Battery Charger Poles

[arturo7]

I was given a battery charger that has no clips or markings on the cables. How can I determine which side is positive?

thanks

 

[66HertzClone]

I would think a DC voltmeter would work. Connected incorrectly a digital meter would indicate -voltage, correctly just voltage.

 

[mech-tech]

Hook a digital volt meter to it. If ya have the positive on the negative, then the meter will show a negative sign on the display.

 

[arturo7]

That was easy.

thanks, fellas

 

[RedBKM]

If you have an analog meter (Simpson 260 etc.) you wont see polarity. You can check each lead for a short to the case, if it's metal.

 

[andywander]

If you have an analog meter (Simpson 260 etc.) you wont see polarity. You can check each lead for a short to the case, if it's metal.

What? Analog meters will indicate polarity.

 

[metaleltr]

What? Analog meters will indicate polarity.

This is the meter he referenced, which appears to show no signs of indication polarity.

 

[andywander]

The polarity indication consists of which way the needle moves.

If you hook it up backwards, the meter needle will be egged against the zero volts stop.

 

[RedBKM]

We understand that but the OP might not. +12 or -12 wont appear and could confuse somebody. I've had to look twice at my 260 more than a few times.

Checking for a short to the case doesn't even require powering it up.

 

[andywander]

We understand that but the OP might not. +12 or -12 wont appear and could confuse somebody. I've had to look twice at my 260 more than a few times.

Checking for a short to the case doesn't even require powering it up.

Well, I don't think we know what the OP understands or not-and I think it is good to explain it, like we have now done, instead of saying something that could easily be misunderstood, like analog meters don't indicate polarity.


And, what makes you think there will be a short to the case on either lead?

 

[bobtheman04]

And, what makes you think there will be a short to the case on either lead?

The negative should be grounded to the case.

 

[andywander]

I just checked 2 different battery chargers.

The first has a plastic case, so neither lead is grounded to the case.

The second one shows infinite resistance between either the negative lead or the positive lead to the metal case. Interestingly, when I powered it up, I did read 14V between the red lead and the case.