Improving Contact Area on Welded Stud Pads

[Browneye]

The ones I got that match the ring terminals for 22-24g may well be 4mm. I'll try tapping one, can re-do my balance leads. I never liked those 1/4 ring terminals under the stud nuts.
Would be a good opportunity to apply some ox-gard to everything anyway. And I'll be putting on the new tinned terminal leads for the main +/- terminals.

 

[noenegdod]

I wished they were copper at first, but after doing the calculations and recognizing that I didn't have to deal with galvanic corrosion at all, I decided not to gild the lily. They'll do their job fine.

I was in the same boat. I really wanted to use copper and was trying to figure out how to deal with galvanic corrosion and finally realized that it is just so much simpler and reliable to just use aluminum.

 

[EcoRV]

Removed reply to keep thread on original topic.

 

[Horsefly]

I was in the same boat. I really wanted to use copper and was trying to figure out how to deal with galvanic corrosion and finally realized that it is just so much simpler and reliable to just use aluminum.

I have a couple of thoughts on the galvanic corrosion risk, and they may not apply to everyone.

First, my install is in a very dry climate, in the mountains of Colorado. The install is in the basement of a cabin. There's not much electrolyte available, which is necessary for galvanic corrosion to occur. I realize that many folks are putting systems on boats and in higher humidity homes, so that's different.

Second, it isn't difficult (and in fact it's kind of fun) to nickel plate copper. Even with the low humidity, I decided to go ahead and plate my home-made copper bus bars.

If you are also putting some GB Ox-gard or MG Chemicals 847 (better) between the bare copper and aluminum, I would think that also would reduce risk of galvanic corrosion, but maybe someone here is more of an expert on that.

 

[jsmetalcraft]

I just added a bms and top balanced a pack of CALB cells that I have had in a 12v battery for four years. They were in a storage compartment of a camper. The buss bars are bare copper. The negative terminals are copper, maybe copper coated aluminum, and the positive terminals are aluminum. They are just as clean as they were 4 years ago. I question that corrosion is such an issue that many are worried about.

 

[triplethreat]

I just ordered a package of these.....thank you for posting them. And yes....a "tight" 6mm but that is what small rat tail files are used for. I had just started to order some on Amazon, but they looked pretty rough and likely some sanding/honing would have been required, not to mention that they were 1/4" and the inside diameter was .265. These will fit like socks on a rooster.

UPDATE....I ordered these washers Wed. afternoon and they just got dropped off by UPS.....less than 24 hrs after ordering them. And the even better news......they fit right on the welded on 6mm studs on the battery......zero filing......and YES, they do fit like socks on a Rooster!

 

[noenegdod]

I have a couple of thoughts on the galvanic corrosion risk, and they may not apply to everyone.

First, my install is in a very dry climate, in the mountains of Colorado. The install is in the basement of a cabin. There's not much electrolyte available, which is necessary for galvanic corrosion to occur. I realize that many folks are putting systems on boats and in higher humidity homes, so that's different.

Second, it isn't difficult (and in fact it's kind of fun) to nickel plate copper. Even with the low humidity, I decided to go ahead and plate my home-made copper bus bars.

If you are also putting some GB Ox-gard or MG Chemicals 847 (better) between the bare copper and aluminum, I would think that also would reduce risk of galvanic corrosion, but maybe someone here is more of an expert on that.

For sure! Im all in on doing what works for you and even just doing what you want to do simply because you want to do it. For me, there is a high possibility of condensation. Im mobile, and live in a cold climate. I will do as much as I can to mitigate the possibility that the battery will ever be colder than the surroundings and keep the batteries environment as dry as practical but for me there is a distinct possibility of humidity.

Personally, having tried the 847 I now prefer this: https://www.digikey.ca/en/products/detail/chemtronics/CW7100/307001 MG chemicals has a silver grease but is not recommended.

 

[Hedges]

Second, it isn't difficult (and in fact it's kind of fun) to nickel plate copper. Even with the low humidity, I decided to go ahead and plate my home-made copper bus bars.

Now if you can figure out out to tin plate the aluminum terminals, I think you'll really have something.

 

[Horsefly]

Now if you can figure out out to tin plate the aluminum terminals, I think you'll really have something.

Yeah, that ain't happening!

 

[Hedges]

Would Alodine work well enough?

 

[Horsefly]

Would Alodine work well enough?

Interesting question. I'm following. This could destroy a whole cottage industry that has grown up on this forum!

 

[Browneye]

I used 4mm screws, which seemed perfect for the relatively small balance leads. In my case I have two leads for each: BMS and Active Balancer. I think the 4mm screws would work fine even with your thinner copper bus bars.

Exactly right. I actually got SS M5 screws and tapped the busbars - worked out very well. Everything is solid, everything is coated with oxgard. I used half of one single layer bus bar and put those on the main terminals, put a nylock on those leads. The other three balance leads cinched up nicely in the double-layer busbar. Thanks for this tip!

I re-crimped balance leads - I have some 22-26g crimpers in my RC toolbox. Shrink and SS screws and spring washers. All the busbars got oxgard. Removed the digital meter for the cells - the BT app is better than I had hoped so it was redundant. That simplified my top wiring by 50%.

@triplethreat at was kind enough to sell me a handful of those special little aluminum washers from McMasterCarr - they are not very big but certainly much bigger than the little post by itself. They worked perfectly! Thanks for this tip! I used 360grit paper on the terminal tops, then oxgard and the washers. Bus bars on top, then the serrated nuts. Now I wished I had used SS nylocks.

Buttoned'r up and charged to 14.2 - still a couple of runners so discharged them and the bms balanced everything at 3.55/cell.
I'm happy with the way it works and the amount of juice it will make. The chargers are all working well, and the smart shunt meter is really handy and easy to calibrate.

