minimum (usually 2% or less). According to the chart I linked above, you would want minimum of 8 gauge wire to the fuse block if under 7 feet wire, and 6 or 4 if more than that. Remember also that's 7 feet total wire, which means 3.5 feet of positive wire and 3.5 feet of negative wire, not 7 feet of each.
As most circuits will end up grounding to the chassis or body, you only have to count the wire length to get to the grounding point, not all the way back to the battery (unless you're grounding everything to the battery negative terminal)
specs for the above fuse block:
ST Blade Fuse Block - 6 Circuits with Cover - Blue Sea Systems
Compact ATO® / ATC® fuse block consolidates branch circuits and eliminates the tangle of in-line fuses for electronics and other appliances.
www.bluesea.com