Parasitic battery draw testing info

[paulv]

Here's some useful info I found and hope it can help people. It's essentially an application of Ohm's Law where the resistance of a fuse is known (that was previously measured), and then a voltage measurement is taken across the fuse yielding the current (after checking the chart). Then we can check the specs for what the quiescent current of the circuit should be and compare the values.

This is a good trick and sure beats going out and buying a precision amp clamp probe which are a few hundred bucks for a good one (and beyond my DIY wallet!!).

Regards,

paul...

Vd Chart Inst.pdf

Voltage Drop Across a Fuse Chart.pdf

[JFP in PA]

Here's some useful info I found and hope it can help people. It's essentially an application of Ohm's Law where the resistance of a fuse is known (that was previously measured), and then a voltage measurement is taken across the fuse yielding the current (after checking the chart). Then we can check the specs for what the quiescent current of the circuit should be and compare the values.

This is a good trick and sure beats going out and buying a precision amp clamp probe which are a few hundred bucks for a good one (and beyond my DIY wallet!!).

Regards,

paul...

I'm not sure how this chart is useful. First of all, the fuses are not responsible for the parasitic draw on the battery, the components on the circuit are. Secondly, you don't need a clamp probe to measure parasitic draw (current, measured in mA) which can easily be detected accurately by a $20 multi meter.....................

[paulv]

Here's some useful info I found and hope it can help people. It's essentially an application of Ohm's Law where the resistance of a fuse is known (that was previously measured), and then a voltage measurement is taken across the fuse yielding the current (after checking the chart). Then we can check the specs for what the quiescent current of the circuit should be and compare the values.

This is a good trick and sure beats going out and buying a precision amp clamp probe which are a few hundred bucks for a good one (and beyond my DIY wallet!!).

Regards,

paul...

I'm not sure how this chart is useful. First of all, the fuses are not responsible for the parasitic draw on the battery, the components on the circuit are. Secondly, you don't need a clamp probe to measure parasitic draw (current, measured in mA) which can easily be detected accurately by a $20 multi meter.....................

First: Agree

Second: Agree

The idea is to measure the current draw without opening the circuit to insert the DMM into it. All they essentially did was to measure the resistance of a bunch of fuses and then created a table of voltages to do the Ohm's law arithmetic on to calculate what the current would be going through the fuse that yielded that voltage.

BTW, this was from an article by Karl Seyfert in the Dec 2010 issue of Motor magazine that he got from a Carquest training seminar -- it's nothing that I thought up!

Regards,

paul...