Battery Holders and their Metal Contactors

I was wondering, are the contactors that are on the battery holders nickel plated, tinned or silver? I'm guessing nickel.

Which is better to have for conductivity, nickel, tin or silver?

If they are nickel plated, and tin is better or silver, how hard would it be to strip off the nickel and put the tin or silver on it?


I ask because we want to minimize as much loss as possible (especially for those of us who are building packs with removable cells; not soldering them in place) and each transition from one metal to the next causes a certain amount of loss.

The tabs on the holders are easily removed, so could it be done where you take the tabs and put them in some kind of acid bath to take the nickel off, and then put them in another solution to tin/silver plate them?

Hrmmm.....

Probably tinned. Since they're very cheap, nickel and silver would be too expensive compared to tinned copper. I only have one for an 18650 now, and it's tinned copper according to the seller.

Ok, so that makes conductivity better than silver. Not as good as nickel (I'm guessing). Was just curious in case I might need/want to have my tabs redone for resistance.

Well actually, the resistance of copper is lower than nickel, but a bit higher than silver.
Here's something about this:
https://www.bluesea.com/resources/108/Electrical_Conductivity_of_Materials

Ok, gotcha, Thnx BlueSwordM. I was wondering if I had gotten the silver/nickel backwards and I did.

Ok, so Silver Plating is better than bare Copper. And nickel is way down the list. However, Tin is further down the list, though. Hrmm

Silver.........105%
Copper.......100
Gold.............70
Aluminum.....61
Nickel...........22
Zinc.............27
Brass...........28
Iron.............17
Tin...............15

So instead of Tin coating, we should use Nickel if possible. Of course, if we could harvest enough gold from bust electronics, we could do gold plating That'd make for an interesting powerwall build.

Personally, this is why, in large projects, I would prefer to use soldering instead of spot welding: you cab use copper by soldering, which means your system can become quite a bit more efficient.

Well, yes and no. Copper has to be connected via solder, which is mostly Tin. Whereas a Nickel strip is 1.5 times more conductive than Tin. So, a Nickel strip should theoretically (i say this cuz I'm not 100% sure) have less resistance and thereby less power loss.
Now, if we could spot weld Copper to Copper, that'd make a huge difference. Or Copper to the cell, which is Nickel (right?).

Heheh, or maybe for those who want removable cells, spot well little Nickel posts on the ends of the cells

What you are saying is interesting. I should do some more research about it, and some experiments of copper vs nickel.

Nickel won't corrode like copper and silver. So many contacts are copper or brass with nickle coating. When I worked in electrical system design we specified gold contacts for low current applications. The contacts were copper with nickel coating and then gold was selectively plated on top of the nickle to keep the connection clean.

As far as resistance goes you need to eliminate disimilar metal corrosion. We did this in high current frame connections by bolting the battery cables to a threaded boss that had a stainless steel plate welded to it. The steel boss was then welded to a steel frame.

In the case of the battery holders, if they are nickle plated steel contacts with copper wires soldered to them, they should make good contact with the battery. The batteries appear to be nickle plated steel.

The holder contact has to provide enough spring force to maintain contact. Steel makes good springs.

As far as resistance goes, if you have sufficient cross section area, then the resistance will not be an issue. The soldered connections are the best, because the connection is spread over a bigger area. In the case of our recycled 18650 batteries, we get a lot of sharp nickel strip shards that turn the connection into a point contact in a holder. These can become hot spots if you are pulling a lot of current. That's why you see multiple spot welds in most all of the connections In laptop and especially drill battery packs.

So with the cells being nickel plated, and the tabs being nickel plated, then it should really be ok as long as there is sufficient force.

Interesting. I didn't think about the solder spreading out over a larger contact area. This in turn negates the weaker transmission. Kinda like having 1 4" pipe (copper) and 15 1/2" pipe (solder). It more than makes up for it by having more pathways.

Thanks egam That's why we love EE's here