Battery placement on small boats.

[Ed Schenck]

In 1979 my H37-cutter was queen of the Hunter fleet. Still I consider it a small boat when looking for interior or storage space. A new H38 has twice the space. MaineSail's latest post about batteries got me thinking more about mine. A lot of you Cherubini owners have moved yours. I have not.

I have my start battery and one house battery in the original location, on the hull under the icebox. I have two more on the ledge behind the icebox and a fourth house AGM in the bilge. They are all secured with web straps but are not in boxes. They do have the heavy rubber insulators over the posts but those don't fit very well. Because of the inverter/charger, a combiner, and the shunt for the Link 2000, some of the posts are overloaded. Hard to keep all of that insulated.

Now I am considering Maine's recommendation to fuse the two battery banks. And wondering how I am going to get down in there to install and protect them. To work on the start battery I have to remove the other three and get into the locker with my legs over the engine. There is nothing else up under there so that fuse would be easily insulated. But the other batteries are all exposed to all the crap in that locker.

Just thinking out loud and wondering if any of you have tackled this. And my boat is a shoal draft. The bilge space is all used up. Picture is of the starboard locker with the Freedom 20 on the back of the icebox. And before I added a second battery on that shelf.

 

[Mathurin]

I solved the problem by building a new compartement in which I can easily access all batteries, and where there is enough space to put the fuses. Otherwise, you could always put the fuse behind your electrical panel, not the best as they are not as close to the batteries, but it's better than nothing.

http://forums.hunter.sailboatowners.com/attachment.php?attachmentid=32370&d=1279634871

http://forums.hunter.sailboatowners.com/attachment.php?attachmentid=32369&d=1279634871

 

[Johnb]

I have been thinking about how necessary it really is to have fuses right at the batteries. What is the likliehood in a plastic boat that a short is going to occur in the 24 or 30 inches of heavy duty cable that would run from the battery to a more accessable location? I guess a tiny fraction of the likliehood of the positive wire to the starter solenoid for example fracturing or wearing though and touching on the engine. This could be lessened by routing, supporting and protecting the wires. Therefore I would consider placing the fuses in a more accessable location.

It is way more important (IMHO) to protect the terminals from inadvertant contact, and also contain potential spillage from damaged batteries, and protect anything stored near them by putting the batteries in boxes.

Given that your new engine is much smaller than your previous one could you move the starting battery into the engine compartment. It could sit there for years not getting any attention, just like the ones in vehicles. A sealed no maintenance battery is ideal for that purpose.

My understanding is European standards require separate batteries for house and critical loads (navigation lights, VHF etc) and starting batteries. This sounds like a good idea and can be achieved with just 3 batteries - maybe the way to go.

I would also provide for starting the engine from one of the other batteries in an emergency. Last summer in England we used one half of a set of jumper cables to jump from the house bank to the starting battery to get the diesel on a canal boat started up.

 

[Ed Schenck]

MaineSail says the battery fuse must be within seven inches. His pictures show them mounted right on the battery. That's easy enough if you have a nice battery room.

My starter battery is an untouched(and unseen) 900CCA AGM, strictly starter(yellow top). My other four are also AGMs. So everything is sealed, no boxes are required. Shorting across the posts is the only worry. The engine will start immediately on either bank. In fact I almost never use position#1, the starter battery.

I cannot use the space the Mathurins used. My A/C is in that cabinet at floor level.

 

[Seattle Scott]

Ed at a minimum

I would secure some rubber matting over the tops of the battaries to further protect the terminals. I have one start batt in the bottom of that locker, but its in a box so I can dump stuff on/around it.

 

[sandpiper10471]

Ed S.: you say you have a battery "under" the icebox/reefer? My 81 has absolutely no room there. The icebox goes right down to the boat bottom. Is this perhaps another modification of Hunter that should be included in the evolution thread?

 

[Jim Legere]

Battery location & fuses

Sandpiper:

I think Ed S. means inboard and beside the icebox, in the stbd. cockpit locker. It is sort of "under" the top part of the icebox that protrudes into the cockpit locker and was meant to be where you loaded the blocks of ice in...

My boat (1983) also had two batteries in this location. I left a GP 27 "starter" battery in this location and, as Ed says, it doesn't get checked very often since I have to fold myself into the cockpit locker to get at it. I located 3 GP 24 batteries under the cabin sole on a removable shelf I built for that purpose. There is still more than a foot of space in the bilge below the shelf (that old worry about batteries and salt water).

As to fuses for batteries, ABYC Recommended Practices states:
"E-9.11.1 Overcurrent Protection Device Location - Ungrounded

conductors shall be provided with overcurrent protection within a
distance of 7 inches (175mm) of the point at which the conductor
is connected to the source of power measured along the conductor.
See Figure 11.
EXCEPTIONS: 1. Cranking motor conductors.
2. If the conductor is connected directly to the battery terminal
and is contained throughout its entire distance in a sheath or
enclosure such as a conduit, junction box, control box or enclosed
panel, the overcurrent protection shall be placed as close as
practicable to the battery, but not to exceed 72 inches (1.83m).
3. If the conductor is connected to a source of power other than a
battery terminal and is contained throughout its entire distance
in a sheath or enclosure such as a conduit, junction box, control
box or enclosed panel, the overcurrent protection shall be placed
as close as practicable to the point of connection to the source​

of power, but not to exceed 40 inches (1.02m)."

