Second battery in Com Pac 16 ll

[Garyandjoanlee]

 I added a second battery to my CP16  against the forward wooden bulkhead on the otherside of my original battery. I drilled two 3/4"holes in the bulkhead just above the battery boxes for the short cables (Red to red- black to black) to connect the batteries. I drilled two more holes just below the handle height of the battery boxes and threaded a motorcycle strap around both boxes. I used an epoxy to secure blocks to the floor on the 3 sides of the new battery box and used the battery box lid with strap anchors screwed to the floor and bulkhead for vertical security. This is all to increase my electrical storage capacity. Sorry- the photos are obviously sideways! Floot to the right!

[Floridagent]

On my iPhone 7 the pictures right themselves when enlarged.
Nice neat work!

[tmw]

Looks nice. I'm surprised you wired them in parallel. My backup battery is a car jump start battery with maybe 10 ah, and I keep it disconnected until needed so I won't be surprised and completely empty if things rapidly go to to zero.

How much capacity do you have? I hate the weight of my 55 ah lead aid battery, but lithium is crazy pricey.

[Citroen/Dave]

Gary,

Great idea.  But batteries should be identical.  I believe the weaker battery will always pull down the stronger to the same level of weakness if they are not matched.  If one charges to 80% and the other to 100%, the weaker will pull the stronger down to 80%.  I use my two batteries sequentially, the weaker one first so I have a little more backup with the stronger one.  I also have a light weight car jump-start battery for emergency use.   

I was surprised on Tim's boat last year after we pulled out of a race in the dark when his outboard ran out of gas in the tail end of a violent storm on Smith Mountain Lake.  I didn't realize how dependent we could be on having "no" back-up power.   In this case, Tim refilled the outboard in the dark, in the rain. I was concerned he might get rain water in the tank. 

On my boat, I simply move the red cable clamp from one battery to the other; I have a common black ground cables to both batteries. On you set up I would have a simple switch to connect the main red cable from one battery to the other.

Dave

[Garyandjoanlee]

The batteries are the same here-and connected in parallel to stay at 12v and it is all to boost storage. I use an electric motor to go to / from the pier and am about to install a chart plotter so I really wanted more 12v storage. I use a 25 watt solar panel mounted on a post next to where I store the trailer to keep it all charged. The clips in the pic are from the disconnected solar charger- have heavy 12" cables connecting both batteries to each other. Thought about securing the new battery in FRONT of the old one but the hull would not let the battery box rest flat enough. Since there is nothing going on in front of the mast compression post anyhow- it was a more secure location. May build a nice box around it if I can ever find teak that cost less than my boat.

[brackish]

Ah the confusion I had is cleared.  Electric motor.  My thought was why two batteries on a 16?  When I had an electric start motor on my 23, I had a start battery and a house battery.  Since I got rid of that heavy beast and got the sail pro, I only need one despite a ton of connected load.  The only reason I haven't removed the second battery is I have no place to put it and no use for it. So it will remain back up for the rest of its useful life.

[tmw]

So it will remain back up for the rest of its useful life.

This is probably off-topic, but what do you do with an SLA battery that is no longer useful?  I inherited one that won't hold a charge, and curious about the appropriate method of disposal.

[brackish]

This is probably off-topic, but what do you do with an SLA battery that is no longer useful?  I inherited one that won't hold a charge, and curious about the appropriate method of disposal.

Easy around here, there is a metal salvage yard about five miles from my house.  SMS, think it stands for Southern Metal Salvage.  I save all my old scrap metal and every so often go over there and sell it.  18 cents a pound for general scrap steel, much more for aluminum, copper, copper wire including old motors, depending on size an SLA battery can bring up to $7.00.

[Garyandjoanlee]

Dead batteries are not necessarily dead. Get a NOCO Genius battery charger and use the "dead battery" button. Can bring them back to life. Amazon $59

[alsantini]

Great looking install.  Have you given any thought to an A B switch?  My factory installed 2 battery set-up on my Eclipse uses one and I like it.  I follow the basic rule of, is the day even or odd numbered and use the corresponding 1 or 2 position.  When one of the batteries dies I will probably not replace it.  The switch does prevent the discharge into the weaker battery problem unless I use the "both" position.  I like the ability to disconnect the batteries when I leave the boat using the OFF position.
BTW our local O'Reilys auto parts accepts dead batteries.  No cash back unless you are replacing with a new one of theirs but they do accept them.  Sail On

[Garyandjoanlee]

Thank you. Yes, I do like the idea of the "A/B/Off" switch. Will probably add it after I complete the list of tasks in front of me!   As for dead batteries- i'd find a place to stow one or two in the garage. They really nail you for not having a core to turn in when yoiu buy a new battery.