A case for mil spec battery terminals

[cranetruck]

This should be of general interest, the matching of battery terminals to cable lug to cable.

Note how the 1/0 cable is connected to the battery clamp, it's tin plated and the opening in the lug is 3/8, like the bolt in the clamp and the outside dia matches the outside of the barrel of the clamp. The lug will not get deformed when it's tightened for maximum contact area.

The assortment of other clamps in the image may not be the best representation of what's available commercially, but you should get the idea....lots of compromises.

(I'm messing with the battery/starting circuit on the 8x8 and just wanted to share)

 

[Elwenil]

Interestingly enough, NAPA carries the military spec terminals under part number PHI 8619 and similar ones that are also mil-spec under NW 728222 and NW 728223.

 

[gimpyrobb]

In the civy applications, I have used car audio battery clamps because the "standard" battery clamp(like in your pic) lacks. I got a few military clamps from one of the bone yards I visited and they do make a difference.

 

[Elwenil]

One clamp I have always loved to use, and now I'm having trouble finding a pic is a "military spec" terminal from NAPA that uses a 4 bolt "cap" to hold the wire in the terminal. The wire can be inserted from 3 directions and it's a really heavy clamp. Too bad I can't seem to locate any anymore.

 

[cranetruck]

One clamp I have always loved to use, and now I'm having trouble finding a pic is a "military spec" terminal from NAPA that uses a 4 bolt "cap" to hold the wire in the terminal. The wire can be inserted from 3 directions and it's a really heavy clamp. Too bad I can't seem to locate any anymore.

Clamping a wire is nowhere near to compare to a properly done crimp or solder connection. Strands will separate and corrode. Perhaps it's a good thing that they are not available.

 

[sprucemt]

Clamps

Interesting thing about the genuine issue military battery clamps that I sell, are that they weigh more than the look alike clamps. Go figure.

 

[cranetruck]

Re: Clamps

Interesting thing about the genuine issue military battery clamps that I sell, are that they weigh more than the look alike clamps. Go figure.

May have something to do with material compatibility for minimizing corrosive action, battery post to clamp to tin-plated lug....

Component parts appear to have been selected for a current draw of 250 to 300 amps max, that is the rating for the cable, slave connector and possibly, the starter motor on an average day with fully charged batteries.

 

[papercu]

clamps

Wouldn't all mil-spec terminals meet the same requirement?
The "look alike clamps" do they claim to be mil-spec? Wayne

 

[Elwenil]

RE: clamps

The ones I posted claim to be mil-spec. They even list the spec number:

Complies with MIL SPEC A521425 - 1/A52425-2

But who knows exactly what that means or if they truly do conform to that spec. Here's a link to the terminal on NAPA's online Truck Parts catalog:

http://www.napaonline.com/NOLViewer/Pages/Detail.aspx?R=13540&ShowPics=1

 

[Elwenil]

Clamping a wire is nowhere near to compare to a properly done crimp or solder connection. Strands will separate and corrode. Perhaps it's a good thing that they are not available.

While this is very true, I still liked them on my old Ramcharger since it's electrical system was in a constant state of flux with me experimenting with different multiple battery setups, alternators, and a lot of accessories. They made it easy to add or subtract accessory wires at the battery without doing a lot of extra work. Plus I kept the clamp coated with dielectric grease to keep the corrosion at bay.

As far as I am concerned, the best, most reliable, fool proof battery clamps I have seen are like the ones pictured below. Get the right clamp for the size of cable, and you slide the clamp nut over the cable, stick the cable in the clamp, and tighten up the nut. I prefer them since you don't have to solder or crimp them which can be hit or miss for the average guy without the right tools and equipment.

 

[Elwenil]

Ah ha! I finally found a pic of the old 4 bolt clamps I used to have on the Ramcharger. Note that the top plate of the clamp is lead, just like the rest of the clamp. The bolts screw into nuts that recess into the bottom of the clamp so you don't have to worry about stripping the threads out of the soft lead. They weren't perfect due to the issues Bjorn spoke of, but for my uses and multiple batteries, lights, winches and other accessories up to 2 Ga. cables, they worked pretty well. The listing says they will work with 6 Ga. to 4/0 Ga. cable.

