Can I Read How Many Amps Are Being Used W/ A Multimeter?

[tlukasavige172]

I have this multimeter http://www.kleintools.com/catalog/multimeters/electricians-multimeter and I'm wondering if there is a way to read how many amps my trailer is using with the lights turned on? I am in the process of switching all the bulbs to LED and I would like to know how many amps are being used prior to switching and then taking another reading after switching them over. I have a battery bank consisting of 4 batteries that all the lights are running off of. Any advice is appreciated. Thanks

[a_dog]

Just saw this... I have a Belkin watt monitor, but you could just get one of these & plug it inline with your shore power, then turn all your lights on & write down the total watt usage. After you swap your bulbs, check the total watts used with your lights on.

[tlukasavige172]

Thanks a lot for all the replies, I've definitely learned a lot from this post. I ended up using the meter I have and disconnecting the battery cable and putting the meter in series with it. Out of the 42 lights, I have 11 switches so I was able to work up to the lights I was worried would be over 10 amps. As long as I didn't turn on more than one switch at a time I never hit the 10 amps. Thank you again.

[Puddle_Pirates]

Probably the easiest way to do this, without burning up a 10 amp meter is to locate your panel/fuse box. Place you meter in 10 amp mode. Remove 1 of your 12 volt fuses from its place in the fuse box. Set the fuse aside. Touch one lead to one side of the fuse holder, and the other lead to the other side of the fuse holder.

Now your meter is in series with the current flow and will show you the amps for that circuit. You can check individual circuits this way. If you want to check individual lights or equipment on that circuit remove the light, or shut of the equipment and note the difference.

If the circuit you removed the fuse from has a fuse rating of more than 10 amps you take the risk of blowing the fuse in your meter. Of my fuse box, only 1 of 15 has a fuse of more than 10 amps.

This way you can check individual circuits and get an idea of what each circuit is using. Total them up if you want to know total amp draw.

[junmy3]

You could always ask other campers to show you how to take a reading if they know how. Most would be glad to help you.

[tlukasavige172]

Thanks BurbMan. I may just get a different multimeter as that would come in pretty handy.

[BurbMan]

tlukasavige172 wrote:
With this other style that is being recommended where do I connect it?

That ring opens up like this:



Then you just put it over the positive or negative battery cable like this:



You can wire the meter you have now between the positive cable and the battery and get the same reading. BUT your meter maxes out at 10 amps, so at 1.5 amp per bulb, 10 bulbs =15 amps, and you blow the fuse in the meter before you can get a reading.

The clamp on type that Roy suggested is good because you don't have to disconnect any wiring, you can easily take readings at any point.

Here's a YouTube Video on how to use a clamp-on meter.

[enblethen]

Depends on what you are looking for.
If you are trying to find a parasitic type load then start at the 12 volt DC power distribution panel. Most parasitic would or should be under the 10 amp.
If you are trying to determine how much you are using normally then connection on the main battery cable would be best, then pull each fuse in the dc panel to see what loads are on that circuit.
If there is enough slack in your DC panel you could connect there, but may not be able to connect to the feed into the DC panel.

[2oldman]

Or you can just forget about it and use this close estimate:

1.5____ Single 1141 lamp
3.0____ Double 1141 lamp
.05____ Single LED clearance light
.18____ LED spot light on USA flag

[korbe]

I used my cheap meter and it worked well at letting me know how many amps each of my 12-volt things used. I would only turn on, then off one item at a time so not to max out the meter.

And yes, disconnect the positive, then connect the meter to the positive battery terminal, and the other prong to the cable you just disconnected.

[tlukasavige172]

enblethen wrote:
OP:
The meter you posted requires it to be placed in series with the load. It is rated at 10 amps. I would guess that a lot of the 12 volt DC loads could be in the range of 30-40 amps, which would burn out the meter.
This type of meter can have what is called a shunt. The meter would then be connected to the shunt to get a reading above 10 amps.
On a clamp on style amp meter the cable or wire being tested goes through the ring on top of the meter. It would then read the ampacity. Very easy to use.
Most clamp-ons have the same function as a multi-meter.

Thank you very much for the explanation, it was really helpful. I'm a bit confused on where I should be connecting it. With the multimeter I have I was thinking I would disconnect the positive wire from the batteries and connect the multimeter between the two. With this other style that is being recommended where do I connect it?

[enblethen]

OP:
The meter you posted requires it to be placed in series with the load. It is rated at 10 amps. I would guess that a lot of the 12 volt DC loads could be in the range of 30-40 amps, which would burn out the meter.
This type of meter can have what is called a shunt. The meter would then be connected to the shunt to get a reading above 10 amps.
On a clamp on style amp meter the cable or wire being tested goes through the ring on top of the meter. It would then read the ampacity. Very easy to use.
Most clamp-ons have the same function as a multi-meter.

[tlukasavige172]

Okay I'm starting to get a little confused but I'll research a bit and see if I can clear this up some.

[enblethen]

Yes, this one would be better suited for all needs then the OP's meter.
Roy"s meter from Sears

[RoyB]

Go to SEARS and look at their CRAFTSMAN CLAMP ON AC/DC ampmeter. Cost around $60..

Looks like this


They also make a AC model only that looks the same so be sure to get the one that measures AC and DC up to 400AMPS...

These are great for measuring DC CURRENT at the +12VDC battery cable.

Top measure AC AMPS you will have to clamp around the BLACK CABLE coming in from Shore Power. The best place to do this is at the AC POWER DISTRIBUTION PANEL where you remove the front panel and clamp around the single BLACK wire coming from the main circuit breaker.

Roy Ken