Does this mean I have a bad cell in my 48V system?

[42OhmsPA]

Almost anything serrated works better than not.

Agreed. The Nord Locks go above and beyond with the opposing cams on the washer mating surfaces.
You would not want to use a serrated nut them.

 

[chrisski]

I don’t like click torque wrenches for low nm; I prefer analog gauges.

I tried serrated washer over serrated nuts, and I don’t like that.

It gets tighter until it climbs over to the top of the tooth and then quickly drops off. Made me feel like I was tightening too much and it would snap.

 

[Skypower]

@Skypower
They aren't the cheapest but I've used Nord Locks in high heat and vibration (exhaust manifold / turbo) successfully after I tried every other option besides safety wire.
I see no reason they wouldn't work for a battery application.

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

L?L ! My first build used Nord Locks. Firstly none of the nuts have ever backed off, it seems that things below have moved or the threads/studs have stretched. The nut with Nord Lock washers could torque down some more as well, but dear lord the torque required to remove them was double! Pucker time. Definitely better than any other lock washer I’ve used but I don’t see an advantage for this application and probably a very high risk for terminal thread stripping or stud breakage if removed.

 

[Dave911]

Are the battery terminals aluminum? If so, in the electrical power business, shining them up and coating them with Noalox to prevent the formation of aluminum oxide is common. Aluminum oxide is a good resistor. Passing high currents through a resistive junction will heat it and loosen nuts. That was part of the issues with aluminum house wiring in the 70's and 80's. I lived in such a house and the wires kept coming loose from the outlets due to repeated heat/cool cycles. It was really bad. I had to replace several outlets in the early 80's, shine up the wires and coat the wires before attaching them to the new outlet. Once that was done the issue did not reappear. Fortunately that was a rental house. We moved out and left that mess behind.

 

[Skypower]

Are the battery terminals aluminum? If so, in the electrical power business, shining them up and coating them with Noalox to prevent the formation of aluminum oxide is common. Aluminum oxide is a good resistor. Passing high currents through a resistive junction will heat it and loosen nuts. That was part of the issues with aluminum house wiring in the 70's and 80's. I lived in such a house and the wires kept coming loose from the outlets due to repeated heat/cool cycles. It was really bad. I had to replace several outlets in the early 80's, shine up the wires and coat the wires before attaching them to the new outlet. Once that was done the issue did not reappear. Fortunately that was a rental house. We moved out and left that mess behind.

You’re on the right track. No-Ox-ID A special or marine green grease( a synthetic) is actually a bit better than something that contains a conductive metal or carbon in it for our terminals anyway. (Edit; not on threads!) Noalox is best used for a structural’s wiring systems when called for.

 

[#40Fan]

Buy some 1/4"-20 studs in the length that you need. They'll sell tap themselves into the old stud hole.

 

[Skypower]

Buy some 1/4"-20 studs in the length that you need. They'll sell tap themselves into the old stud hole.

Thread forming like that is something that I hope I never have to resort to, but yeah, it’s been done. The striped 6mm hole would be about .245” The hole size for a 65% thread for thread forming is .235. As a guess, a grub screw would get about a 35% thread but it would be a net fit. That’s taking into account that it starts well and threads in straight. I’ve got no clue how strong that would be.

I’d be looking at a 1/4-20 Heili coil at that point because I’ve got the kits. Sacrifice one tap and grind it back to make a bottom tap to get the lead to the bottom of the hole after the first tap. You can cut the coil to the exact length you need with a thin dremel disk. A piece of metal strapping material slid between the coils helps holding the coils and protects the coils from cutting through. Since it’s a blind hole you would need to use a pick to break off the tang at the bottom. Done it many times but not on a battery.

 

[Berseker]

That does happen.

You can try to retap them to a bigger size or helicoil them.

what size of helicoil is ok for normal eve 280ah terminal?

edit @Skypower could you post the link of where you bought yours

 

[Skypower]

My Helicoil kits are older than half of the population. I’d just look up Amazon and look up the reviews. A lot of nice combination kits. Two sizes will work 6mm or 1/4-20. The kits will have a tap size drill, tap, install tool and tang knock out. You must be very careful not to drill any deeper than the existing hole. The drill will have a tendency to “grab”. To reduce the problem I would probably get another drill as same size as the kit’s and remove some of the drill’s hook or lead angle to about only 1 to 3 degrees with a diamond hone/file. Just a small land a seen by the shiny spot. It would be best if it’s not done freehand but the cell put in a cushioned vice that’s bolted down in a drill press or milling machine. Extreme caution!