Wednesday, June 12, 2024

Measuring Resistance of Fuses with a Milliohm Meter and Kelvin Clips -3- (More 12 Volt Fuses)

I received more 12 fuses and in this this blogpost i am going to present the results of the 12 Volt fuses. My intention was to publish after my post about the 250V glass fuses some evaluation of the data. However i received from Aliexpress a nice Anderson Powerpole connection block "DC 36V AP-8S 8 Channel Power Distributor For HF Radio Communication Power Supply Splitter Anderson Powerpole Screw Fixing" with more 12 Volt fuses. 

As i only had a few results of 12V fuses in my first post about the car fuses and i was curious about these Chinese fuses i gave more priority to measure the 12V fuses.

I want to do a separate blogpost about a review of this Anderson Powerpole block (and it also will appear in a mailbag blog) as i think it is a real nice power block that i bought for a decent price.  Not only does did it had a set of fuses in the block, also a spare set of fuses was included. 
So i now additional have 2 x ( 1x 40A + 3x 25A + 2x 15A + 1x 10A + 1x 5A ) fuses.

In the table below are also the results from the set car fuses already mentioned in the previous blog about the 12 V car fuses (= S1 [set1] ) and the fuse that came with the single fuse holder (= H1)

The measurement with this single fuse holder are not included as i wanted to focus this post on the fuse not on the fuse holder(s). 

Resettable Fuse Circuit Breaker

Via Aliexpress i also got a 12V 24V DC Car Truck Audio Resettable Fuse Circuit Breaker 30A Circuit Breaker. (see picture below) 

Resettable Fuse Circuit Breaker

A nice thing about this fuse is that you can reset it and it can be used as circuit breaker. ('Resettable Fuse Circuit Breaker'). I was curious about this fuse so i ordered one and included the result in the table below.  Pressing the circuit breaker and resetting the fuse (several times) gave each time the same resistance.
Spoiler alert: Relative to the other 30A fuse the resistance seems higher. However the resistance is still low.

Safety

Be aware that these resetable fuse circuit breakers (and also the normal 12V car fuses from AliExpress) have a bad reputation and can be unsafe.

The Carpoint fuses that i did buy at the Gamma  in The Netherlands are also made in China. (See packaging bottom right). 

Measurement

I removed fuses (one by one) from the Anderson Powerpole block and measured the resistances ( Ab to Ab7 [the number corresponds with the number on the Anderson Powerpole block ] ). I was a little difficult to remove these fuses. 

The spare fuses that came with the Anderson Powerpole block ( Ax to Ax7 ) where also measured.

The results

Table 1: Results 12V fuses (Including previous results, sorted on rated current). 
Fuse Color Rated CurrentMeasured
Resistance
Calculated
Voltage drop
at 100 mA
Calculated
Voltage drop
at rated current
Calculated Voltage drop
at rated current in %
relative to 12 Volt
Ab7 Biege 5 0.014 0.0014 0.070 0.58%
Ax7 Biege 5 0.013 0.0013 0.065 0.54%
S1 Brown 7.5 0.009 0.0009 0.068 0.56%
Ab6 Red 10 0.006 0.0006 0.060 0.50%
Ax6 Red 10 0.006 0.0006 0.060 0.50%
H1 Red 10 0.007 0.0007 0.070 0.58%
S1 Red 10 0.006 0.0006 0.060 0.50%
Ab4 Blue 15 0.004 0.0004 0.060 0.50%
Ab5 Blue 15 0.004 0.0004 0.060 0.50%
Ax4 Blue 15 0.005 0.0005 0.075 0.63%
Ax5 Blue 15 0.005 0.0005 0.075 0.63%
S1 Blue 15 0.004 0.0004 0.060 0.50%
S1 Yellow 20 0.003 0.0003 0.060 0.50%
Ab1 Clear 25 0.002 0.0002 0.050 0.42%
Ab2 Clear 25 0.003 0.0003 0.075 0.63%
Ab3 Clear 25 0.003 0.0003 0.075 0.63%
Ax1 Clear 25 0.003 0.0003 0.075 0.63%
Ax2 Clear 25 0.003 0.0003 0.075 0.63%
Ax3 Clear 25 0.003 0.0003 0.075 0.63%
S1 Clear 25 0.002 0.0002 0.050 0.42%
Resettable
 Fuse Circuit Breaker
 (*1) 30 0.004 0.0004 0.120 1.00%
S1 Green 30 0.002 0.0002 0.060 0.50%
Ab Amber 40 0.001 0.0001 0.040 0.33%
Ax Amber 40 0.001 0.0001 0.040 0.33% 

Summary

Higher rated fuses seem to have a lower resistance.

Between 12 Volt fuses of the same rating is not much variation in the resistance.

The 30 A Resettable Fuse Circuit Breaker seems to have a higher resistance (and higher voltage drop) than a standard 30A 12V fuse.

Also, compared to the 250 Volt fuses in my previous post these 12V car fuses have a much lower resistance !!!

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