I WARNED YOU ALL! MB31/MB30 huge issue terminal snapping off

[PVGeezer]

Here is my solution for limiting the torque on the terminal weld while tightening the screws.

I bought a 36mm bicycle crowfoot on Amazon. It's thin enough to fit under the busbar. It's a little bit of a loose fit because the terminals are 35mm but it holds the terminal ok. Taped it up and the ratchet as well.

 

[Daddy Tanuki]

Here is my solution for limiting the torque on the terminal weld while tightening the screws.

I bought a 36mm bicycle crowfoot on Amazon. It's thin enough to fit under the busbar. It's a little bit of a loose fit because the terminals are 35mm but it holds the terminal ok. Taped it up and the ratchet as well.

ha ha ha PArk tools.. my chain splitter and my wrenches for taking off the bottom bracket are made by park... I probably have one of those in my MTB tool box somewhere..

 

[littleharbor2]

ha ha ha PArk tools.. my chain splitter and my wrenches for taking off the bottom bracket are made by park... I probably have one of those in my MTB tool box somewhere..

You da man.

 

[RCinFLA]

Another discovery of do not do. I used grub screws to avoid torquing terminal but found another way to break weld.

Make sure cells are not allowed to move side to side or try to tweak align of cells in a row after you have bolted down the four screws. Pushing cells a little to line up cells can torque the terminal enough to snap off weld which is only about 80 mils thick.

You are pretty much screwed unless you have a friend that happens to have a laser welder. Finding a welding shop with laser welder is tough. Finding a shop with laser welder that will do the job for less than 50-100% of original cost of cell is even tougher.

Quick spot tacking TIG welding, allowing cool down between tacks, still produces too much heating. Laser heats from surface staying in concentrated area while TIG heating is from deep material current bunching. Basically, red hot heat spreads out about 5x more for TIG.

If heating is enough for it to conduct down the terminal to foil layers (copper foil for neg, aluminum foil for pos) that are spot welded to bottom of terminal post, the heat will be conducted down the foil layers into the cell wrap where it melts the separator layers of perforated polymer plastic, shorting out cell. There is also the plastic grommet that the terminal post is mounted in to insulate it from metal case of cell that can melt and cause leakage of post seal.

You only have about 0.25" of aluminum thickness so not much to work with for drilling and tapping a hole. Break through to inside and cell is toast.

Clean terminal and bus bar surfaces with 91% isopropyl alcohol and dry before attaching bus bars. Only tighten to 3-3.5 ft-lbs of torque. You can check post-busbar-post resistance with YR1035 battery impedance meter.

I typically get 0.08 to 0.10 milliohm resistance readings post to adjacent cell post directly on cell posts with laminated flexible bus bars. Measured direct on cell post, not on top of bus bar or screw heads. That is lower resistance then I get on a single bolt cell terminal with nickel plated copper core 2x20x70 mm bus bars which I typically get 0.14 to 0.19 milliohms resistance cell post to cell post with 6 ft-lbs tightening torque.

 

[Daddy Tanuki]

Another discovery of do not do. I used grub screws to avoid torquing terminal but found another way to break weld.

Make sure cells are not allowed to move side to side or try to tweak align of cells in a row after you have bolted down the four screws. Pushing cells a little to line up cells can torque the terminal enough to snap off weld which is only about 80 mils thick.

this was one of my questions about the laser weld. welding for a living (in the past) i know a thing or two about this subject. and as I found out last week (eyesight is screwed) welding a thin metal even with top of the line, can't screw up gear is getting difficult (.5mm SS boiler tank) welding on these cells is no joke even with a laser welder. the margin for error is about zero. a little porosity ground cable not properly affixed, bad angle of the dangle and you got screw you city. and with 40+ years I was welding on SS and having issues due to my eyes... don't be fooled folks a solid grub screw into a solid terminal is likely to be more reliable

 

[ghostwriter66]

Picture was taken yesterday .... we have to unpack all the batteries at our storage facility about 50 miles away and then haul them like this to the offsite locations ... Otherwise the packaging simply takes up way toooo much room ... these things are packed like the crown jewels - but simply take up tooooo much room for transport

the 50 miles consists of about 27 miles of modified paved road (read: potholes that a VW can disappear into) and the rest are just plan ol' oil field roads .. some smooth -- some gravel ... some just god-forsaken ...

