Hammer-driven battery cable crimper, cable lugs, inverters

[artfd]

I had to look long & hard for this tool when I was wiring a 1500 W inverter into my truck. The big #2 and #4 cables that can feed an inverter like this can be purchased with pre-crimped terminals, but the assemblies are expensive compared to the cost of the materials, plus you are limited to the dimensions you can buy. Home Depot sells a rather stiff #2 and #4 cable, and crimp-on lugs for #4, electric supplies sell all kinds of lugs.
The cheapest tool you can buy to crimp battery terminals to this size cable can be purchased from Fastenal, which has branches all over the country. It's $19 at this time, I bought it at Christmas for $12. It takes a couple of weeks to get to you.
There are lugs you can hammer on directly, for $9 each.
Lastly, there are aluminum lugs that fasten to cables with set screws, for $1-2 each. They tend to have rather small mounting holes & their dimensions may not allow for use on some battery and inverter lugs.
The best quality inverters I have seen come with built-in cable receptables complete with set screws, you simply slip in the bare cable and tighten down the set screw, no lugs or terminals of any kind are necessary.

[jeep_bluetj]

The crimp-on lugs are also quite easy to solder on. I tend to crimp them a bit with a hammer in a chunk of angle (kinda like the $20 tool, but alot more redneck....)

Then I stick the lug in a vice, heat it up with my propane torch, and fill the sucker with solder. (use electrical solder, not plumbing solder). If I'm in the mood to care about appearance, I'll stick some heatshrink on the terminal to make it look nice.

Takes me all of 30 seconds or so to put on a lug.

[artfd]

The use of solder in attaching lugs to power cables is controversial. I have 200 amp service to the circuit breaker box in my house, and there is no solder in the lugs that connect those cables to the box, they are either crimped or screwed together. I think the National Electric Code specifically rules out solder in those connections. Some specification writers insist that no solder be used in high amperage DC circuits. Some say that soldering at least keeps water & corrosion out of the lug.
Here's an elegant approach to soldering lugs for those so inclined.

[jeep_bluetj]

The reason NEC says not to solder, and some say it's not a good thing is that massive current could heat the joint to the point that the solder melts. (Tin and lead don't conduct as well as copper, and can heat under current) This would be very bad dripping around inside a box, and then there'd be significant additional heating and arcing inside the lug. All of this would be somewhat less than optimal, what with the resulting fire and whatnot.

On 12v circuits, I'm of the opposite mind. If I get a reasonable mechanical crimp, soldering the joint prevents the oh-so-common corrosion and adds a bit of current carrying capacity. The original copper-to-copper connection is still there.

Maybe I should think about using fluxless silver-based solder as it'll conduct gangbusters... Wonder where I can get 800A or so to destructively test without burning down my house....

[artfd]

I'm thinking of pretty sizeable currents for these cables, on the order of 110A to feed an 12VDC inverter delivering 1100W, that's where I think the solder might break down. The inverter itself should never be in an environment where moisture or vapors causing corrosion would be a concern. I don't see any reasonable technical objection to crimping a lug firmly and then soldering it. In this case the solder would serve more to occupy the air space to prevent any possible corrosion forming inside the lug.

[nawlinsteardrop]

Just one thought, most of the higher end inverter install kits use wlding cable. The stranded type carries electricity better and it is super flexible and easier to install.

Just FYI...

[McTeardrops]

Visit a welding supply place, and you can generally get leads made for the cost of materials. Braided rather than solid, for more flexibility too!

Lenny

[cleonard]

While not exactly tear drop related I do have a data point that might help with the solder vs crimp for high currents discussion.

The basic reason for not soldering is that copper conducts electricity about 7 or 8 times better and your typical lead/tin solder. The other issue is probably the mechanical strain from temperature cycling.

I have a 94 Jaguar XJ6. the battery is in the trunk. There is a big 3/0 or so positive wire that goes to the front of the car for power distribution. It also has a short one foot or so piece that connects the negative battery terminal to the metal of the car body. It is also about 3/0 and has crimped on terminals on both ends.

I was having terrible problems with the transmission computer initializing badly at startup. I tried everything. Eventually I found that the issue was voltage drop in that ground lead. First I tried "recrimping" with various tools. It helped a little, but not enough. Then I broke out the propane torch and flooded both crimped ends with solder. Problem solved. I'm sure the problem was corrosion related and the solder flux must have taken care of that. It conducts several hundred amps at startup just fine.

My conclusion is that soldering is OK as long as it's crimped to some degree as well.

[MikeIA]

Harbor Freight now sells a hydraulic crimper for #12 through 2/0 lugs...on sale right now for $49.99

[artfd]

Being compulsively specific, I post the details
Hydraulic Wire Crimping Tool
Harbor Freight ITEM 66150-0VGA
Ram travel: 3/8"; Maximum crimping force: 8 tons; Crimping range: 0-0.45"; Die sizes: 00, 0, 2, 4, 6, 7, 8,10 and 12; Overall dimensions: 12" L x 2" W x 7-1/4" H
Weight: 5.1 lbs.