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Old 11-27-2012, 08:43 AM
robertobaggio20 robertobaggio20 is offline
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Join Date: Oct 2009
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Mein Auto: car
Quote:
Originally Posted by BMWFatherFigure View Post
RB - You're punching above your weight. You remove the battery terminal and connect there so you can see when the current drops. If you prod about in the fuse box you COULD accidently hook accross a live pin load and then watch all the smoke come out of your ammeter set at 300ma. Pulling fuses out will not INCREASE the drain current - prodding the the fuse box - not a good idea.i
ok I have worked this out.

1. You would have to be negligent to hook across a live pin load that is large enough to fry your dmm but small enough not to do so if hooked in series with the battery. In fact, I can't really imagine how that would happen actually.

If you are worried about frying your dmm :

a. DMMs are fused, usually to 10A. They are fairly easy to dismantle and access the fuse if you need to replace it.

b. However, that is inconvenient and if you are still worried, then simply get a 5 or 7.5a car fuse, and tie it to one of your leads with pvc tape or even some gel or white silicone sealant, and use the other end of the car fuse as one lead while interrogating the fuses in the fuse box. Takes 3 minutes to set up. This fuse will burn way before the 10A internal fuse is triggered, and is much easier to replace.

c. When you connect your dmm to both ends of an installed car fuse, you are creating a circuit in parallel. Assuming that circuit is carrying current at the time, and depending on your ampere setting on your dmm, the internal resistance of the dmm changes accordingly, allowing very little current to flow through it anyway. So you can't burn out your dmm. The car fuse idea listed earlier is unnecessary, but its a painless precaution to take so why not.

In the interests of transparency, the bentley manual refers to the slow battery terminal method to identify current leaks.



rgds,
Roberto
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