With OVER 10000 batteries being done in the last 3 months ... we have only had 5 failures so far ... and NOT a single POST has popped off ... one simply had NO charge at all from the factory ... and four of them crushed by a forklift I guess at the dock ...

We also simply use a battery powered impact wrench set on 8 newtons ...

If you look at my earlier pictures on this post you can see the cases we are putting them in ...

I swear though -- I would love to hook all the busbars up and power an entire drilling rig for an hour just for giggles ...

And as you can see - we do NOT baby our batteries ...

This was Trailer #1 of 3 trailers going out yesterday with the same load on each

 

[niktak11]

I don't think I could remove the terminals from mine if I tried

 

[ghostwriter66]

The thing that has been giving us some trouble though is our EEL vertical brackets ... Its a generic battery bracket holder that all the manufacturers use -- in this case EEL has put their name on this one ... but its no different then the 20 other ones we have from different manufacturers ...

BUT we have had several of them simply get soooooo HOT during the install that there is an obvious short in it somewhere ... they simply have sent us a handful of replacement boards when/if that occurs .. BUT man they get blazing HOT but NEVER actually stop working .. the BMS will shut itself off which is great -- but that does not stop the potential heat issue from continuing ..

and its always the LEFT (BLACK) side -- but that could be just happenstance ... we simply don't have time or the wherewithal to figure out the issue -- but going to say probably a short between battery #3 and the temperature sensor ...

 

[niktak11]

The thing that has been giving us some trouble though is our EEL vertical brackets ... Its a generic battery bracket holder that all the manufacturers use -- in this case EEL has put their name on this one ... but its no different then the 20 other ones we have from different manufacturers ...

BUT we have had several of them simply get soooooo HOT during the install that there is an obvious short in it somewhere ... they simply have sent us a handful of replacement boards when/if that occurs .. BUT man they get blazing HOT but NEVER actually stop working .. the BMS will shut itself off which is great -- but that does not stop the potential heat issue from continuing ..

and its always the LEFT (BLACK) side -- but that could be just happenstance ... we simply don't have time or the wherewithal to figure out the issue -- but going to say probably a short between battery #3 and the temperature sensor ...



View attachment 284513

What actually gets hot?

 

[ghostwriter66]

I don't think I could remove the terminals from mine if I tried

I remember when I first started out here -- i was basically on my on and was really the first and only solar engineer that they forced to come out here to pretend we cared about solar -- but I will ever so GENTLY tighten every nut and polish the busbars and do everything I could to make sure everything was perfect ... I am sure that if someone was watching me it looked like I was doing some sort of intricate process .....

NOW -- it looks and sounds like a NASCAR PIT CREW ... wipe it off -- slap it on -- tighten to the wrenchy thing clicks - 0.0004 seconds later -- DONE ... move to next one ...

LOL

 

[Daddy Tanuki]

Picture was taken yesterday .... we have to unpack all the batteries at our storage facility about 50 miles away and then haul them like this to the offsite locations ... Otherwise the packaging simply takes up way toooo much room ... these things are packed like the crown jewels - but simply take up tooooo much room for transport

the 50 miles consists of about 27 miles of modified paved road (read: potholes that a VW can disappear into) and the rest are just plan ol' oil field roads .. some smooth -- some gravel ... some just god-forsaken ...

With OVER 10000 batteries being done in the last 3 months ... we have only had 5 failures so far ... and NOT a single POST has popped off ... one simply had NO charge at all from the factory ... and four of them crushed by a forklift I guess at the dock ...

We also simply use a battery powered impact wrench set on 8 newtons ...

If you look at my earlier pictures on this post you can see the cases we are putting them in ...

I swear though -- I would love to hook all the busbars up and power an entire drilling rig for an hour just for giggles ...

And as you can see - we do NOT baby our batteries ...

This was Trailer #1 of 3 trailers going out yesterday with the same load on each

View attachment 284512

F me thats a lot of cells

 

[ghostwriter66]

What actually gets hot?

That entire GREEN board -- think of BLAZING hot -- then add 50C .... if you let it go on for 15 minutes or so the metal its on gets untouchable ... I have no idea what it would do if left completely unattended BUT I am assuming it would continue to heat everything around it to a point where fluids would be released ... BUT I am just guessing ... The good thing it happens right away during install ... we have never had one develop that issue AFTER leaving the depot ...

If we had more time we could rehook it one lead at a time and see where the issue is - but we simply switch and move on...

