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Old 03-15-2010, 11:36 AM
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vstech vstech is offline
Join Date: Mar 2006
Location: Mount Holly, NC
Posts: 26,389
Originally Posted by bustedbenz View Post
What am I missing here? Shouldn't connecting an ammeter directly to the + and - of a power source essentially be using the meter as a short-out between the poles (similar to laying a wrench across the battery terminals and producing a welder)? I stuck an ammeter into a household AC power strip one time just out of curiosity and ignorance. The result was that the meter tried to create a dead short between the two prongs, the resultant heat melted my positive meter lead, the power strip (one of those 6-outlet things) was fried instantly and the household breaker tripped. Isn't putting an ammeter across a dc battery causing the same effect (or at the very least, not a reliable measurement) or is this a different principle? If I'm dead wrong here then forgive me for interrupting the thread, but that seems... odd to me, unless I've missed something major. I'm not an electrical person either.

Measuring volts across a battery's + and - I understand perfectly. But I was under the impression that it was impossible to do so on an amp setting.
yeah, only do this with the key off and everything turned off on the car...
even headlights will fry your meter...
setting the meter to ma and leaving the neg cable on the battery, and hooking the meter between the battery and the positive cable will show what the clock, and anything else running is pulling. it should be around 25ma...
500ma (.5A) is a LOT
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