Wiring Questions..

[disorderly]

Hi I am just trying to put together a wiring diagram and figure out what I need so I am ready to go when my 6.5LOA Centrecab arrives...

Just a couple of questions for those electrically minded folk out there...

1..What size circuit breaker leaving the battery switch in the 6mm cable do I need ..I'll just have basic electronics plus fans, an Engle ,lights etc..

2..Should I bring that 6mm cable to a distribution stud or larger bus bar first behind the helm or just to a switchboard or fusebox...I will have a couple of switchpanels ,fusebox, lighter/usb switchs etc...….

and if so what size stud/bar do I need ……?...

3..In behind my helm electrics panel should I use a buss bar for both negative as well as positive wires or just a negative and the positives going straight into fusebox or switchboard..?

4..What size busbars are recommended for my application up the front and also down the back where I will hook up my bilge pump and deckwash switch..?

5..Any battery terminal fitting better than the others..?

TIA

cheers Scott

[scottar]

1. Automotive 6mm twin sheath cable is rated at 38 amps. I would normally fit a 30 amp fuse or breaker as protection. If this isn't enough for your electrical load, either run two mains and split your load or increase your cable size. Are you setting the system up with a dedicated house battery so as to protect your start battery from being drawn down by the fridge and other accessories or are you going to manage this manually?

2. Totally up to you. More than one way to "skin the proverbial cat". Personally, I prefer to use the fuse panels with a built in negative buss. I usually cut out any in line fuses in accessory cables if practical so all fuses are in the one spot if there is a problem. These panels are available in 6 and 12 circuit configurations. If twelve isn't enough - fit two panels. If you do decide to fit a busbar, it can only supply as much current as your circuit breaker will allow so even a 6mm stud would be ample.

3. If you get the fuse panels with the inbuilt negative bus, there will be no need for any additional busbars. The main runs to the fuse panel. The wire for any accessory then runs from the fuse panel to the relevant switch if there is one and then to the device. The negative for the device goes to the negative bus on the fuse panel.

4. You don't need busbars down the back. The most you may require is a second fuse for the bilge pump if you decide to run a 24 hour circuit (direct off the battery - not through the battery switch) via a float switch as well as the manual switch.

5. Get batteries with posts and use a good quality ring terminal that is crimped properly. Personally I also solder and then dual wall heatshrink. Opinions vary on the solder but I've never had an issue and IMO "if it ain't broke ……"

[disorderly]

Thanks for the detailed reply Scott...much appreciated...

I ordered a blue sea fuse block with negative bus but i also have a fused rocker panel switchboard so was thinking of a seperate negative bus for that...

yep I will have a house battery …..so should I also install a VSR...?

I have never had a 2nd battery before so I'm undecided on what to look for should I be looking at deep cycle , crank battery or a combination of both..?

[Dignity]

Thanks for the detailed reply Scott...much appreciated...

I ordered a blue sea fuse block with negative bus but i also have a fused rocker panel switchboard so was thinking of a seperate negative bus for that...

yep I will have a house battery …..so should I also install a VSR...?

I have never had a 2nd battery before so I'm undecided on what to look for should I be looking at deep cycle , crank battery or a combination of both..?

Scott, I run a second "house battery", it is an AGM deep cycle and it runs all the lighting and electronics. The crank battery only has the motor, trim tabs and the electric winch on it as deep cycles don't like crank loads. The other Scott'ar' alerted .me about a year ago that my motor had an auxiliary charging circuit so I now charge my batteries independently which is great, no need for vsr etc. When ordering your new motor enquire about the aux charging circuit cable. Yammy wanted $150 but as the blanking plug on the circuit had a blanking grommet on the end I just replaced the grommet with a sealing O ring, inserted a cable and crimped the required lug on, all for about $12. I did run it through a circuit breaker and still have 2 way switching available if ever the crank fails.

[Smakka2301]

In my humble opinion as an Electronic Engineer ... you should solder the crimped connections for electrical conductivity. The solder will stiffen the end of the wire which may then cause issues in a situation where there is high vibration. Supporting the wiring mechanically should stop this. Look for very solid crimps also. The Narva brand is not what I'd call adequate for this situation. Look to use heatshrink. Always plan to run sufficient wire to allow re-termination. Look for a wire that has more smaller strands than a few larger strands - it will be more flexible. In some applications, running a couple of smaller cables in parallel is better from a cost and maintenance perspective. Smaller and flexible cables could be a lot easier to pull through conduit also. You can vary the sizing of cabling. The cables for the motor starting will obviously be very substantial. Cables for other equipment wont need to be near this size. If you are running more energy efficient items like LED lights the current requirements are very much less than the 'old days'.