 

[sprucemt]

Re: clamps

Wouldn't all mil-spec terminals meet the same requirement?
The "look alike clamps" do they claim to be mil-spec? Wayne

The ms # was marked on the commercial terminal. They were approx 2 oz - 3 oz less in weight than the genuine issue ones that I carry.
As far as I am concerned there is commercial mil-spec and then there is the real mil-spec. There is vast difference or sometimes complete difference in a product. Clothing is a real issue.But that is another story.

 

[cranetruck]

.....
As far as I am concerned, the best, most reliable, fool proof battery clamps I have seen are like the ones pictured below. Get the right clamp for the size of cable, and you slide the clamp nut over the cable, stick the cable in the clamp, and tighten up the nut. I prefer them since you don't have to solder or crimp them which can be hit or miss for the average guy without the right tools and equipment.

Cast copper is compatible with the copper wire in the cable, but not the normal lead posts on the battery. A difference in temp coefficient can possibly create problems.
My local NAPA will crimp my cable lugs to spec, at least they say so, haven't used that service yet.

 

[DDoyle]

Here is the "Mil-spec" for the battery terminals, and a later revision. While not the case in this instance, be wary of the "Mil-spec" branding for a couple of reasons.

Without giving a spec number, the claims are truly meaninglyless. You can paint a Toro lawnmower CARC according to the finish spec, and claim its "mil-spec" - but that doesn't make it a good lawnmower - only that it has a good paint job!

Secondly, some of the specs cover multiple variations of an item, which may or may not fit your application.

Regards,
David Doyle

 

[cranetruck]

Isn't it nice to have this kind of info available, thanks David!

Note that the nuts and bolts are to be zinc chromate or lead covered, not cad plated, all to reduce corrosion.

What's the mil spec on the battery if I may ask, MS35000-3, perhaps the terminal alloy is specified?

 

[Elwenil]

Another thought (and this may be considered blasphemy) is this, Mil-spec might not be the best thing out there. For restoration, sure the mil-spec stuff is the way to go but lets face it, mil-spec is good, but it's made by the lowest bidder and what was high tech 40 years ago is a bit behind the times now. This really doesn't apply much to battery terminals but for other electrical items, we have come a long way. Some improvements aren't all that great, like the push button style light switches that seem to have quality issues but then again that could be a case of the lowest bidder again. For other items, I'll take a modern relay over an old mil-spec one any day as well as the new weatherpack connectors over the old rubber military ones. Just a few thoughts.

 

[emmado22]

I can attest to the fact that the ones the Spruce Mountain sells are the "real deal" US GI MIL SPEC ones... Not "wanna bees"

 

[cranetruck]

....I'll take a modern relay over an old mil-spec one any day as well as the new weatherpack connectors over the old rubber military ones. Just a few thoughts.

I shouldn't, but how is a "modern" relay better than an old military hermetically sealed one made for the full mil spec temp range, g-exposure etc or how is weatherpack connectors superior to the silver plated rubber protected Packard ones?
Like I said, I shouldn't, but I'm just the opposite, I rather use the old mil spec ones. Have you looked at a typical relay used in the VIC-1 intercom amplifier lateley? Gold plated pins.......
We are playing with very expensive toys, perhaps they were built by the "lowest bidder", they still had to meet the specifications.
Another bad example are flasher units, compare new and old and see where you end up.

About the battery terminals, if they are made with exact alloys to eliminate corrosion, how can you improve on that?
Some things, like the CTIS, is not even good for the full mil spec temp range, lots of compromises in today's products.....

 

[DDoyle]

What's the mil spec on the battery if I may ask, MS35000-3, perhaps the terminal alloy is specified?

Not being lucky enough to own a M656 series truck, I dunno if this is really what you want. MS35000 is for the 2HN battery. MS52149 is the spec for the 6TL used in most 5-ton trucks.

So, here are both specs.

HTH,
David

 

[surpdlr]

Re: Clamps

Interesting thing about the genuine issue military battery clamps that I sell, are that they weigh more than the look alike clamps. Go figure.

Just of confuse things, I have run across lead plated copper Military looking terminals from surplus......... They were used in some tracked vehicles. Even found then with cooling fins on them!!