Procedure to check output of 12v battery charger?

[TWIH]

It's a manual charger, so it is essentially a transformer with multiple secondary windings, and a rectifier.

Not much there to test, really, and the built-in meter should indicate something close to max (2 or 10 amps) if you hook it up to a somewhat depleted battery. 

On these two lower settings, you could insert your DMM (in 10 amp mode) inline, and measure the amps, which should roughly agree with the ampmeter on the unit.

I never really got the multimeter wires/prong in line correctly, at least that’s what I think. I was fooling around with the jump pack with the battery still in its case, and just trying to use the booster cable clamps for connections. Works for reading voltages just fine but not current.

I read up more on the web and on Amazon, this one would work but at $45 its more than the price of the charger, duhh...
Signstek UT210E digital clamp meter, AC DC, 177 reviews 4.5 rating...
Here’s a sample rating:

“Accurate and easy to use
October 23, 2015
Verified Purchase
When I looked at this I was skeptical but I figured that for the price it was worth the risk so I clicked "BUY". Now that I have had a chance to use this tool I know that it is accurate and easy to use. I mainly purchased this to measure DC amps with the clamp. It works just as well as my well known brand name units do but I like this much better. The probes are very well made and very high quality. The meter readings are stable and match the readings of my other devices I know to be accurate. It also comes with a nylon case which is not mentioned anywhere in the description. The back-lit display is a really handy feature and you can leave it off to conserve battery if you don't need it. It also has non-contact A/C voltage detection so you really only need this tool in your pocket and your in business. I use the DC amp clamp to chase down parasitical drains and this really makes short work of most cases. It measures as low as 0.001 amps. The voltmeter is auto adjusting and it also includes an OHM meter and capacitance measurement. It is extremely simple to use and it's small size makes it very practical. This is a keeper and one of my favorites.”

[tx2sturgis]

Ok, question:

When you hook this manual charger to a battery, does the built-in meter move like it should?

If so, it's working and most likely operating normally.

I peronally would not spend $45 just to verify and calibrate what is showing on the built-in meter. 

Now, if you really NEED that amp-clamp for other tests, then sure, go ahead.

[sternwake]

Good that you noticed the one clampmeter only read AC amps.

I have the red cen teck, and an older yellow one and their voltage readings do drift in time. there is a small potentiometer inside for calibration.

The clampmeters are also capable of many of the same functions as most DMM's and are good to have anyway.

you can clamp them over either single wire in a circuit it does not have to be the red

Tp read amps on the cen tek and most multimeters one has to move the ground probe or positive probe to the other recptacle and run current through its internal shunt.

I honestly do not trust the analog ammeters provided on chargers after having used the clampmeter and seeing highly different readings on at least two chargers.

But I agree with Tx, its a lot to spend to just verify the charger is working, but if you need want an extra tool a DC clampmeter is more useful than a DMM. and if all you want to do is measure how much the charger is putting into any battery it is hooked to, then the wattmeter I previously linked counts the amount of current over time, rather than instantaneous current readings and is much more useful, and cheaper, and is pretty easy to splice inline, but ithe 50 amp engine start setting setting will overheat the wires in about 30 to 45 seconds, if the battery can actually accept 50 amps. the 130 amp rating is for very brief durations only

I have a craftsman clampmeter model at least 7 years old, no experience with any other clamp meter and will make no recommendations or type opinions on products i have no personal experience with. This product isinaccurate wit Nimh batteries inside, it requires regular alkaline AAA batteries

[TWIH]

Thanks for the replies. Yes the 0-100% guage needle swung all the way over to 100%, verifying what I already knew, and telling me that “something” was working. Wether it was actually trying to output 2 or 10 amps I dont know, likely since the battery was “full” it wouldnt have accepted much more than half an amp anyway, regardless of the setting.

This whole thing was just based on my watching the guys YT video where the same kind/style/age Centek charger on 2 amps was outputting about 2.25 a and the 10 did nothing but buzz at first, then the red Centek cheapie multimeter needle swung back and forth and settled down at about 5 amps.  

I had been “blissfully ignorant, living in the land of the soothing green light” with my older 8/2 Schumacher and never even considered what it was outputting.  

Why manufacturors won’t include a basic amp meter on the charger like they did in the past, IDK. Surely they don’t cost that much. True the average joe wouldn’t know what it meant but the rest of us would be glad. I mean, just how accurate were the amp meters of the 50’s, 60’s and early 70’s cars, back before they just went to “idiot lights”. They may not have been calibrated well but they did give one a clue...

Back under my rock I go. 

[sternwake]

The ammeter which came with my 89 dodge van barely ever moved, and one time when my alternator failed, i did not notice it was 1/16" inches below center instead of 1/16" above center. A voltmeter would have made it obvious no charging was occurring, but the way I noticed it was my windshield wipers moved extra slow.

I might have access to a 10+ year old HF charger in the next month or so, I'll try and test output.

[TWIH]

That would be an interesting test. Maybe your old Schumaker unit as well.

I had a 70’s Ford that the amp guage axtually worked reasonably, it was a -15 to + 15 style and would respond to the minus side due to a slipping alternator belt or a heavy electrical load.

I suppose a lot of us make presumptions about what electrical appliances are actually doing, such as these chargers. Maybe it.s “much to do about nothing”.