So, on our "stock" H37Cs, the wires go straight to the battery switch and on to the engine starter and then from there a smaller wire goes onto to the DC panel. Technically the wire from the starter to the DC panel should be fused, but I doubt that it was required back when our boats were built. When I redid my wiring, I ran a heavier wire from the DC Panel to the battery switch and installed a fuse next to the battery switch to satisfy the 7" requirement.

Here is a picture of the 80 amp fuse for the DC panel installed in the starboard cockpit locker, next to the back of the battery switch (which is on the other side of the hole). The thick white wire coming out of the hole is 7" long and connects the fuse block to the battery switch. The other side of the fuse goes to the DC panel. I think I used #8 AWG wire. BTW, the black wire with the yellow crimp connector is the infamous 3rd wire to the bilge pump. It has an inline fuse, which is sort of shown end-on in the photo.

 

[Ed Schenck]

Scott, I will add that rubber mat at the very least.

Bill, it has been awhile since I have been "under" there. But I don't think the icebox goes down to the hull. I really believe the battery is partially under the box. The battery is down there athwartships. If you measure the distance between the box and the engine bulkhead a battery will not fit "lengthwise". It goes down "widthwise" and then is turned. . . .I think.

Really like your fuse setup Jim. I still have my panel wired from the starter. Early on I changed to #10 wire. When I added the HAM radio I ran a second #10. Neither are fused. I do have an inline fuse to the bilge pump. But your setup does not satisfy the ABYC requirement does it? Are your battery cables in conduits? Oh, and you obviously have the fin keel with the deep bilge.

 

[Jim Legere]

Only a son-of-a-sealawyer knows for sure...

Ed,

I beleive that the wiring to the starter, i.e. the heavy #2AWG wires from the batteries to the battery selector switch and from the switch to the starter, is OK without a fuse under "Exception 1 - Cranking motor conductors". That said, protecting the wires, the battery posts, using rubber mats, etc. is all good! My wires are well secured, run inside corregated plastic wire covers, and my batteries are all in USCG-approved plastic boxes with covers. I had a small electrical fire once on my previous boat (Abin Vega) so I am a bit over the top now when I re-wire things.

Yes, I have the 5' 1" draft keel (I don't consider it much of a "fin" compared to most boats these days). Funny, I had alway thought the shallow draft version had the same keel sump as the deep draft version - maybe not? My bilge is probably +3' deep at the aft end...

 

[Ed Schenck]

Not me Jim. My #2's are just hanging out there. I do have the posts fairly well insulated but will add the rubber mat covering. And I will add conduits for sure. I could do fuses as Maine illustrates, right at the battery. But it would be a major undertaking and hard to insulate.

Jim I have been on a deep bilge H37C, Ed Allen's. The difference is amazing. I don't have a twelve inch depth anyplace. It does make it easy to sponge out though.

 

[sandpiper10471]

Ed S: I love how you always find positives in things. Sponging out the bilge is beyond me with the deep sump. (Not that I would ever get around to it with the shallow sump!) I think I understand where your starter battery sits. There is not much space between the reefer and the engine bulkhead. All I can get in there are a few gallon size jugs of engine oil. At least they don't tip over. And I am sure if my starter battery were there it would NEVER get inspected.
I now have 4 trojan 105's making 2 twelve volts batteries wired in parallel for house sitting in the bilge and a group 27 for the starter at the aft end of the bilge (almost under the sole grate). The battery switch is a simple ON-OFF type and combiners keep me from discharging due to forgetfulness.
When I purchased my 37C, there were two group 27 batteries under the helm seat (Lazarette). I have found no evidence of them ever being in the starboard cockpit locker as per the Hunter wiring diagram. There was a 4 guage wire to the starter. Amazing how much easier the engine starts with a 4-0.

 

[sandpiper10471]

Sorry, that was a 2-0 to the starter.

 

[Johnb]

What Jim Legere did makes perfect sense to me. I would also submit that you could use exception 2 and run each positive wire in a flexible conduit and locate the fuses just ahead of the selector switch.

To my mind that also passes the common sense test. How likely is it that those wires, well protected and in a plastic boat are going to find a way to short to ground?

One thing to remember is that fuses and breakers protect the wire, not the load. As such there should be protection at any point where the wire size decreases and it should be based on the wire immediatley downstream of the protection.

I would like to make one final plug for battery boxes as an additional barrier between the 30% sulfuric acid in the battery and the interior of the boat. I also submit that the thin plastic straps and weeny hold downs that are supplied with battery boxes are inadequate.

When I rebuilt the battery shelf in my boat I used 3/8" ready rod to hold the batteries in place.