Batteries under your Bed!?

[Mark in NJ]

Hello All

I have a small 18' sailboat that I am planning to run an electric motor on for auxilary power when I have to navigate tight spaces, dock it, and use when the wind dies.

I Went to SAM's club last night and looked at the $46 golf cart batteries , $99 8D battery, and $100+ spiral AGMs.  The golf car battery cases looked flimsy.  The 8D was impressive looking, and the Spiral AGMs were pricy for their small 100 min reserve capacity.

The battery(s) would be in the cabin, under the v-berth "bed"  I can vent this space to the outside.  I would charge at home before going on a trip (up to 7 days)  and charge every other day or so at marinas with the Vector 20/10/? charger I just ordered.  I am also considering a 15watt solar cell as well, or other solar options.  I even considered running the trolling motor as a generator when there is good wind, but doubt it will reach a high enough voltage or be steady at all.

What do you all think of my situation and potential choices?

Mark

[wdyasq]

I would be concerned with the balance of the boat, putting too much weight in the bow. I would also think how I was going to place the battery(s), run of cable and everything else.  I don't think gassing will be a problem and you could power-vent when the charger was on.  

As far as placement goes - I would tend to use golf cart batteries about center of displacement, usually just aft of center - it can be located by having someone watch the boat while someone else walks on center-line and tells you where the boat 'floats right.'  8D's are far more battery than I would like to handle going into a V-berth of a small boat.

Remember whatever you do a 50 or 100 pound lead weight filled with acid will not be fun

if it comes loose in a storm and could sink a boat of almost any size.  Build good battery box(es) and avoid learning first-hand how the term of 'Loose Cannon' came about.

Ron

[ghurd]

I personally would not use the AGM.

The solar panel will need to be at least 32 or 50W to do much good.

A 15W panel will do little more than keep up with self discharge.

I am curious what other people think about the 8D battery.

Just 2 cents.

G-

[Mark in NJ]

Thanks for the advice, and comments.  I tend to agree that the golf batteries would be a-lot easier to handle, and would have the possability of being removed in the off-season.  The problem with the ones I saw was the flimsy cases and tall "tippy" size. The whole battery box thing sounds like a decent ammount of work.  Under the Vee birth is a compartment accessable by hatches beneath the cushions.  Do you think there would be serious heat issues if I install a plywood base, and then fill the rest of the compartment with construction foam, the kind that comes in a can "great stuff"? I could wrap the batteries in something so the foam wound not stick directly to them, and even leave a small space around them, like a 1/2 inch or so.  Or perhaps, plywood "boxes" around the batteries, supported laterally by the rest of the compartment being filled with foam. I like this idea!

I am not too concerned about the sailing characteristics with 100-150 lbs under the vee birth, because it seems to sail better with weight forward anyway, kind of a design flaw, docummented by others as well.

It is a "sovereign 18"

Mark

[veewee77]

The 'flimsy" cases on the golf gar batteries shouldn't be a problem.  Have you seen how some people drive their golf cars?  My geuss is that the boat will never do a hard 'ramp' off of something, or be subjected to a gravel road full of potholes at 30 miles an hour.  I know boats will take somewhat of a beating in a storm, but not a vibrating hammer-blow type of beating.

Secure them good and they should survive it.  And put acid-absorbing mat under every one of them, and even up the sides if they are in a box.

P.S. Secure them good with good materials over the top since you don't want them to come up and or out in the event of a steep sway.

Doug

[electrondady1]

if possible you should put your battery box on gimbals like a stove, that way, if your on a tac and really healed over you won't have to worry about acid splashing around.what about those dry cell type rigs they use for starting cars and as a powersource for camping?  

[Ungrounded Lightning Rod]

No I would not do that.

I'd use deep cycle batteries in standard case sizes, as are used on mobile homes and boats.  These are quite capable of handling significant tilt without spilling.  (It corresponds to the side-forces they receive in a turn.  Tangent of coefficient of friction.)

