Torque specs for the EVE 280Ah cells with welded studs

harpo

Good at many things, master of none
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Oct 1, 2019
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PA, FL
I got my EVE cells a couple weeks ago and now ready to assemble my battery in a permanent configuration so I want to use the proper torque on all connections.

I did not get a spec sheet with my cells like many of you have mentioned I would. Just the cells. No paperwork of any kind in the boxes. Bought from AMY.

I researched this forum on torque specs for the welded studs but most of the posts about this were older and primarily addressed the cells with bolts provided. So, I'd like to know what I should torque these down to.

Additionally, I have bolt connections on the Victron Smart Shunt and the Overkill BMS. Torque specs on those would be helpful as well. The bolts on the Smart Shunt are massive 3/8" thread (or metric equivalent) and have no clue what the torque on those should be or how much torque to put on them and not break anything.
The BMS has M6 bolts to attach the cables to and any suggestions on those would also be really appreciated.

Not sure why these values are not front and center on any paperwork/manual so as to limit the danger of over tightening and potentially either stripping the threads or, for example on the BMS, stressing the connections of the bolt plates to the board.

Thanks to all. You've been a great help in getting me this far and I can finally see the finishline.
 

rickst29

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Reno, NV
It depends, there are several types of EVE welded studs. If yours are like mine, https://diysolarforum.com/attachments/eve-230ah-terminals-jpg.86695/ then they allow up to 10nM = 88 inch-lbs, slightly more than 3x greater than the 25 inch-pound maximum spec for previous screw-into-the-body posts. But those also varied according to battery size and thread diameter. In building some smaller 'screw-into-the-body' battery packs from non-Eve cells in the past, I never exceeded 15 inch-pounds on those M6 post screws, because I feared stripping the threaded aluminum holes if I went higher.

These newer posts are made of a stronger alloy, and supposedly won't strip so easily. "They" say that the very high contact pressure makes up for the extremely small area of contact with the top of the cylindrical post. But many forum members have their doubts, adding washers and other conductive filler around the skinny posts, to improve the total surface area. There are a couple of new and active Threads about that. I'm going to try high torque without extra washers surrounding the post first, crank up the load battery load, and carefully feel if the terminals get warm to the touch - if they do, then I'll take it apart and add some washers.
 

Dynoman

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Joined
Dec 17, 2020
Messages
133
Location
Michigan
I got my EVE cells a couple weeks ago and now ready to assemble my battery in a permanent configuration so I want to use the proper torque on all connections.

I did not get a spec sheet with my cells like many of you have mentioned I would. Just the cells. No paperwork of any kind in the boxes. Bought from AMY.

I researched this forum on torque specs for the welded studs but most of the posts about this were older and primarily addressed the cells with bolts provided. So, I'd like to know what I should torque these down to.

Additionally, I have bolt connections on the Victron Smart Shunt and the Overkill BMS. Torque specs on those would be helpful as well. The bolts on the Smart Shunt are massive 3/8" thread (or metric equivalent) and have no clue what the torque on those should be or how much torque to put on them and not break anything.
The BMS has M6 bolts to attach the cables to and any suggestions on those would also be really appreciated.

Not sure why these values are not front and center on any paperwork/manual so as to limit the danger of over tightening and potentially either stripping the threads or, for example on the BMS, stressing the connections of the bolt plates to the board.

Thanks to all. You've been a great help in getting me this far and I can finally see the finishline.

I had the same question when I started to assemble my CATL 271ah cells. A search found messages that said it was OK to torque the nuts to 10 nm or 88.5 in lbs. for cells with laser welded steel studs. Some did so successfully with no problems. Others pointed out that Eve has a spec of only 8 nm or 70.8 in lbs. torque for the terminal pads.

I decided to play it safe and torqued the nuts to 70 in lbs. on the cells with a torque wrench. The connections are nice and tight and there are no bad connections. All the connections stay cool when measured by touch and a thermal gun. The Victron shunt and OverKill Solar BMS nuts are also torqued to 70 in lbs.

I also filed off any burs on the bus bars & cleaned all connections with 99.9% isopropyl alcohol. It was amazing how much crud was on the battery terminal, stud and wire lugs.

It is my understanding that some of the laser welded studs are also aluminum and not steel. If that is the case I would think the torque would be lower, but I don't know.

I have attached a picture of my stud configuration.
 

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harpo

Good at many things, master of none
Joined
Oct 1, 2019
Messages
89
Location
PA, FL
Thanks for the replies!

Dynoman, that is the same setup I have-----M6 welded studs. 70 in/lbs sounds about right.

Now, about the other torque specs; Overkill has M6 bolts on their BMS and their manual for this BMS says a whopping 20 ft/lbs (not a misprint). I have contacted them and waiting to hear back. I can't believe that figure. That is like 240 in/lbs!!

The Victron Smart Shunt has huge M10 bolts for making the connections. I have to believe they need to be tightened down pretty good but don't have a figure on that. I have "heard" 150-190 in/lbs but nothing from Victron so kind of flying blind.
 

