Date: 2 February 2020.
Multimeter Improvement (clamps)
Every boater I know has a
multimeter aboard their vessel. One of my neighbors has one from
Harbor Freight. Although
it was working as intended, I knew I could
make the meter better serve his purposes. My improvement worked, he's
pleased, and now
I want to do the same for Seaweed. Here is how and what I did.
Harbor Freight on occasion offers
coupons to customers for a free multimeter with any
purchase. These units are quite good. They appear to be just as well
made as the one I bought
at Radio Shack all those years ago. I actually have two of the red
One Harbor Freight multimeter is
set aside so when I do electrical work off the boat I can bring it
along. The second is a spare for when either of my primary meters
goes on the fritz. Checking 12-volt DC connections is a regular
occurrence aboard Seaweed.
This is the multimeter from Harbor Freight
that is aboard a Prairie trawler near me:
While chasing down an
electrical issue I wanted to test the main battery bank voltage. The goal
was to verify that the built-in battery charger was properly
working. Although holding the probes to the battery terminals was
was an awkward stretch for me. I wanted an easy method of testing
The cable from a defunct battery
charger was the solution I needed.
First I had to MAKE SPACE
↑ for the probes to
slide into the wires attached to the battery charger clamps.
A while back an inexpensive
portable battery charger had given up the ghost. It was not
repairable. I rescued the two clamps that would attach to the
battery terminals along with the cord that connected to the charger.
The clamps were on a 4' length of
wire. I separated the cord at the end that formerly was closest to
the charger by snipping between the two (positive and ground) wires.
Then I pulled the two sides apart for
approximately one inch.
Those clamps from
the battery charger would of course easily attach to the 12-volt
battery terminals. I also needed to be able to insert the multimeter
probes into the wires from the old battery charger. I used my Pokey
stick to do that.
A pokey stick is what I call a
miniature awl. I have several.
My current favorite is pictured below ↓
starting a hole in the overhead.
Identification: When you see a solid color
wire next to one of the same color with a stripe, the stripe is
usually the positive side.
Colors mean things too. To make
this more complicated, AC and DC power are indicated by different
colors for the three biggies: ground and neutral and positive.
Fortunately none of that has to be known until the job comes up.
Then I get out
Calder's and do as he says.
Testing is shown above. I later made sure the probes fully inserted
into the wires with no exposed metal.
This set with the
clamps was left with the neighbor on his boat. He can use the probes
the normal way for verifying voltage on regular wiring. When
checking on his main battery bank it will be an easy matter to
insert the probes into the wires with the clamps.
I was happy to have solved the problem of how to
easily check battery voltage with the small Harbor Freight
multimeter. Though not fancy, this is a solution that will work for
many of us with smaller boats, limited budgets AND a spare set of
Clamps are relatively inexpensive even at retail
prices. Most of us have 12awg wire that can be utilized for this
project. Better yet, the next time you spot a battery charger by the
dumpster you will now have an idea what to do with those clamps.
Stay warm, and thank you for
I'd love to hear what criteria you find Absolutely
And, have you picked out one particular brand and size that suits you?
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In the Bilges,
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