Solder versus Crimp

gregoinc

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Jan 7, 2018
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Hi Folks,

I am at the stage of putting together my battery to invertercabling. I intend on using 70mm2 welding cable as my initial starting point. Before I start attaching lugs on the cable I am interested to know what the general thinking is with attaching the lugs - solder versus crimped?

Would very much appreciate your views, including the pros and cons between solder versus crimping.

Thanks, Mark
 

Redpacket

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You can do both, I did.
I crimped first then soldered (with electronics type resin core flux solder not plumbers flux paste)
 

ozz93666

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70mm2 is on the big side ...works out at 0.25 Milliohms /meter ...

Even carrying 100A the power loss is 2.5 W for every meter of cable that's 0.1% of power transmitted if operating at 24V

.......Carrying 50A ... ............loss is 0.75 W/m

The cable getting hot is never a problem .... it's always the connections ...particularly to inverter.

I think red packet is right , crimp and solder ... make sure the heat of soldering doesn't compromised the connecting surface of the lugs.
 

gregoinc

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So when you say crimp and solder... do you mean doing both on the same lug? If so, how would that be done?


ozz93666 said:
70mm2 is on the big side

Yes, probably more than I need. My theory, I want to run a cable between the battery location and inverter (3-4 meters) that allows me to scale the batteries without the need to change cables. So whilst initially the cable might be large, it will be capable of handling future battery loads. The initial battery pack voltage will be 48 volt from 14S x 5P LEV40 cells.
 

ozz93666

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gregoinc said:
So when you say crimp and solder... do you mean doing both on the same lug? If so, how would that be done?


ozz93666 said:
70mm2 is on the big side

Yes, probably more than I need. My theory, I want to run a cable between the battery location and inverter (3-4 meters) that allows me to scale the batteries without the need to change cables. So whilst initially the cable might be large, it will be capable of handling future battery loads. The initial battery pack voltage will be 48 volt from 14S x 5P LEV40 cells.



@ 48V the % lost will be even smaller so total of8meters will lose 6W @50A delivering 2.4Kw .... probably about the right thicknesscable for a fairly long distance .....

I initially thought crimp , as standard practice,and then solder in the spaces between the wire and lug, I do this , but for smaller cables .. with 70mm2 the heat will be rapidly conducted away , a soldering iron would never do it I don't think , also the plastic on the cable will start to melt ...

crimping seems industry standard on such jobs , so I suppose it's very reliable ...just with soldering too you know it's really connected..

Perhaps just crimping is fine for you, the extra soldering only appropriate for smaller cables.
 

gregoinc

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Re 70mm2... I tend to agree, butI am one of these guys that over engineers the crap out of everything :)

I had seen some YT videos where people used a gas torch to heat the lug, and then melt electronicssolder into the lug, and then slowly slide the cable into the lug with the molten solder inside. That was my initial thinking as I really want to make sure the wire is connected to the lug. I suppose after I've soldered I could always crimp the lug... just to be really sure. Thoughts?
 

Korishan

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If you use the right crimper and proper sized connectors, you won't need to use solder. The crimper should be strong/large enough to be able to fully cold-weld the joints. That's where the hydraulic crimpers come in handy. They can put an enormous amount of force on the compression and basically cold weld the strands and lug into 1 chunk of metal.
 

Minx

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Crimp all your terminals. Use the correct crimping tool for your application. A decent crimping tools for heavy gauge cable is expensive but will ensure proper connection and no heat build up. If done properly there is no need to solder, the impurities in solder will add resistance to the join. Also manufactures only crimp in all applications, have you ever seen solder in a crimped joint!!
 

Ibiza

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Minx said:
Crimp all your terminals. Use the correct crimping tool for your application. A decent crimping tools for heavy gauge cable is expensive but will ensure proper connection and no heat build up. If done properly there is no need to solder, the impurities in solder will add resistance to the join. Also manufactures only crimp in all applications, have you ever seen solder in a crimped joint!!

Agree with Minx no soldering!!
 

farmerjohn

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gregoinc said:
Yep... have been looking at this crimper...16 Ton Hydraulic Crimper

I bought that same one on Amazon for about $100 Canadian

It does an excellent job!! I crimp them twice. Once near the lug and once near the wire. I tested it by hanging the crimped wire from a bolt and then pulling down on the wire with all my weight. No issues!

I also use carbon conductive paste at all my connections

I had a loose connection once and while passing 150 amps at 55v the joint only got mildley warm after a couple hours. Once I tightened it up - it's cool to the touch!

The paste is fantastic for insuring a 100% connection
 

Korishan

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farmerjohn said:
I also use carbon conductive paste at all my connections
...
The paste is fantastic for insuring a 100% connection

URL to the paste you use?
 

ozz93666

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farmerjohn said:
gregoinc said:
Yep... have been looking at this crimper...16 Ton Hydraulic Crimper


I also use carbon conductive paste at all my connections

Ah ... you learn something everyday ... searching this it seems it does work ... many types , silver ...a tube of copper paste on eBay for 3 euros ...claims it helps stop oxidation of the surfaces of terminals ...
 

gregoinc

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ozz93666 said:
Ah ... you learn something everyday ... searching this it seems it does work ... many types , silver ...a tube of copper paste on eBay for 3 euros ...claims it helps stop oxidation of the surfaces of terminals ...

Link to copper paste would be handy :)
 

gregoinc

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Thanks, the copper grease looks interesting. But I suspect the product originally quoted is probably the way to go, given the copper talks about car brake parts, and the MG chemicals product looks purpose made for crimping cables. Thanks for the link :)
 
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