Date: 2 January 2019. Battery Check
and Cheater Method.
Aboard Seaweed I inspect my batteries the first week of each month.
But checking each cell, load testing, and more all takes time. Sometimes I just want the job done. It is important
to do this monthly, at least for folks like me using inexpensive
lead acid batteries from Walmart. After six months of testing I am
confident my "cheater" method is working well. Here's
what I do.
Years ago a good friend used the
word batts as a substitute for batteries when speaking with me. I
got used to it and do the same in real life. As I write the way I
speak, below you will see the word batts used interchangeably with
I am happy when my batteries show 12.75 volts.
Note: first I am going to cover how to properly test
the batts. At the end I'll tell you my Cheater Method.
Yes, I am sure most of you know all
this. It is covered extensively by Real Experts.
Originally I would do the Full-On testing program every month. That
meant I would separate each batt out from the system individually.
Now experts will tell you that you need to do this 12 hours in advance of the testing. That is true,
however this is real life. Batteries power my life so the whole
Perfection Mode doesn't happen aboard Seaweed.
#1) Keep all batteries separate for
the tests. Otherwise you get an average for the voltage. That figure will
not help you isolate and correct any problems.
I wanted to show my multimeter with
the two probes. Ignore the 5.43 number please. (It's an old
#2) The first check for my batteries
is to determine the voltage via my multimeter. I place the red probe
on the positive terminal of the battery, and the black on the ground. By comparing
with the others in my bank I will know how the battery is doing.
Presuming all of
your batts are approximately the same age, they should "wear out"
aka lose their ability to fully recharge at about the same rate.
What I am looking for are anomalies. A battery that is not the same
as the others has a problem.
This was a trouble light
↑ for a car. It originally had a cigarette plug at one end.
Note: I removed the cigarette plug
gizmo and attached alligator clips. In retrospect, I should have
used larger clamps. Instead I utilized what was on hand. They work,
but it could be better. Larger clamps would be easier to attach to
the battery studs.
#3) Next attach a light (power drain) to the battery and watch as
the voltage decreases. For a 1A bulb such as shown above, the
voltage will usually decrease by .5 volts. In other words, the battery
would start at 12.7 volts and while the light is on the voltage will
decrease to 12.2 volts. When the light is removed the voltage resumes the
original 12.7 volts reading.
This is called LOAD TESTING. That
means I am placing a load (power drain) on a battery. Some batteries
will show a full charge and yet not have power available to perform.
The experts will call this a Surface Charge. Surface charges are not
good. There isn't really any power available to use.
Surface Charge for the gals:
You've mixed your cake batter and poured it into a pan. The bowl
still looks full from the side, but there's nothing in it. A similar
thing can happen with batteries. The Surface of the battery plates
will test fine, but when you try to use the power there is none!
What I look for: The voltage on a
battery that is going bad goes down farther and faster than the
rest. I then know I have a problem with that particular battery.
Lead Acid batteries require "topping up" (re-filling
with DISTILLED WATER only) on occasion. A battery that is different from
the rest could be low on fluid. Or out!
This battery had no fluid in the
You can see the plates that store the power are flaking and icky.
The above 12-volt battery was aboard the yacht with the
32-volt system I
on last year.
Details can be found in the
Diagnosing a Bad Battery article.
Measuring the individual cells on
Lead Acid batteries is easy. First remove the
battery cap. Using a multimeter put one probe on the ground post of
your battery. The positive probe is stuck into the fluid of your
battery. Write down the voltage. Do this for each cell in the
battery. The total is the voltage for the batt. Most of the time for
a 12-volt battery I see 2.1 volts in each cell.
there is a difference of more than .2
volts between the cells in a single battery, I know that within
three months that batt will be toast. Each time one cell starts to
go bad it
seems like the rest will soon follow suit.
5 January 2019. My
friend Fred is a genuine electrical guru. He said he would
not use a multimeter to test the individual cells. Instead
he utilizes a hydrometer.
This is my hydrometer:
the hydrometer: Squeeze the bulb with
the smaller tube in the battery acid. The liquid goes into
the top of the hydrometer. Beads inside will float. By reading the
markings, I can tell how healthy the battery is.
problem with a hydrometer for me is that I want to know
the specific number, not a percentage rating. Like my
method of looking for anomalies or differences between the
cells, the hydrometer will provide that information.
Another issue I have
when using a hydrometer is that I seem less graceful with
the battery acid. Too often some comes out of the tube
gizmo. The bulbs do not last forever so if you chose to go
with a hydrometer, be sure to buy a spare.
