Battery Location for CD36

Discussions about Cape Dory, Intrepid and Robinhood sailboats and how we use them. Got questions? Have answers? Provide them here.

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Bob Brown
Posts: 60
Joined: Jun 3rd, '09, 19:22
Location: CD36 Barbara Lee 1981 Hull 41 Haverstraw, NY

Post by Bob Brown »

Russell,

The steering stuffing box was repacked a few years ago by a previous owner. I just replaced the auto hose clamps on her with a couple of serious marine bolt type clamps. If I proceed the annual steering inspection would have to be a serious affair. The auto pilot is attached to the wheel. You never hear of a functioning emergency tiller. It seems emergency tillers are there to give you something to do, a feeling that everything is going to be OK, or they give you time to think about how you are going to fix the problem while you fly back and forth like a flag on a stick.

I'm unsettled on the battery heat issues. On one hand the 1st row of three batteries would be about 24" from the engine, on the other hand they would be mostly below the water line. I belive most batteries over heat because of improper charging or discharging which I feel is caused by an improper electrical installation. The battery manufacture's engineering department might be a good source of information on this topic. I'll see if they can shed some light on our topic.



Matt,

The current batteries are in the port cockpit locker. This change would move them forward, add a second house bank, and lower the center of gravity. We inspected both water tanks located under each settee last season and didn't see any lead ballast in the vicinity. She is new to us last July and sits level. She has had a lot of upgrades since 2005 by the last 3 owners. One was a 16500 BTU AC unit that cuts the hanging locker in half. This unit may have solved some of the balance issues.


Jeff,

She has water tanks under each settee. I haven't looked since last fall but I don't remember enough room in there for 5 batteries. The wire size to handle your voltage drop must be large.
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Matt Cawthorne
Posts: 355
Joined: Mar 2nd, '05, 17:33
Location: CD 36, 1982
Hull # 79

lateral balance

Post by Matt Cawthorne »

John,
my boat has 4 water tanks. the port and starboard water tanks amidships are the same size. The v-berth water tank is centered. The only one not balanced or centered is the quarterberth tank. All in all, the boat, even with the lead listed slightly to port with all tanks empty. Perhaps 1 degree. When I took the lead out the boat listed to port by a scary amount. When the batteries went from the port cockpit locker to the starboard setee the balance returned to being level.

I think that the cables are 2/0. Very expensive, but needed for the longer runs. The cable that was originally in the boat was #4 i believe. it was entirely too small. Some years ago I changed it to #2. With the 2/0 the starting is more crisp, even with the longer runs. Speaking of which, the two red cables run from the battery selector down through the engine compartment and through the side of the engine compartment under the quarterberth. They proceed under the foot support for the nav station through the locker in front of the nav station and finally under the starboard setee. One of the batteries is under the setee and the other is behind it. I use two group 31 batteries.

The black wires go to the shunt for the battery monitor. The ground from there goes to the starter motor, the alternator case and the common bus for the electrical pannel. The alternator (through a circuit breaker) goes to the common terminal of the battery switch. The switch has a field coil break in the event that the batteries are turned off.

Matt
John Stone
Posts: 3621
Joined: Oct 6th, '08, 07:30
Location: S/V Far Reach: CD 36 #61 www.farreachvoayges.net www.farreachvoyages.com

Post by John Stone »

This is an interesting discussion.

Does AGM, gelcell, and lead acid all react the same way to external heat? Perhaps there is an option there.

My boat had the same water tank set up as Matt's. Now they are in the bilge (3 tanks) and the one Q-berth tanks. My boat did not have a list though I don't recall ever running the QB tank dry. It also did not have any extra weight under the settee. If I were to add another tank, which I would like to do, it would bring my water capacity up to 140 gallons. perhaps I would locate it on the port side to counter balance the QB tank and pull from them together.
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Russell
Posts: 2473
Joined: Feb 5th, '05, 11:14
Location: s/v Lady PaulineCape Dory 36 #117

Post by Russell »

John Stone wrote:Does AGM, gelcell, and lead acid all react the same way to external heat? Perhaps there is an option there.
Gels and AGMs are more sensitive to heat, as overheating them will cause them to force vent, which will cause permanent loss of electrolyte. If installed in the engine room you absolutely need a temp sensor on them (and an external 3 stage alternator regulator that supports a temp sensor). What will happen is as the heat rises the regulator will reduce the charging voltage to prevent boiling and venting. This will reduce charging efficiency, but it should still work. Perhaps installing a bilge blower attached to one of the engine room cowls, thats wired to start running when the engine is circut is on, is a good idea, to improve ventilation and lower temps in the area (not sure how much it would help though?).
Russell
s/v (yet to be named) Tayana 42CC
s/v Lady Pauline Cape Dory 36 #117 (for sale)
Bob Brown
Posts: 60
Joined: Jun 3rd, '09, 19:22
Location: CD36 Barbara Lee 1981 Hull 41 Haverstraw, NY

Post by Bob Brown »

This is an interesting article on battery comparisons written by a non biased party.

http://www.vonwentzel.net/Battery/01.Type/index.html

The magic high temperature for any battery seems to be 77F. Every 15 degrees above 77F will reduce battery life by 1/2.

After reading from the above web site this seems to boils down to engine compartment temperature. Has anyone placed a thermometer in their engine compartment and how hot does it get? I can get my head around all the other issues about access to the steering cables and not being able to see the rudder post coming through the hull and feel these issues can be managed with a good maintainance program. The electrical issues with AGM batteries can be solved with a properly engineered electrical system. As discussed earlier it's all about the heat.
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