Which Crimp Connectors For Overkill BMS?

[Zwy]

I also have an Overkill Solar BMS, but I built my own harness with 20 AWG wire. That meant that the connectors we were both talking about worked fine.

I assume that you tried doubling the stripped wire? By that I mean stripping twice the length of insulation off, twisting the strands on the end so there is no fraying, and then bending the wire back on itself. That gives you a bigger wire to stick into the terminal for crimping. It's a pretty simple solution and I would assume you tried it, but I thought I would mention it. I've done this many times and it holds just fine.

After twisting and bending it over, I twist it again.

 

[HighTechLab]

Good to know Dexter. For the purposes of this thread, can you confirm one way or the other: Does JBD ship them with 22 AWG or 26 AWG balance harnesses?

EDIT: I see you added the answer after your original post. Thanks!

?

This is a gross oversimplification of industry practice. Crimping connectors is faster and cheaper than soldering. Crimping must be done carefully and good practices followed; soldering is no different. Crimping CAN be more reliable for fine wire in high-vibration environments like aircraft or automotive, but only IF the properly sized terminal is used. For stationary equipment with no vibration or mechanical stress, crimping THEN soldering with a minimal amount of solder (don't let it wick inside the wire insulation) can give the most reliable connection--especially if the crimp terminal is larger than the actual wire diameter.

The point is to exclude oxygen and moisture while allowing flexing and thermal expansion. Always allow some slack in the wire. Very tightly harnessed wiring with no slack is a bad idea generally, except in very specialized applications.

I don't totally agree that it's an oversimplification. Check out the video below where I hydraulically crimped some heavy-gauged battery cable and then cut through it with a carbide-tipped chopsaw. You can see that the copper has practically cold-welded together, creating a solid bond preventing oxygen penetration.

While I understand that using the wrong connectors for the balance leads actually surprisingly common, while still not very good, no matter which BMS (E.g. Daly, JBD, Etc.) is used, this is the #1 cause of customer issues after their systems have been up and running for a while.

I will reach out to my vendors in Asia to see if we can carry ring terminals designed for 22-26AWG wire with M6 & M8 terminals, so that we can get appropriate connections from BMSs to batteries. This could help some of these issues.

The other thing that I've started doing was having the bus bars I'm manufacturing for my batteries made with a hole in them to receive 8-32 threads, which can be tapped and use a far smaller ring terminal that is better suited for the tiny wire.

 

[Stepandwolf]

The other thing that I've started doing was having the bus bars I'm manufacturing for my batteries made with a hole in them to receive 8-32 threads, which can be tapped and use a far smaller ring terminal that is better suited for the tiny wire.

I am a bit confused about that method. If you have a bar between two batteries and attach the lead to the middle of the bar, wouldn't it be reading both cells or is that electrically the same as connecting to one or the other?

 

[Horsefly]

I am a bit confused about that method. If you have a bar between two batteries and attach the lead to the middle of the bar, wouldn't it be reading both cells or is that electrically the same as connecting to one or the other?

It's a bus bar. Anywhere on it - or on either end - is reading the same thing.

 

[Stepandwolf]

It's a bus bar. Anywhere on it - or on either end - is reading the same thing.

Assumed that was how it worked. Haven't considered drilling and tapping the bus bars vs. just putting the right terminal on the post.

 

[HighTechLab]

I am a bit confused about that method. If you have a bar between two batteries and attach the lead to the middle of the bar, wouldn't it be reading both cells or is that electrically the same as connecting to one or the other?

Picture worth 1000 words.

 

[Stepandwolf]

Picture worth 1000 words.

I knew what they looked like and have seen them set up that way in pictures.

 

[Brett V]

I've been an electronics technician since the Reagan administration and for small ring terminals going to the balance leads, I'll tell you a good soldered connection is better than any crimp. My experience however is most people don't know how to solder. A good flowed solder connection makes the ring terminal and the wire electrically one piece.

 

[Horsefly]

I've been an electronics technician since the Reagan administration and for small ring terminals going to the balance leads, I'll tell you a good soldered connection is better than any crimp. My experience however is most people don't know how to solder. A good flowed solder connection makes the ring terminal and the wire electrically one piece.

I was an engineer since the Reagan administration! I think a technician told me the same thing! Do I know you?!

 

[Stepandwolf]

What I haven't seen a thread on is how you bolt everything together. Assuming battery post on bottom, then buss bar or bars, the the BMS lead, then a serrated flange nut. You guys know better than me, but when researching products made to take vibration, I found the Nord-Locks and ordered a set.

