Keeping a positive + attitude

[jagwinn]

Hello All!,
I found a battery charger in a tractor shed. It is one with a slide switch for 6 or 12 volts... I would like to get it back into usable condition but there is one thing that has me stymied... Someone needed the battery clips and cut them off...
Now what I need to know is how do I determine which is the + and - wire????
Thanks,
John
PS, was sort'a shocked with the new appearance of the forum... It says I'm a new member [joined 2013]...??

........just to keep it interesting...

 

[Professional Tool User]

A multimeter will allow you to figure out which end is which.

 

[jagwinn]

Thanks! negative reading indicates red + probe is touching - side?

 

[kelpaso1]

Not understanding what you are doing. Put the red probe from your multimeter on one wire and the black on the other. If you get a positive voltage reading you have it correct. If its a neg reading you have it backwards.

 

[Professional Tool User]

Guess I was wrong in assuming you were 100 percent sure about what I hinted at. Plug in the charger and turn it on. Touch each cable with one multimeter lead. Set the multimeter to DC volts and select the 20V range if yours isn't auto ranging. If you have the polarity correct, a digital multimeter will give you a positive voltage reading. Your positive lead will be contacting the positive cable and the negative lead the negative cable. If you have the ends mixed up, your voltage reading would be negative. If you are still not confident about the procedure, test it out on any battery you may have that still has a charge.

 

[rharman]

Member status will be updated down the road a bit. There is a good thread from Ryan's post on the home page following all the issues, requests, etc. on the new site.

 

[jagwinn]

Thanks Pro tool, I did figure out what you meant through experimentation. Yes, I have a Craftsman Automotive multi-meter; digital, and it showed the difference switching probes made. Got it all together now and charging.
Thanks for you help!
John