Stainless steel bolts and nuts for battery terminal connectors

[s0larcuriosity]

I want to replace the bolts and nuts on my Lead acid battery terminals. All the local stores sell stainless steel ones and I've read about them having low conductivity. What material would you guys recommend?

 

[BentleyJ]

The bolt should not be the main conductor in a connection. In other words, the bolt is used to hold the cable lug directly against the conductive surface of the battery or bus bar or other device. Washers should only be used on the top of the lug NOT between the lug and the contact surface.

Copper and Silver are the best electrical conductors with aluminum coming in 3rd at 40% less than Copper. Everything else like Brass, Bronze, Lead, Steel and Stainless Steel are only about 25% as good as Copper.

I would go with SS bolts.

 

[RCinFLA]

I want to replace the bolts and nuts on my Lead acid battery terminals. All the local stores sell stainless steel ones and I've read about them having low conductivity. What material would you guys recommend?

Bolts and nuts should be for connection lug flat surface compression, not for carrying current.

You want strength. Copper nut can strip threads easily.

A good strong flat washer on top of stack helps distribute the terminal surface compression force to achieve best electrical connection.

 

[s0larcuriosity]

Only one side of the lug touches the terminal directly, so if the bolt and nut have good conductivity would it not increase the surface area for current flow?

 

[BentleyJ]

Yes, but Copper or Aluminum bolts are difficult to find and Copper especially is too soft to hold torque.

 

[Tomthumb62]

Only one side of the lug touches the terminal directly, so if the bolt and nut have good conductivity would it not increase the surface area for current flow?

IF you’ve sized your wire appropriately AND you’re using high quality parts, including thick solid copper lugs (tinned coated or not) with good solid cold weld crimping , then that single side connection is all you need. If you’re relying upon conductivity of the bolt and washer, then you’re doing something wrong, ie have taken an unsafe shortcut.

 

[Gold Country Russ]

I would use silicon bronze bolts and either silicon-bronze or stainless steel nuts. Both are easily purchased from McMaster-Carr www.mcmaster,com

 

[Vigo]

The only advice i have to give about stainless (which i do think is the default and perfectly good choice here) is to carefully avoid overtorquing them. They seem, in my practical experience, to be much more sensitive to thread galling and thus seizing and needing to be cut off to salvage the stud (rarely done by me, too much effort, but im not going to twist off a stainless stud made into a battery if i have any other choice). So, ive picked up the habit of using antiseize and ‘less casual’ torquing practices on my stainless-to-stainless threaded connections.

 

[Gold Country Russ]

Cheap stainless steel fasteners suck, yes they love to gall whenever it is stainless to stainless. I have had many SS threads gall before actually starting to tighten. With premium 316 fasteners a liberal coat is SS anti-seize is usually adequate. For cheap SS fasteners I have found that glass bead blasting the male threads was very helpful. I worked a lot with SS heat exchanger tie bolts that were frequently tightened and loosened, were expensive, large diameter, and frequently up to 4 or 5 feet long. For those I found that bead blasting the tie-bolts, SS anti-seize, and using silicon bronze nuts was the long-term solution.