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looks pretty good
worth always having a little bit of circuit protection where possible
also worth having a main supply lead coming out of the "common" post of that 4 position switch and connect to a bus bar. so the engine/house suppply (maybe a winch) etc can be on their own posts. instead of 2 3 or 4 terminals all jammed on the one post
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Generally you don't. Inrush current can be huge and popping fuses on your starter circuit is arguably a more critical safety issue for a boat than unprotected starter wiring. You rely on having an accessible isolator to cut the current if there's an issue like a shorted starter.Originally Posted by blacklab
I'm using Narva mini battery switches (100A continuous; 1000A 5 secs) located right next to each battery for isolation for that reason. Every positive feed that doesn't end up at the starter will also be fused or have a circuit breaker.
That said, if your outboard manual includes a fuse rating for the starter wiring, go ahead and fit one to each main feed.
if you havnt already gone too far into things i would highly recomend using a dual battery DVSR cluster rather than a 4 position switch personaly
You can run your winch to your start battery direct should you want to. obviously the engine needs to be running when winching at any time. but this will help prevent your eletronics suffereing voltage drops when winching "if they are on the house battery"
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The Blue Sea Systems 'Add-A-Battery' kits are super simple and better (IMO) than a straight 1/2/both switch. There are both 65A and 120A versions depending on your alternator output; chances are the 65A will be fine. The cheapest 65A kit is on eBay; the cheapest 120A is on Amazon AU.
The benefit of the Add-A-Battery kits is that they include an automatic charge relay (ACR). When there's no charge coming into the system from an alternator or other source, the ACR connects house wiring to house battery and start wiring to start battery. When voltage exceeds 13.6V on either battery (indicating charge voltage) then it automatically combines the two to allow both banks to charge. No need to remember to switch it manually.
In case of the start battery being flat then you move the switch to 'Combined' and it links the house battery into the start circuit.
Pretty simple to wire up - the below should be close to what you need.
gHTs2EQ.jpg
“In case of the start battery being flat then you move the switch to 'Combined' and it links the house battery into the start circuit.”
Although unlikely would the above mean that in the instance of your starter battery completely collapsing you would be in trouble? Linking both batteries would see the buggered battery drain it really quick for no benefit, whereas being able to switch to battery 2 to use as the starter in the ‘off/1/2/both’ switch setup avoids this risk
The ACR automatically isolates the two batteries + throws an LED error message if either battery is dead (<9.5V), so no risk of one battery draining the other while you're underway and they're charging. If you're stopped and the Start battery is dead, you'd just switch off the Start battery isolator before moving the switch to 'COMBINE BATTERIES' and start off the House bank. No risk of draining the House battery.
IMO manual switches are a higher risk because they rely on you to remember to switch them - particularly an issue if you switch to Both while running to charge both banks and forget to switch back when anchoring up.
As mentioned by Mopheus the bluesea system add a battery kit is very good.
In addition a 4 pole isolator is often over looked. The traditional 3 pole isolator is such a bad design. you can generally only charge 1 battery at a time and everything runs off battery 1 or 2.
4 pole isolator is fantastic as its keeps start and house battery seperate aswell as charging them at the same time with a VSR.
also stops voltage drop on startup from turning your sounder off.
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