Date:  2 February 2020. Multimeter Improvement (clamps)

© janice142

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 meters.
 

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 doable, it was an awkward stretch for me. I wanted an easy method of testing those batts.
 

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.

 

Wire 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.
 

Side Note: 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. Happy hunting.
 

 

Stay warm, and thank you for reading.
 

I'd love to hear what criteria you find Absolutely Imperative.
And, have you picked out one particular brand and size that suits you?
 

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