Modifying crimp terminals?

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BabaYaga

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I have some fairly heavy battery cables terminated by tinned copper terminals similar to these:
Copper Tube Terminals - 50mm² Cable
Terminals have been professionally crimped on.
Because of new batteries without the traditional conical poles, I would now need to modify the stud holes in the crimp terminals by drilling out the present 6.5mm to 8.5mm (to accept M8 bolts).
I realize the tin plating on the inside of the hole perimeter will be lost, but as this is not the primary contact area anyway some minor corrosion developing here over the years should not be a problem?
Or would it?
I would be grateful for any comments.
 
just solder the copper under where you drill out. As long as there is sufficient contact area you're fine. That said, the lugs are cheap and a crimper won't break the bank so I'd consider changing them if cable length allows.
 
Done it many times. If you look at the pic you posted the width of the terminals look the same and the seems wide enough for a 12mm hole so a 8 mm would be OK

The tip of soldering the inside of the hole is a goode'n.
 
Use a good waterproof grease and there really should not be corrosion. It's always good to take the terminalls off and clean them up every 2-3 years anyway, just in case. In fact, the drilled ID is NOT really part of the contact area. Only the faces. And with the solder right next to it, there will still be galvanic protection.

Yes, I've done this a number of times.
 
It is not ideal, but commonly done and does not cause any problems.

Bare, untinned copper lugs are not unusual even in marine applications so the small loss of tin plating around the new hole is not a great concern.

Generally 50x8mm lugs have a slightly larger “foot” than 50x6mm lugs, so a drilled out 50x6mm is not quite the same as a genuine 50x8mm lug, but the difference in contact area is not great.
 
BabaYaga said:
I have some fairly heavy battery cables terminated by tinned copper terminals similar to these:
Copper Tube Terminals - 50mm² Cable
Terminals have been professionally crimped on.
Because of new batteries without the traditional conical poles, I would now need to modify the stud holes in the crimp terminals by drilling out the present 6.5mm to 8.5mm (to accept M8 bolts).
I realize the tin plating on the inside of the hole perimeter will be lost, but as this is not the primary contact area anyway some minor corrosion developing here over the years should not be a problem?
Or would it?
I would be grateful for any comments.
Click to expand...
Yes, I've done it without any long term problems if you apply grease/oil/WD40 of your choice (I use wd40 and have been for decades but some will say their potion is better). Opening up the holes with a twistdrill is not easy as the drill can snatch and distort the soft copper. I find a stepped drill much better Erbauer Step Drill Bit 4-20mm

www.solocoastalsailing.co.uk
 
If you have an M8 taper tap handy, that's good for opening up the holes. As Plum says, a twist drill will grab and there's not much to get hold of. The tread you cut will just strip when you tighten things up.
 
BabaYaga said:
I have some fairly heavy battery cables terminated by tinned copper terminals similar to these:
Copper Tube Terminals - 50mm² Cable
Terminals have been professionally crimped on.
Because of new batteries without the traditional conical poles, I would now need to modify the stud holes in the crimp terminals by drilling out the present 6.5mm to 8.5mm (to accept M8 bolts).
I realize the tin plating on the inside of the hole perimeter will be lost, but as this is not the primary contact area anyway some minor corrosion developing here over the years should not be a problem?
Or would it?
I would be grateful for any comments.
Click to expand...
I would drill them 8mm rather than 8.5mm as the drill will likely make a slightly oversize hole anyway, and most M8 bolts are a tad below 8mm OD, and the copper ring exposed is completely insignificant. But be very careful when drilling them and do not hold them in one hand. When the bit penetrates the softer copper may tear and then the drill bit can violently grab the crimp out of your fingers. Don't ask me how I know this !

A decent hydraulic crimper on ebay is less than £30.

Pull very hard on the crimp to try to pull it off the cable. If it comes off it wasn't tight enough, and I sometimes find with thin walled crimps that using one jaw die a size smaller is necessary. On longer barrelled crimps I routinely double crimp right over the bell mouth section.

Finish with a piece of shrinkwrap and the finished job will look very professional.
 
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