Then I'd put them in the sturdy, flexible, plastic cases used to protect them from weather (and their surroundings from them) while mounted in places like out on the hitch assembly at the front of a travel trailer.  (This will also help keep salt spray out of the vents and off the terminals - a good idea if you don't like corrosion and chlorine gas.)

Then I'd find a place, or a pair of places, low in the boat and positioned to not affect (or to improve) the trim - up against a bulkhead (like the side of the V-berth).  And I'd provide a very sturdy mount for the strap kit that came with the box, and use that to fasten them securely in position - so they won't slide around as the boat heels.  And I'd use heavy cables fastened solidly as well, as a backup system to limit the battery's travel (and keep it upright) if the strap lets go.  (Letting that weight move is like having an equivalent amount of flooding - it kills your static stability by shifting to the low side and encouraging further roll.)

This is EXACTLY what the designers of sailboats do.

Example:  Hake Yachts.  Battery in our Seaward 23 is in such a plastic box fastened under the portside settee, against its inner side, near centerline both fore-aft and port-starboard.  The slight bias toward bow and port is partially compensated for (depending on fill state) by the removable 3-gallon diesel fuel tank (for the inboard auxiliary) at the starboard rear corner of the cockpit.

The Catalina 22 we had previously (with an outboard auxiliary) did the same thing in a different location for the "house battery" powering the lights and radio.

[Dennis the bus dweller]

Hi Mark

I have 24 Interstate workaholic 220 amp hour golf cart batteries under the bunks in my bus/home and these things work great. I keep them charged with 1200 watts of PV panels and an Air-X wind turbine. T I just bought 6/6 volt Rolls 820 amp hour deep cycle batteries for my bus/home and will be putting 12 of the workaholics in my rolling leather shop with 1200 watts of PV's on it as well. The golf cart batteries are a great buy.

Peace along the way

Dennis the bus dweller N.Y.

 

[electrondady1]

hey mark, whats your boats name?

[Wolvenar]

One added comment:

I am sure there is a lot of debate about high strand count wire, but such flexable stuff may be a requirement in boats for insurance and other purposes.

I believe that solid wire and/or any type of wire that may be remotely brittle are not allowed in a marine enviroment.

Wolv

[Nando]

I would suggest a solar panel with greater wattage, at least 75 watts.

Charging on the way will need a good propeller for the Trolling motor to generate enough power, it should be around 18 to 24 inches in diameter with a 7 TSR, though I can not guarantee it because I do not know the specifications of it as a generator.

If you are going away for 7 days, or so, think in a small 200 watts gasoline operated generator for emergency.

Also, think in a small 10-25 watts wind mill at low wind velocity.

Regards

Nando

[Mark in NJ]

Dennis, do you have any pictures of your bus on the web?

Mark

mmarussich@yahoo.com

[Ungrounded Lightning Rod]

Also on the insulation.

There are requirements on the connectors you use, too.  Corrosion-resistance in a saltwater environment is the issue.

Don't use automotive crimp-ons.

Get your stuff at a marine supply store, and pay the extra bux.  It'll be a lot more expensive if something fails when you're away from dock.

It's a lot harder to walk back if you have a problem, and if you don't have a towing insurance contract and don't handle it just right the guy who helps you out gets a claim on your boat.  (For starters, don't take HIS line, give him YOURS.)

[JW]

SMILES

JW

[JW]

JW

[ignesandros]

Sounds fine with just a plywood box if you secure it. Make sure the batteries fit snugly and don't have any travel. Check out the "Building a trolling motor generator" topic if you haven't already. It sounds like that would be quite good for your purposes. It might even be possible to use your genny as your motor and vice-versa. Definitely use stranded copper or alluminum (corrosion resistant but more impedance) wiring. If you've ever experienced water in your V-birth, you'll definitely want to seal the plywood with a water sealer and silicone caulking.

-Andrew

[ghurd]

I do not believe the trolling motor will reach 12V.

The speed control could also cuase problems for charging a battery with it.

G-