Test tap - used SS instead of zinc screws. These 230A bars are pretty small. 120A bms.



Two with washers, the rest just the post - size comparison of mating surface:



I never liked the balance lead ring terminals under the busbar nuts - this solves that.

 

[Hedges]

Plexiglass on the end, holding the BMS?
Looks like another sheet of that (or some other insulator) covering the bolts and metal plate would be nice to have, for when you're wrenching on the fuse.
Unless you only use box end for that.

Rotating fuse holder 90 degrees and mounting it to the plexiglass as well would also keep wrench away from metal, assuming that orientation is accessible.

 

[Frick]

Exactly right. I actually got SS M5 screws and tapped the busbars - worked out very well. Everything is solid, everything is coated with oxgard. I used half of one single layer bus bar and put those on the main terminals, put a nylock on those leads. The other three balance leads cinched up nicely in the double-layer busbar. Thanks for this tip!

I re-crimped balance leads - I have some 22-26g crimpers in my RC toolbox. Shrink and SS screws and spring washers. All the busbars got oxgard. Removed the digital meter for the cells - the BT app is better than I had hoped so it was redundant. That simplified my top wiring by 50%.

@triplethreat at was kind enough to sell me a handful of those special little aluminum washers from McMasterCarr - they are not very big but certainly much bigger than the little post by itself. They worked perfectly! Thanks for this tip! I used 360grit paper on the terminal tops, then oxgard and the washers. Bus bars on top, then the serrated nuts. Now I wished I had used SS nylocks.

Buttoned'r up and charged to 14.2 - still a couple of runners so discharged them and the bms balanced everything at 3.55/cell.
I'm happy with the way it works and the amount of juice it will make. The chargers are all working well, and the smart shunt meter is really handy and easy to calibrate.

Test tap - used SS instead of zinc screws. These 230A bars are pretty small. 120A bms.



Two with washers, the rest just the post - size comparison of mating surface:



I never liked the balance lead ring terminals under the busbar nuts - this solves that.

i See what ya did there. It’s nice, I’ve done nearly that same treatment in the past and even went with conducting silver paste for corrosion resistance and perfect contacts.

my Current pack I decided to go way easier and simpler. The little crimps were a pain to source, and crimp and ring could add miniscule resistance to a bms lead. So I just stripped the wires with my thumbnail and soldered each one. Hold a bic lighter under the buss bar, and use a soldering Iron on the wire, nice easy connection. My bus bars when removed from the battery loom like a new age wind chime. Works like a dream. Was free, took 15 minutes. Then again, I solder nearly every connection, I just like how perfect the connection is and how long it lasts. I even soldered the crimps onto my mc4 connectors. I’m nuts like that. 4/0 battery cables, oh ya, flooded with solder. Run ice cold at full amps.

just my style.

 

[Browneye]

I come from a history of soldering connections as well. The latest crop of technicians frown on it. When aviation says 'no soldered connections' ya gotta sit up and take notice.

 

[Browneye]

Plexiglass on the end, holding the BMS?
Looks like another sheet of that (or some other insulator) covering the bolts and metal plate would be nice to have, for when you're wrenching on the fuse.
Unless you only use box end for that.

Rotating fuse holder 90 degrees and mounting it to the plexiglass as well would also keep wrench away from metal, assuming that orientation is accessible.

It's lexan - polycarbonate. I'm limited on height - the clearance is 10-1/2" and I'm 10-1/4.
Rather than try to fit the bms to the side of the cells, I chose to mount it to a lexan sheild/front plate. The tension bars are in the way - yes they have an acrylic tube covering.

Metal plate on top of the terminals? Really?

The front part of the base was extended to accommodate the class T fuse - the holder is screwed down there. If the cover is off of the terminals, the battery is disabled. Yes, a box-end wrench.

 

[Hedges]

Metal plate on top of the terminals? Really?

I was referring to the metal plate which is part of the BMS. And the lugs/studs on the BMS.
From the perspective of an earlier picture, and before you mounted that meter, it looked to me like a socket + extension used on the nuts of the fuse could contact it.
So, I suggested a sheet of plastic covering the studs, also covering the metal plate, of the BMS.

Installed where you have it, maybe rotating fuse holder 90 degrees and mounting it to same lexan sheet as BMS would make fuse more accessible and keep wrench away from the other metal parts.

 

[Frick]

I come from a history of soldering connections as well. The latest crop of technicians frown on it. When aviation says 'no soldered connections' ya gotta sit up and take notice.

I would ask why, and then see if that condition was applicable to me too. In the industry I was in, the ‘experts ‘ insisted a hydraulic 6 side crimp on a big lug was correct and better. I let them do one, I did the opposite connection with a hammer and punch and solder. A week later I invited them back to witness their connection failing in rainbow colors of heat and corrosion, mine was perfect and cold.

just because something is better for someone, doesn’t mean it’s better for me Or my application.

 

[noenegdod]

I would ask why, and then see if that condition was applicable to me too. In the industry I was in, the ‘experts ‘ insisted a hydraulic 6 side crimp on a big lug was correct and better. I let them do one, I did the opposite connection with a hammer and punch and solder. A week later I invited them back to witness their connection failing in rainbow colors of heat and corrosion, mine was perfect and cold.

just because something is better for someone, doesn’t mean it’s better for me Or my application.

I would blame the pilot, not the plane. Personally Im not offended by either way. Crimping if you have the right tools and execute it well is a lot easier to do well.

 

[Browneye]

I made up welding wire with soldered terminals for a jeep winch, way back when. It worked well enough, but now in retrospect, had those lugs over-heated and the cable let go, it could have been a helluva mess.