Dynoman

Solar Enthusiast
Joined
Dec 17, 2020
Messages
133
Location
Michigan
Thanks for the replies!

Dynoman, that is the same setup I have-----M6 welded studs. 70 in/lbs sounds about right.

Now, about the other torque specs; Overkill has M6 bolts on their BMS and their manual for this BMS says a whopping 20 ft/lbs (not a misprint). I have contacted them and waiting to hear back. I can't believe that figure. That is like 240 in/lbs!!

The Victron Smart Shunt has huge M10 bolts for making the connections. I have to believe they need to be tightened down pretty good but don't have a figure on that. I have "heard" 150-190 in/lbs but nothing from Victron so kind of flying blind.

It would seem the torque could be higher for the Victron Shunt, possibly 100 in lbs. or more, but 70 in-lbs. seemed sufficient with a good connection and no heat. It appears to be made of brass so I wanted to be sure not to strip the threads.

I did go to 120 In-lbs. on my Blue Seas bus bars since they have a spec of 132 in-lbs., but they have 5/16 in SS studs so it should take more. 120 in-lbs. was an extremely tight connection... couldn't see the need to go tighter.

70 in-lbs. seemed sufficient on the BMS. The bolt holes on mine are only connected (soldered) in the 4 corners and didn't look like it could take much torque to me. Again the connection is good with no heat.

I bought a torque wrench after pulling a stud out of an inverter by over-torqueing. I now tend to be on the side of caution when torqueing. Definitely need enough for a good connection, but not more than that in my opinion.

If you find out different from Overkill Solar or Victron Shunt please post it here.
 
Last edited:

harpo

Good at many things, master of none
Joined
Oct 1, 2019
Messages
89
Location
PA, FL
It depends, there are several types of EVE welded studs. If yours are like mine, https://diysolarforum.com/attachments/eve-230ah-terminals-jpg.86695/ then they allow up to 10nM = 88 inch-lbs, slightly more than 3x greater than the 25 inch-pound maximum spec for previous screw-into-the-body posts. But those also varied according to battery size and thread diameter. In building some smaller 'screw-into-the-body' battery packs from non-Eve cells in the past, I never exceeded 15 inch-pounds on those M6 post screws, because I feared stripping the threaded aluminum holes if I went higher.

These newer posts are made of a stronger alloy, and supposedly won't strip so easily. "They" say that the very high contact pressure makes up for the extremely small area of contact with the top of the cylindrical post. But many forum members have their doubts, adding washers and other conductive filler around the skinny posts, to improve the total surface area. There are a couple of new and active Threads about that. I'm going to try high torque without extra washers surrounding the post first, crank up the load battery load, and carefully feel if the terminals get warm to the touch - if they do, then I'll take it apart and add some washers.
Rickst29; let me know how your little experiment turns out. Interested in that issue as well.
 

rickst29

Solar Addict
Joined
Mar 27, 2021
Messages
640
Location
Reno, NV
Rickst29; let me know how your little experiment turns out. Interested in that issue as well.
I have the 4S battery cells undergoing a balancing charge right now, and I have some good busbars (to avoid creating heat and resistance within bus bars themselves). What I won't have, until about March 30, is a high-powered 120v Inverter, so that I can create sufficient load for testing the pack at high current. (When I attach a toaster and a coffee maker to that Inverter, the battery should definitely feel the current).
 

rickst29

Solar Addict
Joined
Mar 27, 2021
Messages
640
Location
Reno, NV
Rickst29; let me know how your little experiment turns out. Interested in that issue as well.
The experiment is 'complete', although I did not have a good set of appliances to reach a load near 200A. Running a couple of AC appliances through my newly-arrived 'el cheapo'Inverter, at barely 70% efficiency per the Daly BMS current report, I pushed the battery terminals (and internal bus bars) to about 150A continuous. The Toaster + Coffee Maker together were too much, exceeding the Daly output current limit.

At 150A continuous, all of my terminals stayed cold (room temperature) for more than 4 minutes, and the cells did not warm up either. I was, however, going only by "feel", my very accurate thermocouple-based temp probe being lost (somewhere in the basement).

My busbars are really great. I tightened the threaded posts into the eve terminal "cylinder" fairly tight to begin with (about 50 inch-pounds), and then pressed everything into those bolts by tightening the washered nuts to about 70 inch-pounds (12% less than their rated maximum torque values).

My Daly "200A" BMS came was built with somewhat compromised "B -" and "P -" connectors: The terminal lugs had holes at least 8mm in size, (maybe even bigger than that), and the wires were labeled "AWG 2". The label is a bit misleading (the actual wire size is closer to AWG-1). The connectors are also longer than my battery pack requires. I cut off both of the terminal lugs and replaced them with my own (1-AWG wire size with 1/4" holes, barely larger than the 6mm battery studs). For the case of "P -", I also cut off a lot of the factory-supplied BMS wire length, so that current flow through these "1-AWG" wire segments for as little length as possible. My main power wires (12v and grounding) to this battery are AWG 2/0.
 
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