Seems the prevailing trend I detect is get threaded holes, use a SS stud, Locktite red, BMS lead, then the flange nut?

Does everyone think the serrated flange nut is vibration-proof? Anyone using Nord-Lock in a mobile application?

 

[Brett V]

I was an engineer since the Reagan administration! I think a technician told me the same thing! Do I know you?!

If you tend to hang out in seedy low class joints, we may have met.
They made me an SE, (Systems Engineer). I didn't like it much and got back in the field. Now I mostly sit on my rear end in front of a computer and tell the kids in the field what they need to do.

Back on topic: For small wires, a good solder connection is golden. For large wires, a decent crimp is best. The amount of heat required to flow a good solder joint will damage the insulation and make the copper brittle.

 

[Horsefly]

If you tend to hang out in seedy low class joints, we may have met.
They made me an SE, (Systems Engineer). I didn't like it much and got back in the field. Now I mostly sit on my rear end in front of a computer and tell the kids in the field what they need to do.

You've heard of the Peter Principle, right? "If someone is good at their job, they will get promoted to a job they are not good at." I think I was a poster boy for the extreme version of this: "If someone is not good at their job, promote them so they won't do any more damage." So I stayed an EE at heart, but was in management most of my career.

 

[Brett V]

What I haven't seen a thread on is how you bolt everything together. Assuming battery post on bottom, then buss bar or bars, the the BMS lead, then a serrated flange nut. You guys know better than me, but when researching products made to take vibration, I found the Nord-Locks and ordered a set.

Seems the prevailing trend I detect is get threaded holes, use a SS stud, Locktite red, BMS lead, then the flange nut?

Does everyone think the serrated flange nut is vibration-proof? Anyone using Nord-Lock in a mobile application?

I Don't have a lot of hands on experience with the serrated flange nuts but they look good. A good old fashioned lock washer is still my first choice and for a more vibration resistant application where necessary, I'd pick a star washer.

 

[Brett V]

You've heard of the Peter Principle, right? "If someone is good at their job, they will get promoted to a job they are not good at." I think I was a poster boy for the extreme version of this: "If someone is not good at their job, promote them so they won't do any more damage." So I stayed an EE at heart, but was in management most of my career.

Moving in to management has been the hardest thing I've ever done...I suck at delegating.

 

[HRTKD]

What I haven't seen a thread on is how you bolt everything together. Assuming battery post on bottom, then buss bar or bars, the the BMS lead, then a serrated flange nut. You guys know better than me, but when researching products made to take vibration, I found the Nord-Locks and ordered a set.

Seems the prevailing trend I detect is get threaded holes, use a SS stud, Locktite red, BMS lead, then the flange nut?

Does everyone think the serrated flange nut is vibration-proof? Anyone using Nord-Lock in a mobile application?

A serrated flange nut on top of the bus bar is workable. A serrated flange nut on top of a balance lead, I'm not so sure about. What's to keep the ring terminal of the balance lead from turning against the bus bar?

I tried the management route. Didn't like it. Rumor has it that the HR department had to add a checkbox item to the exit interview form that said, "Jim's a Bastard!"

 

[Zwy]

What I haven't seen a thread on is how you bolt everything together. Assuming battery post on bottom, then buss bar or bars, the the BMS lead, then a serrated flange nut. You guys know better than me, but when researching products made to take vibration, I found the Nord-Locks and ordered a set.

Seems the prevailing trend I detect is get threaded holes, use a SS stud, Locktite red, BMS lead, then the flange nut?

Does everyone think the serrated flange nut is vibration-proof? Anyone using Nord-Lock in a mobile application?

I use the serrated nut and then add a nylon lock nut on top of that. I like the larger area of the serrated nut and wanted the lock nut for vibration. That was with threaded holes and I ordered studs long enough.

With the welded studs on my latest cell purchase, I'll have to look at the stud length but I think they will work. I do fab my own busbars out of thicker copper and nickel plate them.

 

[chrisski]

What type of nuts are you using?

The stud on the Eve 280s are M6, but not sure of the bolt material. I'm guessing aluminum, but an aluminum nut could be hard to find.

 

[John Frum]

What type of nuts are you using?

The stud on the Eve 280s are M8, but not sure of the bolt material. I'm guessing aluminum, but an aluminum nut could be hard to find.

Mine are m6.

 

[chrisski]

Mine are m6.

So will mine be and I edited the original post.

What material did you get for the nuts?

 

[John Frum]

So will mine be and I edited the original post.

What material did you get for the nuts?

stainless steel for flange nuts and set screws.