flange nuts require a flat washer?

[John Frum]

I will need to use grub screws with my big blue prismatic cells.
I plan to use flange nuts with the grub screws.
I understand the flange nut will make a lock washer unnecessary but do I need a flat washer?

 

[RachelClarson]

In effect a washer will protect a surface more than a flanged nut.

 

[HRTKD]

The flat washer would negate the effectiveness of the flange washer if it looks like this:

 

[ArthurEld]

I think the flanged nut would still lock against the washer. If you don't use a washer the serrated surface of the nut will scratch your buss bars.
I don't use a washer and my busbars are all scratched up.

 

[HRTKD]

If you don't like scratches then don't use a flange nut with a serrated surface. The flat washer will allow the flange nut to turn. A flange nut against a bus bar is far less likely to turn because the bus bar doesn't move.

 

[John Frum]

I guess I don't mind scratches.
If all goes to plan I'm only doing the joinery once.
Jinx!

 

[ArthurEld]

It scratched through the coating on mine. I seem to remember you having some nicer busbars. That is why I mentioned it.

 

[Gazoo]

If you don't like scratches then don't use a flange nut with a serrated surface. The flat washer will allow the flange nut to turn. A flange nut against a bus bar is far less likely to turn because the bus bar doesn't move.

This is also a good reason to not mount the BMS balancing ring terminals below the serrated nut.

 

[HRTKD]

This is also a good reason to not mount the BMS balancing ring terminals below the serrated nut.

Good point. I didn't think of that. One more reason to drill a hole in my bus bar and tap it for threads.

 

[John Frum]

It scratched through the coating on mine. I seem to remember you having some nicer busbars. That is why I mentioned it.

I believe you are referring to my system busbars.
I was planning to use grub screws and with 1oz busbars to connect my 280ah cells.
for the busbar connects from the bottom up would be...

terminal​

1oz busbar​

(ring terminal) for the balance/sense points​

flat washer​

lock washer​

6mm bolt​

For the most positive and most negative

terminal​

mechanical lug​

ring terminal​

flange nut​

​

 

[snoobler]

I'm going to muddy the water.

The only thing that matters is the contact surface between the top of the battery terminal and the bottom of the bus bar. The clamped contact area is notably larger than the bus bar cross section.

It essentially doesn't matter what you use or how you do it provided the bus bar is adequately clamped to the terminal.

Sense leads matter even less because they carry negligible current.

I've disassembled many hybrid vehicle packs. None use washers or serrated flange nuts, and they pass 100-150A of current and absurd amounts of POWA! Stack: Terminal face, bus bar, smooth flange nut. For the connection that has sense leads: terminal face, bus bar, sense ring terminal, flange nut.

Properly torqued nuts will not come loose, washer or not.

Personally, I prefer smooth flange nuts for more accurate torque values.

 

[John Frum]

I'm going to muddy the water.

I would say you un-muddied the water.

 

[ArthurEld]

I believe you are referring to my system busbars.
I was planning to use grub screws and with 1oz busbars to connect my 280ah cells.
for the busbar connects from the bottom up would be...

terminal​

1oz busbar​

(ring terminal) for the balance/sense points​

flat washer​

lock washer​

6mm bolt​

For the most positive and most negative

terminal​

mechanical lug​

ring terminal​

flange nut​

​

Sounds good. I personally don't like the bolts but I'm sure you can make it work.
Since you have ring terminals under the nuts they won't scratch anything.

 

[John Frum]

Should have mentioned.
Its a stationary setup of fairly constant 25C and 60-70% humidity.

 

[snoobler]

I would say you un-muddied the water.

I thought it arrogant to add... "...with clarity... "

 

[ArthurEld]

Yea I should have just said those serrated flange nuts suck.

 

[John Frum]

I've changed my mind
going with
for the busbar connects from the bottom up would be...

terminal

1oz busbar(came with battery)​

(ring terminal) for the balance/sense points​

flat washer(came with battery)​

lock washer(came with battery)​

6mm bolt(came with battery)​

For the most positive and most negative

terminal with 6mm stainless steal grub screw​

mechanical lug​

ring terminal​

flat washer​

lock washer​

nut​

 

[Chris61]

I will need to use grub screws with my big blue prismatic cells.
I plan to use flange nuts with the grub screws.
I understand the flange nut will make a lock washer unnecessary but do I need a flat washer?

I used a flat washer and flange nuts, probably not ideal if the nut is going to work loose, however I believe ths won't happen on the battery. The use of studs over bolts is the only way to go if you won't to stop the chance of stripping out a thread in battery terminal. I also used a hi tensile grub screw instead of stainless steel

 

[Campin]

...I've disassembled many hybrid vehicle packs. None use washers or serrated flange nuts, and they pass 100-150A of current and absurd amounts of POWA! Stack: Terminal face, bus bar, smooth flange nut. For the connection that has sense leads: terminal face, bus bar, sense ring terminal, flange nut.

Properly torqued nuts will not come loose, washer or not.

Personally, I prefer smooth flange nuts for more accurate torque values.

Prior to ordering parts I’ll forum-search and read opinions. This makes sense to me and ArthurEld‘s comment about serrated scratching drove home the point. ...ordered smooth ss A2 flange nuts. Thank you

 

[ArthurEld]

I switched to regular nuts and flat washers.
It is kind of a pain using two items instead of one but it is what I like.
I don't feel that I need to use lock washers.

The serrated flange nuts would be good for people who just put the battery together and use it. Or mobile applications.
I took mine apart multiple times and the busbars got gouged up to the point that they needed to be filed flat.
And the plating got messed up.