12.5v when testing ground to to neg battery post

[BananaDan]

when I connect my multimeter to the negative battery post (neg cable disconnected) and a body ground I see 12.5 volts. Shouldn't I see close to zero?

[Charger-Bodie]

Is the door open ? Turning on the dome light?

[BananaDan]

No, the negative battery cable is disconnected (see above).

[A383Wing]

you will see 12v...your meter is connecting the battery to ground, that is, the meter is now your neg battery cable....it's measuring a voltage that is being used, such as a dome light, radio memory, anything that takes 12v to run.

Bryan

[BananaDan]

Thanks Bryan. Makes sense.

[elacruze]

Keep in mind that your DMM can't see current, so you could have a minute parasitic draw and show full battery voltage. Clocks, interior lamps, radio memories can all show up on the meter. If you're trying to find how much draw there is, use a test light-if it glows bright, you need to find out why. No light or very very dim isn't enough to worry about if you run it every week or so. 1 amp or less is acceptable.

[c00nhunterjoe]

Even the cheap $5 multimeters from harbor freight have an amp setting. Make sure the key is off and doors closed, hook the meter up in series on the 10 amp setting between the post and the cable. .05 amps is the industry standard for allowed parasitic draw, but the old chargers with the clock MIGHT be a little higher. If you have more then 1/4 amp then there may be a draw.