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Date: 18 July 2018. Storing the Power (battery charts) (#3 in reefer series)



This is the final installment in the three-part series about off-the-grid decadence. It covers what you need to know to have it all, including refrigeration, while anchored in remote coves. Today's article is Part Three in the series. It focuses on batteries and is entitled Storing the Power (battery charts)


Clicking through is not a favorite of mine. I want all the information on one page. Thus I put the three decadence afloat articles together. They detail how to have refrigeration off-the-grid. The complete series with all the information contained in the three articles is here:

Powering the Refrigerator (complete series)


#3) The power provided by wind, solar
and your alternator is stored in batteries.


First, please note that I am specifically speaking about the lower cost lead acid batteries sold at places such as Walmart. That is what I have aboard Seaweed. Decades ago we had Lead Acid on our 40'er too. Details on her can be found in The Fishing Boat article.

Though in my dreams I have those spiffy new Lithium batteries, that will not happen for many years. For those with the funds and knowledge to install lithium batts, gosh, you are fortunate. I will be following in your wake eventually. My research (see Calder's Boatowners Mechanical and Electrical Manual 4the Edition) says the charging system is quite finicky. You have got to get it correct!

Life is wonderful just as as it is though...

Photo of a rainbow off Manjack Cay in the Bahamas taken by my friend Irene.

Old-timers would say you need four times the charging capacity as a minimum for batteries. Because I have 445 watts of solar, the panels generate approximately 150 Amp hours per day. Therefore, at a bare minimum, I should have 600 Amps of battery storage available.


At the top of the picture and bottom, you can see batteries tucked outbound of the engine along the stringers.

The more power I have stored in batteries, the better. The goal is to have power to spare in case of overcast skies. Having lots of batteries gives me wiggle room (aka time). That means I can wait a few days for the sun to reappear and recharge my batts.

There is a level of confidence in knowing that even if I the batteries do get low, eventually they will recharge without any intervention from me. The wind will blow. The sun will shine. With either or both of those things I will soon enough have plenty of power.

My batteries are fully charged in absorption mode at 14.2 volts.



12-volt Battery Chart

Size Dimensions
Length x Width x Height
Weight Amp Hours
Group 24 10.25" x 6.75" x 9" 38 lbs. 70-85 Ah
Group 27 12" x 7" x 8.75" 65 lbs. 109 Ah
Group 29 13" x 6.75" x 9.5" 62 lbs. 115 Ah
Group 31 13" x 6.75" x 9.5" 69 lbs. 95-125 Ah
4D 20.75" x 8.75" x 10" 135 lbs. 180-215 Ah
8D 20.75" x 11" x 10.25" 162 lbs.  225-255 Ah

In the United States most boats have 12-volt systems. European boats often use 24-volts as their standard. Some boats have a mixture. It gets real "interesting" when it is that complicated. I am grateful my Seaweed runs on 12-volts at present.

Many chose golf cart aka 6-volt batts. With 6-volt batteries you must wire them in series. When batteries are wired in series the amperage stays the same and the voltage increases. (connect + to -) Details can be found in the Diagnosing a Bad Battery article.

6-volt Battery Chart
Trojan T-105's 10.5" x 7" x 11" 62 lbs. 225 Ah
Trojan L-16 11.75" x 7" x 16.75" 123 lbs. 390 Ah


I have Group 27 batteries aboard Seaweed. Each weighs 65 pounds.  Although I have ten, only nine are in my House Banks. The Start Battery is sitting under the step in my pilothouse, starboard side. Having such a sizable house bank allows me the freedom others might not have.

Aboard Seaweed I don't much worry about having sufficient power. That's because I have a lot of batteries.

Living on my Seaweed is wonderful. I am truly fortunate.

The views change however the sunsets remain wondrous.

Because Seaweed is relatively light weight, the 650 pounds of batteries in bottom center of my boat have helped with her *pitching. She rides better now with the additional weight. The downside is I've lost about 1 mph of speed. That's a lot to lose in a small boat.

*Pitching is when your boat rocks fore and aft. Imagine a porpoise leaping through the waves. Another way to think about pitching is to picture yourself on a teeter-totter. That is pitching. Rolling is when  you rock side to side. The side to side motion is likely to cause seasickness.

There is a porpoise just forward of the out-rigger pole. Photo taken when I was on DoodleBug, a 40' Viking.

Life aboard Seaweed is lots more relaxed now than it was in the past. Years ago I could only dream about having the setup I now have. The 445 watts of solar translates to 150 Amps of power on a sunny day. By noontime my batts are full.

Afternoons I watch a DVD movie and have a bowl of popcorn. Details about nuking popcorn can be found in the Popcorn for One (and Stone-wave Update) article. 

Life off the grid is so tough. Somehow I manage... (wink) (wink) Popcorn anyone?

Side Note: Though I have a lot of batteries I did not buy them all at one time. They were accumulated over time. The Experts will say buy all at the same time, with identical dates on the batteries. That is the Ideal. I do not live in an ideal world.

Because my batteries were purchased over time, I split them into two banks. Bank One has the batteries that are between 5-8 years old. The second bank has batteries that are all two or three years old. This is not perfect. It is Good Enough.

One thing I am meticulous about is checking my batteries on the first of each month. Because my batts are easy to get to, this is not a problem. When you shop for your Last Boat, having easy access to the mechanical bits will make a world of difference.

This is Paul from Sunrize Marine. He finished the work of getting the Kubota up and running. Thank you Paul!
You met Paul in the
Getting Betsy Ready-to-Go article. Every time I start the engine I'm grateful.

But I digress... Seaweed runs and that's because of friends met out here.

As for this life of decadence, it is because of three things.

  1. Patience: No boat has it all right from the get-go. Every vessel requires additional tweaks, improvements and upgrades. The home I have now is far superior to the one I bought over ten years ago. She is my comfortable oasis. Each year I save for another improvement.

  2. Ability to make power without fuel: The wind generator provides some power, especially at night. Primarily however it is the solar panels that keep Seaweed in juice aka power. When I had 275 watts, that was not enough. At 445 watts, I never run out of power.

  3. Storage is Critical: Having plenty of batteries means that when the sun does not shine for a few days it is okay. I can still keep my life running smoothly. After I install that last battery I will have over 1kw of battery power. How cool is that?!?

Having "regular" storage for life's fun things is important too. It's not just mechanics that makes a boat a great choice. Contentment includes having the things that please you aboard too. I have both and know I am very VERY fortunate.

Decadence works for me. I enjoy a
 comfortable life aboard Seaweed.

For more information on power, please also read the Solar, Batteries and an Inverter series.

Thanks for reading.

How many batteries do you have in the bilges?
And, what type of batteries do you have? (lead acid, AGM, golf cart, lithium)


2018, 2023

Categories: Boat Talk, Boats, Books, Characters, Gear, Recommendations, Wild Things,

Generating Power (#2 in the reefer series) ~ Previous Post ...    ... Next Post ~ Scallions - Second Life


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