That said, many folks do prefer the hydrometer. Both
provide information as to the health of our batteries. I'm
not an expert, so will continue to do what I've done for
Aboard the 40'er I grew up aboard we did use a
Hydrometer for many years. Then we switched over to a
multimeter. I do not recall why, though Daddy was a numbers man
too so perhaps that is why he preferred the multimeter. We did
have one particular pair of probes for the battery cells.
The battery acid does damage
the probes during testing. They won't last forever even when
you wipe off the battery fluid immediately. Therefore my
advice should you chose this route would be to pick up a free
Harbor Freight multimeter. Use that unit just for your
Sometimes a person just needs a boat ride. This is
Treasure Island ↓ which is on
the west coast of Florida.
Treasure Island is a pretty area. It was nice to be
underway again after the Red Tide abated.
My musings on red tide algae can be found in the
Red Tide and Forest Fires
Gosh it was good to be underway...
soon I'll have to head over to the American Legion for a visit.
For the record, yes my batteries are all okay now, though there is
one I am keeping my eye on.
Eye Candy, aka another picture from
my recent voyage:
But I digress...
The above battery testing method works very well. It provides precise information for
those who desire it. Sometimes though I simply want the job finished
and without a whole lot of hassle and effort. Here is the Cheater
Method I use aboard Seaweed.
It is important to
regularly check your batteries. When one batt stops accepting a charge,
the automatic chargers will detect that lower voltage. The charger
will keep plugging in power. All your batts can become damaged
because one goes bad.
The Cheater Method
- Battery Testing
One thing that is important to
know is that at this point
I have access to AC power. Thus, it is easy for me to turn on the
breaker for my Battery Charger. I do this (power the charger) two to three hours before
I want to check my batts.
Then I open up the
bilge. I shoot the top of each cell (NOT just the battery or the
studs, the individual caps) and check for temperature discrepancies.
My readings through the bilge for every battery except one was
close to 82 degrees.
Recently I found one batt that was a
lot hotter than the rest of
my bank. One cell showed 102!
That battery got special attention. When I opened the cap I could
see the fluid was low:
The water is down 1" from the top. The plates are
still covered. That means that permanent damage is unlikely.
I topped off the battery with
The following day I rechecked that battery, again
turning on the electric battery charger preceding the test. All was
What you should
know: Heat is ALWAYS bad.
Anytime something is hotter than it should be I
investigate. It is important to figure out why that is happening.
Daddy used to say "Things
don't burn out. They burn up." We always paid close
attention to unusual heat. I believe that is why so many items
lasted us for decades.
To this day, I
check for undue heat when I am running any powered device.
I will stop and allow a tool to cool off before continuing to work
It is entirely possible that I am too cautious when it comes to
using my tools. I rely on what is aboard my boat. Therefore I take
care of what I own. For me that means not overstressing a motor nor
running it hot.
In case you wondered: I write the date of purchase
and warranty information on paperwork. Details on how I keep track
of that sort of thing can be found in the
Warranty Paperwork (SeaSense bilge pump)
This is my
infrared thermometer. You'll note the purchase details written
on the paperwork.
I always remove the 9-volt battery when I put away my
Etekcity infrared gun. Otherwise
the batt will die.
Affiliate link: Etekcity® Non-Contact Infrared Thermometer -26 to 716°F Temperature Gun w/ Laser Sight
Besides my vise grips, the infrared thermometer is my most used
tool. You need one too, especially since they are now in the
$15 range. Remember though when checking batteries to shoot
the caps not the battery itself. That part is very important.
As for me, I will individually check each cell every quarter now
instead of monthly. I am using the infrared thermometer gun every
month. That's my take on the whole battery testing process.
I am posting this specifically for you fellows
without easy access to your battery banks. The Cheater Method has
been tested aboard Seaweed since last summer. The humidity of
summertime was not
conducive to me wanting to spend loads of time in the bilge, in case
Please note that I am not
an ABYC certified expert.
Therefore, follow in my wake at your own
The rest of my
The bad batt,
at 102 degrees
Using the infrared thermometer did detect the battery with low fluid
on one side of the batt this past month. The other side I did open
and it was fine. As an aside, the temperature on the good side was 82 degrees just
like the rest of my battery bank. When I did the full-on test for the new year all
was well, including that battery which needed fluid last month.
My advice is this: Check once thoroughly and then use the infrared gun to monitor
how things are.
To you and yours, I hope to see you
along the waterways.
Thank you for reading.
How often do you check your batteries?
And, have you any other battery checks that you implement regularly?
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In the Bilges,
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