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Homemade Amp Meters

How to make a 2,000 amp DC amp meter for less than $20

Build a 2,000 amp dc amp meter and learn to make a very easy and inexpensive dc ammeter shunt.

When I first installed my 3 solar panels, I wanted to be able to see how many amps I was pulling through the inverter. Watts would have been nice too. But all I had was my charge controller and it only showed amps going from the solar panels to the battery bank. I knew that I could pull up to 3,000 watts (6,000 for a short time) with my inverter. That's 250 amps or short peaks of up to 500 amps. I just didn't have an ammeter that could go that high. The only thing I had was a cheapo multi-meter that only measured up to 10 amps.

Later, I was working on my Wind Power & Battery Systems book and I needed to measure amps to the battery. So, I purchased an analog 25 amp meter. It worked fine until we had a nice little windstorm. It seems that 25 amps x 12 volts is 300 watts and my windmill was producing about 800 watts. Needless to say, the meter didn't work very well after that. I then purchased a 1000 amp digital meter with shunt from China. It worked fairly well until I hooked up a small power supply to it so I didn't have to use the double A batteries. It was fried also.

Well, later on, I was working on my Welding with Batteries book when I needed to measure amps while welding. I knew it could be up to about 400 amps or so. I started looking into making a homemade shunt so I could just use a cheap multi-meter with it. After several months of research and trial and error, I had achieved more than I had set out to do. I not only made a shunt work with my meter, I found that I could use certain materials and easily make one to handle up to 2 - 3,000 amps. I also could use it with any cheap multi-meter (I use a little $11 meter).

I also discovered that I could use many different metals such as zinc plated steel, steel coat hangers, copper wire, aluminum, stainless, etc. But the length of the shunt material was difficult to compute. There was different resistance for the different metals. Continuous amps were computed differently depending on if the conductor was insulated or not. It was also affected by running the same conductor in parallel pieces to increase amp ratings. Temperature also affected things.

So, that is when I came up with the Shunt Designer program. It would allow me to select the thickness of the conductor, metal type, number of parallel pieces, temperature of the conductor, etc.

It would compute how long each metal conductor in the shunt should be in inches and meters. It would also compute the max continuous amps the shunt can handle based on if the conductors are insulated or not.

I include this great program free of charge with the book download.

I then learned another trick (which is in the book) that allows me to flip a $3 switch and my cheap multi-meter shows Power in Watts coming from a 12 volt battery bank. (this could be modified for 24 or 48 volt systems) I can flip the switch back and it will go back to amps.

So, to reiterate, with this program and e-book, you can do the following:

Make a 2,000 amp shunt and amp meter for under $20 (actually can be 3,300 amps by making one little change)
Make a (500 amp / 6,000 watt @ 12v) amp and power gauge for under $25 (This can be scaled up to 24v or 48 v battery banks)
You can even use existing wiring in your system as a shunt
You can measure the current draw in your renewable or backup system
You can measure the current coming from your windmill or solar panels

You don't need electronic skills to make the shunt. And you don't need to take your meter apart. You just hook up the test leads to the shunt. You can even use little alligator clips to do this.

This e-book is 11 pages in full color. And the book and Shunt Designer program are in a "zipped" file about 300 KB in size. You will need a PDF viewer to view it and winzip to open the unzip the two files. Upon ordering, you will be shown a download link for instant download of the ebook and the program .

$14.95 USD

Now you can pay with Paypal