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Clean your terminals.

Bazzar

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Oct 6, 2020
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23
Location
North Carolina
I know its been said before but cleaning your terminals can make a world of difference.

I've been testing my 12v 4s 272ah Lishen pack and I had one cell that always was running 0.020-0.035v above or below @60A depending on if I'm discharging or charging. Now I had cleaned my terminals with a green scotch bright before I top balanced them a few weeks ago but had to wait about 2 weeks for my BMS due to backorder.

I got the BMS hooked everything up and started testing. Got the results above and also noticed that the terminal on that cell wat getting just slightly warmer then the rest of the connections 3-4f hotter after 30min at 90A. Finally took that bar off tonight re sanded everything and cleaned with cotton swab and alcohol reassembled and now I'm getting 0.001-2 difference @60A and 0.003-5 @ 125A much better.

I'm now waiting on my other order of 4 cells to double up my capacity and hope I get the same quality cells. Supposedly the supplier also upgraded the busbars between my orders so i had them add a set of the "upgraded" bars to put on the first pack since the forgot my double bus bars on the first order.

Anyways sorry for the long rant there but I hope this shows how important clean terminals can be.... even though I cleaned them 2 weeks before one must not have got as clean or got contaminated in 2 weeks and made me think I had a slight runner.
 
Bazaar,
I echo your sound advice. I’ve seen that cell voltage deviation can be reduced significantly by careful cleaning of the terminals, bus bars, and wire terminal lugs - using a Scotch-Bright pad. When I have a cell that looks to be out of balance, my first step now is to un-do the terminal connections, and carefully clean the mating surfaces with a Scotch-Bright bright pad, followed by a wipe with a clean rag.

But with studs inserted in the terminals, it is a bit of a chore to evenly scrub the entire terminal surface around the stud.

I’ve posted pictures below of my idiotically simple terminal cleaning tool. My cleaning method now is a small cut square of Scotch-Bright pad, with some holes pushed through it with a pencil, and a 5 or 6- inch length of broom handle, cut with a square end, and a 1/4-inch hole drilled in the square-cut end. Put the Scotch-Bright square over the terminal stud, through one of the holes, slip the wood “terminal-friction-cleaning-device“ over the stud. Rotate several times with a little down pressure. Easy. They have always come out clean, and low resistance, since I started using this high-tech cleaning tool.
 

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For aluminum connections some folks swear by NoAlox. Apply some to the aluminum, scuff while wet with 600 grit sandpaper, assemble.

I had a high resistance connection which resulted from a grain of sand stuck under the bus bar. Go figure!
 
For aluminum connections some folks swear by NoAlox. Apply some to the aluminum, scuff while wet with 600 grit sandpaper, assemble.

I had a high resistance connection which resulted from a grain of sand stuck under the bus bar. Go figure!
Are there any pros and cons of 600 grit sandpaper versus Scotchbrite.

Also, if using NoAlox is it important that it be applied immediately after cleaning (before significant new oxidation can occur)?

And lastly, it it’s important to coat the terminal with NoAlox immediately after cleaning, is there any rush to apply the lug and tighten that connection or can it be safely left that way for days/weeks?
 
For aluminum connections some folks swear by NoAlox. Apply some to the aluminum, scuff while wet with 600 grit sandpaper, assemble.

I had a high resistance connection which resulted from a grain of sand stuck under the bus bar. Go figure!
I’ve seen others recommending :

1. Scuff with sandpaper
2. Wipe with isopropyl
3. Apply oxguard/noalox

which is different from your method. I like that your method is simpler. i also like that oxguard is on during scuff so there is no chance of any oxidation immediately returning. Is it that important to do it this way? How quickly will aluminum start corroding? I thought galvanic corrosion wouldn’t take place unless there were different metal and electrons were flowing. Is this oxidation different than galvanic corrosion?
 
When soldering aluminum tubing etc I am I strutted to clean with a stainless steel brush, and clean with alcohol spray...
 
The only advantage to my suggestion over a standard buffing, is that doing so through a coating/gel inhibits the immediate formation of the oxide layer. Honestly I don't think it's worth it for most applications.
 
The only advantage to my suggestion over a standard buffing, is that doing so through a coating/gel inhibits the immediate formation of the oxide layer. Honestly I don't think it's worth it for most applications.
Oh, do you buff/sand wet with NoAlox.

Do you wipe off the wet dust/mud and then apply a fresh coat of NoAlox or just leave the residue full of sanded-off particles there?
 
Oh, do you buff/sand wet with NoAlox.
I am passing along the idea from others who use it. I can't speak to efficacy myself.

Yes it's wet sanding. If you use wet dry paper and a brief polish, there won't be a lot of debris. Same with a stainless brush. So wet assembly should be fine.

Crappy paper? Yeah, it will shed abrasive.
 
DeOxit and DeOxit Shield have been my go to stuff for bus bars and battery connections.

I've never had any corrosion problems since using it for many, many moons :)
 
For aluminum connections some folks swear by NoAlox. Apply some to the aluminum, scuff while wet with 600 grit sandpaper, assemble.

I had a high resistance connection which resulted from a grain of sand stuck under the bus bar. Go figure!
Is there any particular reason to use NoAlox while you are still building / screwing around? (top balance, capacity testing, BMS test & characterization, etc...).

My thought is to use NoAlox just before final assembly, but I want to make sure that not a bad idea.

I’ve not been particularly worried about cleaning and avoiding oxidation in the test and characterization phase (unless a poor / high resistance connection rears it’s ugly head).
 
Wow - so glad to see some taking cleaning your hardware seriously.

It's been hard for me to convince others to do likewise to not only clean, but the importance of using No-Alox or Penetrox. Not gobbed on afterwards, but a *thin* coat on all connecting hardware before assembly.

I like to point out that in many instances, one can have up to FOUR dis-similar metals in contact with each other:

1) Aluminum battery terminals.
2) Stainless nuts/bolts
3) Nickel plate or copper bussbars
4) Steel eye-rings for things like BMS connections

All clamped together. Looks good on day of install. Maybe even 4 years later, but if one measures internal resistance / impedance, this can be a major source of problems. Despite being tight, oxygen can creep in, so not only does the compound combat galvanic corrosion, it provides a layer of protection from oxidation.

Once I talk to them about Penetrox and the like being in your average hardware store, what is it used for mostly? The chance of old Vietnam era houses with aluminum wiring with crimps to copper outlets. Stories of people burning down houses because of this. And then they get it.

Just be sure not to buy a tube of NoAlox that has been sitting on the shelf for 15 years! :)

But I get it. One is so excited to get their DIY project up and running that this is often overlooked. Until the day they point say an an inexpensive IR-thermometer with a laser-pointer towards one of the terminals 4 years later!

Tip: don't use computer CPU thermal compound. Not the right stuff.
 
To be complete - DONT put NoAlox or Penetrox on the screw threads!

You'll strip or over-torque past specifications since it's so nicely lubed. Keep the threads bare.

But between washers and other flat surfaces? Yes.

Tip: Lock-washers and the like? Do NOT put them in-between the bus-bar and the actual battery terminal! Those need to be flush against each other, lock-washers and so forth belong on TOP!
 
Not a word about baking soda and water, vinegar or Coca-Cola?

How on earth do people get by without the products that people in this thread are talking about, which I imagine well over 99% of the world's population has never heard of?

:)
 
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