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diy solar

I have the poor connection blues - help me

J

JaVid

New Member
Joined
Aug 5, 2020
Messages
154
I have (2) 280Ah 24V diy battery packs that I have had up and running for about a year now. I am off grid and these batteries have literally changed my life in so many ways, but I have had connection/corrosion issues that seem to crop up more and more and I am looking for a solution.

I am using the tinned busbars that came from Basen with my cells and when I initially put them together, I gave each connection (both the terminal and the busbar) a light sanding with 3M P320 sandpaper, wiped them down with isopropyl alcohol, and then a light coating of Ox-guard and tightened them up snug. This seems to work out fine for the short terms, but every month or two my BMS shows something strange on a cell and I need to take things apart near that cell and re-do them.

Do other folks who made a DIY battery have these issues? If you have had your batteries put together for longer than 6 months and aren't having any of these issues, can you tell me what you did to connect the batteries? Anybody see any issues with how I did the connections? Was it a mistake to lightly sand the tinned busbars? I am willing to invest in a new or better solution so any suggestions welcome. Thanks!
 
What kind of connectors do your cells have? Welded studs? Female threads? What size?
 
My 280Ah is holding up fine bouncing around in the trailer. Seems like you have the electrical side covered. Do you have the cells in compression to keep any physical stress off the terminal connections?
 
TomC4306 said:
Buy a torque wrench.
Click to expand...
When I bought these cells everyone warned how weak the threads were. So I put studs in them and used loctite to hold the studs. I still use allen wrench to back the stud when I at tightening. Not sure how I would use torque wrench in this set up. The batteries are stationary. You think the lack of torque is allowing oxidation?
 
TacomaJoe said:
My 280Ah is holding up fine bouncing around in the trailer. Seems like you have the electrical side covered. Do you have the cells in compression to keep any physical stress off the terminal connections?
Click to expand...
My Batteries are stationary and they are not in compression. They are spaced apart so no physical stress on busbars.
 
Can you share a picture of your connection? If the loctite is in the current path you will have problems (IIRC).
 
Shimmy said:
Can you share a picture of your connection? If the loctite is in the current path you will have problems (IIRC).
Click to expand...
I will get a picture tomorrow of my set up. The loctite is not in the current path - I was careful with it when installing the stud and any loctite that got on the terminal was sanded off - very small amount got on. The current path is the busbar/terminal connection.
 
JaVid said:
Female threads that I have put studs into with Red Loctite. Not sure what size.
Click to expand...

Red is complete and total overkill and will ensure the destruction of your terminals if you ever need to remove them. Use blue or purple.

JaVid said:
When I bought these cells everyone warned how weak the threads were. So I put studs in them and used loctite to hold the studs. I still use allen wrench to back the stud when I at tightening. Not sure how I would use torque wrench in this set up.
Click to expand...

Deep well socket.

1658277601973.png
This is what I used for my 588 5mm thd, 8mm hex nuts

JaVid said:
The batteries are stationary. You think the lack of torque is allowing oxidation?
Click to expand...

A lack of torque can cause all kinds of problems..
 
sunshine_eggo said:
No idea. Lots of accounts of it's magical properties. I just used a bunch to attach 60 feet of Aluminum bus bars to nickel plated copper terminals.
Click to expand...
I will pick some up. Thanks for recomendation. 60 feet of aluminum bus bars? That must be a big system! Where did you get your bus bars from?
 
sunshine_eggo said:
Red is complete and total overkill and will ensure the destruction of your terminals if you ever need to remove them. Use blue or purple.



Deep well socket.

View attachment 103291
This is what I used for my 588 5mm thd, 8mm hex nuts



A lack of torque can cause all kinds of problems..
Click to expand...
Well, I am not sure why I would want to remove the studs, but you are right - the red is supposed to be permanent (at least I hope - there might have been cutting oil in the threads which would change that). Its hard to bring those days back, but everyone was getting cells with terrible threads (not vertical and of varying depths and quality) and they were stripping out constantly. Lots of folks were using JB Weld rather than loctite red.

The studs I installed have a hex on top and I use those to keep the studs from moving and getting dislodged. Then I use open ended wrench for tightening the nut. That is why hard to use torque wrench...
 
TomC4306 said:
I was impressed with this one when I received it.

I didn't need these but they are available. Called crowfoot wrench.

Proto - 1/4" Drive Crowfoot Wrench 1/4" - Open End (J4708CF) - - Amazon.com

Proto - 1/4" Drive Crowfoot Wrench 1/4" - Open End (J4708CF) - - Amazon.com
www.amazon.com
Click to expand...
Thanks for the links - that crowfoot wrench is just what I need to also keep stud in place...
 