There is a tape used in marine and extreme environmental (it might have been Denso tape). It was used by myself to protect external antennae connections in the NW of WA in the mines. It has a petroleum jelly type of substance impregnated onto a cloth tape. It was horrific to work with in that it really took a lot to get it off your hands but it was cyclone proof to a great extent. That stuff protects electrical joints for sure.

Telstra used a silicon muck inside their heatshrink which would ooze out during the shrinking but would cover the wire from water ingress. Something like that would probably work. Perhaps you could use a bit from a caulking gun ...

2 cents ...

[myusernam]

Self amalgamating tape. Can get it lots of places

[Dignity]

Self amalgamating tape. Can get it lots of places

Agree, much easier than Denso tape to use. Denso is good to wrap around your axles to stop them rusting.

[blacklab]

Great Info Guys. Am taking notes, In the process of drawing up my wiring plan now......... Thanks


Col

[scottar]

Thanks for the detailed reply Scott...much appreciated...

I ordered a blue sea fuse block with negative bus but i also have a fused rocker panel switchboard so was thinking of a seperate negative bus for that...

yep I will have a house battery …..so should I also install a VSR...?

I have never had a 2nd battery before so I'm undecided on what to look for should I be looking at deep cycle , crank battery or a combination of both..?

No issue with the second negative busbar. I normally use switch panels without the fuses and keep all the fuses in the one location as a preferred method but there are no hard and fast rules apart from making sure everything is protected by a fuse or breaker.

As Dignity has posted, there are a few ways to charge house banks these days. Like Dignity, my rig has a second charge output that is connected to the house battery thus negating the need for a VSR. Going with one method or the other is IMO the best option. I use a Blue Seas dual circuit battery master switch with paralleling feature https://www.bluesea.com/products/pro...witch/featured to isolate both batteries from the engine at once at the end of the day and a separate switch to connect the house battery to the gear in the boat. If your engine doesn't have this facility or it is cost prohibitive to fit, A VSR is the next best. Just make sure there is also a manual override built in or in parallel via a switch.


Given you are running a fridge, I would be looking at a deep cycle - possibly AGM, that can function as an emergency crank battery if required. You certainly will not want a battery that is predominantly a starting battery as your house.

[Dignity]

No issue with the second negative busbar. I normally use switch panels without the fuses and keep all the fuses in the one location as a preferred method but there are no hard and fast rules apart from making sure everything is protected by a fuse or breaker.

As Dignity has posted, there are a few ways to charge house banks these days. Like Dignity, my rig has a second charge output that is connected to the house battery thus negating the need for a VSR. Going with one method or the other is IMO the best option. I use a Blue Seas dual circuit battery master switch with paralleling feature https://www.bluesea.com/products/pro...witch/featured to isolate both batteries from the engine at once at the end of the day and a separate switch to connect the house battery to the gear in the boat. If your engine doesn't have this facility or it is cost prohibitive to fit, A VSR is the next best. Just make sure there is also a manual override built in or in parallel via a switch.


Given you are running a fridge, I would be looking at a deep cycle - possibly AGM, that can function as an emergency crank battery if required. You certainly will not want a battery that is predominantly a starting battery as your house.

I neglected to mention that I also run separate switches, once again I followed Scottars advice so my setup is pretty well much the same although I included a circuit breaker from the aux charging circuit then a isolation switch. I might have to have a look at the parallel setup. If you want an emergency crank battery then the LiFeo4 will NOT be an option so you can save some moneys there.

Sam

[scottar]

I neglected to mention that I also run separate switches, once again I followed Scottars advice so my setup is pretty well much the same although I included a circuit breaker from the aux charging circuit then a isolation switch. I might have to have a look at the parallel setup. If you want an emergency crank battery then the LiFeo4 will NOT be an option so you can save some moneys there.

Sam

Mine does have an in line fuse Sam. Basically every wire apart from starting cables definitely should have either a breaker or fuse for protection. If you want to go real nuts there are fuses that are big enough to protect starting cables as well but I've never bothered - just make sure that there is absolutely zero chance of any unfused cables chafing through to the hull - something should have probably touched on - one of the most important things in a tin rig is cable chafe protection. Make sure any holes or corners for cable access are at a bare minimum de-burred or preferably protected with some sort of cable protection. Fuses will protect the boat from fires but not from electrolysis caused by contact between a negative hull (caused by bolting on the outboard) and a chafed through wire if it doesn't create a short circuit - usually as a result of corrosion. Also make sure your battery switches are either a closed back variety or are mounted to a non conductive backing plate or similar can happen. It's a good idea up under the dash as well to install a piece of Starboard or Seaboard to mount all your busbars and fuse blocks to. A piece of resin sealed ply is the next best option.