Checking amps

mbalbritton

mbalbritton

#@$%!
Joined
Mar 22, 2005
Location
Lakeland, FL
Is there a way to check the Amps on a car battery with a digital multimeter?

As a self proclaimed no nothing when it comes to electronics, what do I need to know about car… or if it matters, my boat batteries, and determining if they have the cramping amps I need?

I’ll get into the long story if needed, but back to the simple question I started with. Thanks.
 
You'd need to put a load on them to check amperage. The auto parts stores will usually test batteries for free and generally give you a nifty little print out of the results.
 
No. I have a Harbor freight battery load tester for this purpose.
 
Depending on the multimeter …yes it’s possible.
But not as easy as testing voltage. You’d have to disconnnect a lead and test in series ….and your leads and meter will need to carry the requisite current.

Want to see the amp drain your radio or seat heater uses- no problem. Want to see it while cranking? Gonna need a more specific tester
 
I have a Fluke 376 clamp on ammeter in my box at work. It does AC and DC, I used it when I was sizing my fan circuit when I was wiring my buggy. It's good to I believe 1k amps DC. If you had access to something like that you could use it to measure the CCA. But otherwise just take it to Advance, etc., or buy a cheap tester like this.

Amazon product ASIN B000AMBOI0
 
I have a small tester from HF. It will give you volts, run through a test cycle and give you the CCA's Also, before you actually do the test, you put in the CCA's from the label of the battery. And then run the test. So far, I can't say it's completely accurate, but I have found it to be at least close, and reliable. The one I have is a little different than this one, but does the same thing.
www.harborfreight.com

12V Digital Battery and System Tester

Amazing deals on this 12V Digital Battery And System Tester at Harbor Freight. Quality tools & low prices.
www.harborfreight.com www.harborfreight.com
 
mbalbritton said:
So it’s a load test thing and not just as simple as testing voltage.

Thank you.
Click to expand...
It depends on what you are looking for. If you want to know how much load the vehicle is pulling, you will need a high soot ammeter. If you want to know how many amps the battery can handle under a true load, you’ll need a battery load tester. If you want to kind know how much life it has left and the voltage, a battery tester like the one @upnover linked will get the job done.
 
Ugh…

4 batteries in my boat 3 of which tested bad.

2 Batteries Plus Duracell Marine Group27 for House and Cranking. Cranking battery is dead

2 Deep Cycle Marine Interstates for trolling. Both dead.

Boats suck.
 
mbalbritton said:
So it’s a load test thing and not just as simple as testing voltage.

Thank you.
Click to expand...
Eggs Zachary.

Here's my favorite analogy intended for the non-electrician.

Imagine that a battery is a crateful of tiny little oompa loompas that are anxious to get out and do some kind of work. One useful metric is how anxious they are to get out - voltage. Another is how quickly they are going to run out and do some work for you once the door is open - current (amp).

Measuring voltage is easy. You basically just ask the oompa loompas how excited they are to get out. They give you a measurement of potential. If it's really high they're going to do everything that they can to bust out as quickly as possible, even if that means blowing s*** up in the process. If it's low they are only slightly motivated and only a small amount of work is going to go into getting out. If you ask too much it just won't happen.

Asking how quickly they are going to get out isn't really a fair question because it really depends on the size of the door that you open up and the size of the hallway they have to run down in order to get to their work site, and how much work is waiting for them on the other side. If you open a really small door they are going to go as fast as they can but it's still not going to be very fast because the hallway is just too small, and if they get there and there's no work to do they're going to be pissed. Only enough we'll go to get the job done and no more. If you open a giant door and have a huge work load on the other side then a whole bunch are going to run out all at once and get you a ton of work done.

But the point is in order to get that measurement, you have to actually measure how quickly they will run through the hallway based on the size of the hallway and how much work you're giving them to do in the first place. It's not as easy as just asking them how fast they'd like to get there.

Resistance by the way is just the size of the hallway ;-).

And it sounds to me like you need a replacement set of oompa loompas that are a little bit more motivated
 
Battery tenders and running it regularly definitely helps.

If they sit for a long time, they sulfate. Don't let them drop below 12.4 volts!
 
mbalbritton said:
Ugh…

4 batteries in my boat 3 of which tested bad.

2 Batteries Plus Duracell Marine Group27 for House and Cranking. Cranking battery is dead

2 Deep Cycle Marine Interstates for trolling. Both dead.

Boats suck.
Click to expand...
B.O.A.T
Break Out Another Thousand.
 
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