MG Chemicals 847 Test

[upnorthandpersonal]

I'm posting this as a response to a comment from Paul F. Note: mR == milliOhm.

Hypotheses I proposed: MG Chemicals 847 can lower the resistance in a connection between bus bar and battery terminal, especially in cases where limited torque can be exerted, or where the two connections are not completely flat.

Test procedure: Take two bus bars (plated copper) and join them together in one joint with a nut and bolt so that maximum overlap is achieved. Do this with a torque of 4Nm, and repeat this both with and without MG Chemicals applied at contact area on the same set of bus bars. Measure the resistance using a YR1035+ 4 wire meter, positioning the leads at the same location each test.

Resistance of individual bus bar, measured end to end between the holes: 0.06mR, therefor an ideal bus bar twice this size would have a resistance of 0.12mR.


Illustration: test set-up with MG Chemicals applied

Results:

• Without MG Chemicals: 0.22mR
• With MG Chemicals: 0.17mR

Conclusion: The resistance added by the joint without MG Chemicals is 0.05mR higher than the same joint with MG Chemicals applied. Therefor, MG Chemicals can decrease resistance of imperfect joints.

Limitations: I do not have time to repeat this test with additional bus bars, material types, and connections at the moment.

 

[John Frum]

What is "mR"?

 

[upnorthandpersonal]

milliOhm

 

[HRTKD]

I know you said you don't have time to retest, but it would be interesting to see how No-Ox-ID compares. I don't have the resistance tool you do, otherwise I would be out in the garage trying this myself.

 

[John Frum]

This would be something to try for slightly rough or pitted surfaces perhaps.

 

[upnorthandpersonal]

I have done this in the past - I just don't have the results readily available. This was just a quick test for Paul. I will try to make time to do a larger test with comparisons to other compounds such as No-Ox stuff. It just gets more complex because with No-Ox you want to use very little while with 847 it doesn't really matter, which also means that with rougher surfaces it's better to use 847 since it can fill the gaps and improve overall connection.

 

[Sanwizard]

I know you said you don't have time to retest, but it would be interesting to see how No-Ox-ID compares. I don't have the resistance tool you do, otherwise I would be out in the garage trying this myself.

No-Ox-ID on my battery terminals is around twice the resistance of MG Chem based on my tests using MG Chem 8463.

 

[HRTKD]

From the MG Chemicals webpage:

846 – An economical, silicone-based, carbon-filled, conductive lubricating grease. Resistivity of 114 Ω.cm. Broad service temperature range of -50 to 200 °C

8463 – A silicone-based, silver-filled, conductive lubricating grease. Broad service temperature range of -50 to 200 °C. [no resistivity specified, but I'm assuming it is the same or better than the 846 above]

8481 – A silicone-free, carbon-filled, conductive lubricating grease. Resistivity of 160 Ω.cm

847 – A silicone-free, carbon-filled, conductive, non-lubricating paste. Resistivity of 23 Ω.cm

Here's a review of No-Ox-ID and Noalox from 2010 by Practical Sailor.

https://www.practical-sailor.com/wp-content/uploads/2020/02/PS0710_wirecorrosion.pdf

 

[curiouscarbon]

thank you for publishing this test

clearly, it worked

 

[John Frum]

Does the MG Chem 847 prevent oxidation on aluminum terminals?

 

[upnorthandpersonal]

Does the MG Chem 847 prevent oxidation on aluminum terminals?

Yes, it has a corrosion inhibitor.

 

[zolee]

8463 – A silicone-based, silver-filled, conductive lubricating grease. Broad service temperature range of -50 to 200 °C. [no resistivity specified, but I'm assuming it is the same or better than the 846 above]

8463A - Silver Grease​

• Resistivity <0.2 Ω·cm
• Thermal conductivity 1.0 W/(m·K)
• Improves electrical connections between irregular and pitted surfaces
• Prevents arching, pitting, hotspots, and welds
• Inhibits corrosion

It has 100x times better electrical conductivity than the 847

 

[upnorthandpersonal]

8463A - Silver Grease​

• Resistivity <0.2 Ω·cm
• Thermal conductivity 1.0 W/(m·K)
• Improves electrical connections between irregular and pitted surfaces
• Prevents arching, pitting, hotspots, and welds
• Inhibits corrosion

It has 100x times better electrical conductivity than the 847

But it's way more expensive and really doesn't make a difference in practice.

 

[zolee]

But it's way more expensive and really doesn't make a difference in practice.

Well, for 10x more you get 100x less

(This sounds weird without including words money and resistance)

 

[charlesrg]

@zolee the 8463A lists as Grease and the 847 as assembly paste. I don't think it's best practices to put grease directly onto the terminal as it can come undone with vibration. I guess if you're careful to avoid the threads it can work.
I just ordered some 847 from laddresearch as they are cheaper than amazon even after paying the $13 shipping.