Just be aware that using a crowsfoot with a torque wrench can change the actual torque applied to the fastener. This is because the length of the lever can be longer or shorter depending on the angle of the crowsfoot in relation to the arm of the wrench. For accuracy, you should keep the crowsfoot at 90 degrees to the torque wrench.

www.tekton.com

How to Accurately Use a Torque Wrench with a Crowfoot Wrench | TEKTON Hand Tools

Learn how to accurately use a torque wrench with a crowfoot wrench to measure torque. Use the included Torque Conversion Calculator.
www.tekton.com www.tekton.com
 
JaVid said:
I have (2) 280Ah 24V diy battery packs that I have had up and running for about a year now. I am off grid and these batteries have literally changed my life in so many ways, but I have had connection/corrosion issues that seem to crop up more and more and I am looking for a solution.

I am using the tinned busbars that came from Basen with my cells and when I initially put them together, I gave each connection (both the terminal and the busbar) a light sanding with 3M P320 sandpaper, wiped them down with isopropyl alcohol, and then a light coating of Ox-guard and tightened them up snug. This seems to work out fine for the short terms, but every month or two my BMS shows something strange on a cell and I need to take things apart near that cell and re-do them.
Click to expand...

What is this "something strange"? also is it reoccurring on the same cell?

JaVid said:
Do other folks who made a DIY battery have these issues? If you have had your batteries put together for longer than 6 months and aren't having any of these issues, can you tell me what you did to connect the batteries? Anybody see any issues with how I did the connections? Was it a mistake to lightly sand the tinned busbars? I am willing to invest in a new or better solution so any suggestions welcome. Thanks!
Click to expand...

I have not had these issues in such a short time span.

320 grit probably a bit much. I would say light sanding with 1000+ would be ok.

What is your environment like? Very humid? Salt?
 
I used mg chem 847 and it's doing great on one set, and it is marginal on another. I'm looking at flexible bus bars to minimize movement. I'm also checking connections regularly now. I guess it's better than watering?

Btw, even the red loctite will most likely free easily on aluminum. You have to surface prep and use the aluminum mix.

Also, if you hand torqued, you could have over torqued. I used a torque wrench, and I certainly would have over torqued without it.

I don't think marginal connections are really noticable at low amps. Around 100amps it really shows though.
 
BradCagle said:
What is this "something strange"? also is it reoccurring on the same cell?



I have not had these issues in such a short time span.

320 grit probably a bit much. I would say light sanding with 1000+ would be ok.

What is your environment like? Very humid? Salt?
Click to expand...
"something strange" is when the BMS shows a cell suddenly out of whack with the rest of the cells. This is usually only noticeable when charging and when it is in discharge mode everything looks like it should. I believe this happens because of greater resistance. It has happened in a variety of cells and happened first in a place where I needed to make custom busbars with copper (not tinned) - last few times it has happened where my regular tinned busbars are. Its only happened 5-6 times total and isn't a huge deal, but this thread trying to figure out how to prevent for next bunch of years when I am not so gung ho on babysitting the battery...

Good hint on 1000 grit sandpaper. Environment is upper midwest in a non-heated shed (battery box has heaters for cold months)
 
bgflyguy said:
I used mg chem 847 and it's doing great on one set, and it is marginal on another. I'm looking at flexible bus bars to minimize movement. I'm also checking connections regularly now. I guess it's better than watering?

Btw, even the red loctite will most likely free easily on aluminum. You have to surface prep and use the aluminum mix.

Also, if you hand torqued, you could have over torqued. I used a torque wrench, and I certainly would have over torqued without it.

I don't think marginal connections are really noticable at low amps. Around 100amps it really shows though.
Click to expand...
You are right that it is better than watering! These batts are a real life changer for off-grid living. I used to just have a chest freezer to fridge conversion and some lights. Now I have regular fridge, microwave, mini split, chest freezer, and induction cooktop. I have to pay attention to batteries when using mini split overnight, but that is only compromise currently and I hope to automate.

I am aware of the red loctite maybe not forever - that is why I use the hex on the stud head when tighten and loosening. None have broken free yet (out of 16), but I know it will likely happen.

Is overtorquing bus bars an issue with connection and corrosion?

I agree about the low amps not showing up as well. I plan to try to get things "right" and then if I am still having these issues, I plan to buy a flir camera and just look everything over once a month with a decent load and hopefully be able to "see" exactly what needs addressing instead of sorta guessing
 
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