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Old 03-15-2010, 11:23 AM
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bustedbenz bustedbenz is offline
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Join Date: Feb 2007
Location: Lexington, NC or Boone, NC
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Originally Posted by JHZR2 View Post
It sure seems to me that if when completing the circuit via an ammeter, if you are seeing .4A, then you have your culprit.

Frankly, id replace battery first and foremost. Given that it has gone through a bunch of discharge cycles, IMO it is not reliable anymore, especially capacity-wise. So Id put a new one on (first testing it with your meter to see what a relevant reading should be), and see what that does. If it goes flat, then charge it with a battery charger and put in the old one until you find the solution.
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.

"What could possibly go wrong?"

~Michael S.~ -
1986 M-B 300SDL, retired due to rust and electrical problems. Donated engine to:
1987 M-B 300SDL, odo dead. New project.
1982 M-B 240D, odo stopped at 308,000
1982 M-B 300SD, 175,000
1989 Dodge Ramcharger, 87,000 - 4wd, 318
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