Date: 7 April 2016. Batteries Store
Power (Part I)
Part I, entitled
Batteries Store Power.
A boater wrote asking about
solar power. Like many I have embraced the solar movement. The price
has come down on the panels. Nothing moves so nothing breaks. It is
quiet. What solar panels are not is the complete package. There's
more to it.
with one 75 watt panel mounted over the cockpit in front of the wind
If you have the room for them, solar is definitely the way to
augment your power supply. I love mine. The one complaint I have
heard time and again is "I wish I had more
space for solar. I envy you folks with room for multiple panels."
A few years back I added two more
100 watt panels atop the pilothouse.
Aboard Seaweed I had a total of 275 watts. At that time I had four
100 amp batteries. The combination was not enough to run my
refrigerator 24/7 unless it was windy. Then the wind generator
kicked in enough power to put me over the top on power.
I like to make
more power than I use thus the batteries stay near full at all
Calder's it is best to use the least percentage of battery
Mini-Lesson on Power and Battery Capacity.
I'm going to use round
numbers for this explanation. It's easier for me to understand
Your standard *Group 27
or *Group 29 battery holds a certain number of amp hours aka
power. For math's sake, let's call it 100 amp hours per
battery. With the economical batteries (read: cheap) it is
suggested that we never use more than half of the amperage in
the battery. Thus our 100 amp battery is only going to provide
50 amps of usable power.
*Group 27 or Group 29
batteries: Batteries are numbered by the external size. Thus
a Group 27 battery will be 12 inches long, 7 inches wide
about 9 1/2 inches tall. A Group 29 battery is slightly
larger. Group 31's are 13" x 7" x 10". The capacity (number
of amps/power) does vary between brands.
I opted for the smaller
Group 27's. The larger batteries are way too heavy for me to
maneuver. The next time I buy more batteries I may chose
larger heavier ones as by then I shall be at the "hire
testosterone" stage of battery replacement. I won't be able to
lift them myself.
Each battery can only
be recharged a certain number of times before it fails.
There are tricks to rejuvenate batts though long term I have
not see a lot of success. It's easier to simply replace.
I do not
have the funds to continually replace batteries.
Calder's tome [Boatowners
Mechanical and Electrical Manual 4th Edition]
recommends we use a smaller percentage of battery capacity.
That will allow more recharging cycles.
Each of my 12-volt batteries holds 100 amps of
power. I want to use the smallest percentage of amp hours possible in
order to have those batteries last. Here's a chart:
use 125 amp hours per day in my life of decadence.)
*I rounded up to 150 amp hours per day in my chart to
account for the extras. Some days I might watch three
movies. Or use the microwave for lots of popcorn while
watching said DVDs. It's always better to estimate on the
higher side for usage.
Trust me when I say we
can always find accoutrements for a more decadent lifestyle. I
have never heard a boater say they had too much power
It is a good idea to have plenty of batteries. It is not just your
solar power generation that counts. We have to have a place to store
the power. That is the battery bank.
How many batteries do you have aboard your boat?
Do you prefer easy-to-digest shorter articles or colossal ones that
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