What size battery cable?

woodster · Jan 22, 2015

for no/minimal difference in cost i would go 4 ga and fuse it to 150% of your expected load..or fuse it the rating for 4 ga are you going to controll all those things with breaker or switches

woodster · Jan 22, 2015

i just checked prices and i see what you mean looks like for an 8 position panel with breakers it would run about 225.00 with led indicators

Crazy Dave Condon · Jan 22, 2015

generally #6 cables were standard by most and will do just nice for what you are doing.

woodster · Jan 22, 2015

#6 will give you a 50 amp supply #4 will give you 80 amp supply so if you have no plans to grow later..... as Dave says #6 will be fine i would think

kito · Jan 22, 2015

I am rewiring my ac and dc. I may have to rethink this. I have 4 ga from bat to bat switch and was going to run 2 10ga wires off the switch, one to each panel. One panel is only 2 foot away and the other is about 6 foot. I reck'n I thought I would never have all my dc on at the same time but you never know. I better go with 2 8 ga wires to be safe.

Deadhead · Jan 22, 2015

Take the guess work out of it. Calculate the size cable you need using this:

http://www.genuinedealz.com/voltage-drop-calculator

twalker H260 · Jan 22, 2015

Bad obsession - if you have a fuse panel with the round holders such as this panel:

http://shop.hunterowners.com/prod.php?6532/

You can replace the fuse holders with resettable breakers such as these

http://shop.hunterowners.com/prod.php?4881/

A lot cheaper than the toggle style breaker panels!

Crazy Dave Condon · Jan 23, 2015

battery cable concerns for DC is different for the wire used in AC as you would want to use a marine grade 12-3. Do not use the cable purchased from Lowes or Home depot as you are around water. The marine grade for AC 12-3 is more flexible and double sheathed. As for the DC or 12 volt, the use of yellow coated wire for negative ground is recommended to avoid confusion of the hot side of AC 12-3 which is black. Knew too many batteries blown up with black hot side of AC 12-3 attached to negative battery terminals.

kito · Jan 23, 2015

Thanks for the tip Dave. I was going to place an order for 100 feet of black tinned copper wire tomorrow but will change to yellow instead.

Stu Jackson · Jan 23, 2015

Bad Obsession said:
What size should I use? I am not sure right now, and not at the boat, of the size of the fuse that I have in these. I am thinking 15amp breaker?

BO, not sure with all this input why you are still asking. The "size of the fuse" where? On the batteries? Maine Sail has discussed this many times. It depends on the size of the wire you choose.

I am sure you've developed a wiring diagram before you start the wiring, right?

Charlie Wing's books is very good on this stuff. It used to be available on scribd, but they took it down. PM me and I'll send it to you in a PDF.

twalker H260 · Jan 23, 2015

Fuse size is usually determined by the size of wire that it is protecting - unless it is protecting a specific piece of equipment (which is of lower amperage than the wire size would need to protect it)

You should be fairly safe to simply determine the rating of the current fuse and replace with a comparably rated resettable breaker.

Here is a link to an very good chart to determine the required fuse ratings on different wires in different situations.

http://assets.bluesea.com/files/resources/reference/20010.pdf

You could also have a look at wiring diagrams in current vessels to get a rough feel of what is used in different applications.

Should mention that these breakers are what was used on our 2004 oem panel.
No real downsides that I'm aware of - and you don't have to have a handful of spare fuses rolling around somewhere that you can't find or you have the wrong size!