Housebank fusing

[Uncle Bob]

Hi, a question for the electrical guru's, I have decided that the house bank definately should be fused, what configuration would you guys recommend ?
The battery bank consists of 6 235 ah golf cart batteries wired as three pairs, all to a common point thence to switching which would enable the house bank to be used as a start battery should the need arise.
I was considering a 150 amp fuse to each battery pair mounted within 6 inches of each pair, is this overkill, would 100 amp be sufficient ?
Would it be better (and cheaper ) to just use one fuse at the common point ?
Would value all your opinions, thanks.

[skipmac]

If the three battery pairs are close together, in a box, cables protected (which is exactly my configuration) I feel fine with one fuse (or in my case a double fuse) at the battery terminal where the output cable is connected.

I really love the Blue Sea systems double terminal fuse like this. Blue Sea Systems Dual Terminal Fuse Block p/n 2151

I fuse one for the house loads 60 amps, and the other fuse 250 amp for a backup cable to the starting system.

[skipmac]

Oh, to the question about the size of the fuse, choose the max rating fuse to match the size of the smallest, longest cable from the battery to the DC panel. The fuse it to protect the wire, IE if there's a short in the system the fuse blows before the cable catches fire. I chose the fuse based on the max load plus some that I would ever seen the DC system. The large loads, starter motor and anchor windlass are on a separate cable and fuse.

[Singleprop]

You can get single fuse holders for $7.5 qand fuses for $6 at waytekwire - not sure if they have the double fuse holder.

My understanding of the double fuse holder is that it can use 300A max (not 2 x 300A as the double indicates) might be wrong though...

[rwidman]

Chose the fuse rating to protect the cable as skipmac stated. You can use a smaller value if you want to but not a larger value.

[boatbod]

Follow the ABYC E-11 standard for fusing and you won't go far wrong. As mentioned by others, you are sizing the fuse based on the ampacity of the feeder cable.

For large house banks using 2/0 AWG I am partial to 300A Class T fuses as they tolerate surges and are very robust.

[wrwakefield]

Originally Posted by Uncle Bob

Hi, a question for the electrical guru's, I have decided that the house bank definately should be fused, what configuration would you guys recommend ?
The battery bank consists of 6 235 ah golf cart batteries wired as three pairs, all to a common point thence to switching which would enable the house bank to be used as a start battery should the need arise.
I was considering a 150 amp fuse to each battery pair mounted within 6 inches of each pair, is this overkill, would 100 amp be sufficient ?
Would it be better (and cheaper ) to just use one fuse at the common point ?
Would value all your opinions, thanks.

Hey Rob,

As others advised, a single fuse sized for your smallest cable run length from your battery bank to the distribution panel will add the protection you are after.

That is how our house bank is currently set up as well. [8- 6 volt golf cart batteries in one sealed, vented battery locker...]

However, next time I replace the batteries I intend to fuse each pair of 6 volt batteries [in series] so I can easily isolate a bad battery [and its mate since they are 6 VDC and my boat is 12VDC...] This bank of 4 fuses will be located where I can easily get to it. This means I will have 4 [lower capacity] fuses for each of 4 pair of batteries, and one main fuse [higher capacity] for the primary lead to the distribution system. [I have 3rd party schematics and more info if you are interested...]

This is just another way of looking at it, and a fairly common approach for batteries that are not readily accessible... If your batteries are accessible, then this may be overkill...

Also, it may be worth mentioning that since my battery bank is secured in a less than accessible locker, I installed a centralized watering system to keep them topped-up. Works great. There are more details [and photos and links] on my blog post about replacing the battery bank if you are interested...

It is great you are fusing your house bank. Otherwise we all have a floating 12 volt toaster if something goes wrong...

Cheers! Bill