 

[niktak11]

That entire GREEN board -- think of BLAZING hot -- then add 50C .... if you let it go on for 15 minutes or so the metal its on gets untouchable ... I have no idea what it would do if left completely unattended BUT I am assuming it would continue to heat everything around it to a point where fluids would be released ... BUT I am just guessing ... The good thing it happens right away during install ... we have never had one develop that issue AFTER leaving the depot ...

If we had more time we could rehook it one lead at a time and see where the issue is - but we simply switch and move on...

That's very strange. I don't think my horizonal kits have that issue. Do any of the temp sensors pick it up?

 

[ghostwriter66]

F me thats a lot of cells

The sad part is that just to get to that point where they are on the trailer took more manhours then anyone expects ... first you have to open up over 250 boxes -- boxes that are extremally well packed and sealed ... then fight the foam thats holding onto the batteries like its their last friend ... then walk two at a time from the ground pallet to the trailer ... a 12 pound battery multiplied by almost 500 trips back and forth completely wears out our new little college grads that didn't read the fine print on page 27 of their contract that states -- in very small fonts -- "at times regardless of the position you were hired for, menial and physical labour may be required when circumstances arrive in order for mission success" (LOL) Man we use that catchphrase ALL the time out here ...

BUT then on the other end all of these same batteries are unloaded and then reloaded 16 at a time in vertical boxes ...

and although I LOVE vertical boxes -- its never the TOP_ battery that has an issue -- always the ones near the bottom -- thus you have to take all of them out to get to it ... aaaggghhh

 

[ghostwriter66]

That's very strange. I don't think my horizonal kits have that issue. Do any of the temp sensors pick it up?

YES -- right away -- and then it shuts off the BMS ... TEMP #2 sensor rapidly climbs followed by the remaining three ...

I think its just a bad batch of strips we got ...

 

[740GLE]

I just never saw the need for a PCB board vs long leads. But then again I don’t assemble batteries for hours on end.

 

[740GLE]

Picture was taken yesterday .... we have to unpack all the batteries at our storage facility about 50 miles away and then haul them like this to the offsite locations ... Otherwise the packaging simply takes up way toooo much room ... these things are packed like the crown jewels - but simply take up tooooo much room for transport

the 50 miles consists of about 27 miles of modified paved road (read: potholes that a VW can disappear into) and the rest are just plan ol' oil field roads .. some smooth -- some gravel ... some just god-forsaken ...

With OVER 10000 batteries being done in the last 3 months ... we have only had 5 failures so far ... and NOT a single POST has popped off ... one simply had NO charge at all from the factory ... and four of them crushed by a forklift I guess at the dock ...

We also simply use a battery powered impact wrench set on 8 newtons ...

If you look at my earlier pictures on this post you can see the cases we are putting them in ...

I swear though -- I would love to hook all the busbars up and power an entire drilling rig for an hour just for giggles ...

And as you can see - we do NOT baby our batteries ...

This was Trailer #1 of 3 trailers going out yesterday with the same load on each

View attachment 284512

So that’s 50 miles of that case wrapping getting abraded? Not to mention dust covered.

Def a great stress test, fingers crossed.

 

[HRTKD]

I just never saw the need for a PCB board vs long leads. But then again I don’t assemble batteries for hours on end.

The PCB sure is a nice clean install. Wrangling eight balance leads plus two temperature sensors is a step I wouldn't mind skipping. But if the PCB isn't reliable I'm OK with being a cable cowboy.

The failure rate is low, but it's worrisome to have that problem on such a simple part.

 

[Skypower]

That entire GREEN board -- think of BLAZING hot -- then add 50C .... if you let it go on for 15 minutes or so the metal its on gets untouchable ... I have no idea what it would do if left completely unattended BUT I am assuming it would continue to heat everything around it to a point where fluids would be released ... BUT I am just guessing ... The good thing it happens right away during install ... we have never had one develop that issue AFTER leaving the depot ...

If we had more time we could rehook it one lead at a time and see where the issue is - but we simply switch and move on...

There shouldn’t be anything but balance current on those boards and that should not be happening at assembly. This sets off a lot of alarm bells in my mind

 

[rhino]

The thing that has been giving us some trouble though is our EEL vertical brackets ... Its a generic battery bracket holder that all the manufacturers use -- in this case EEL has put their name on this one ... but its no different then the 20 other ones we have from different manufacturers ...

BUT we have had several of them simply get soooooo HOT during the install that there is an obvious short in it somewhere ... they simply have sent us a handful of replacement boards when/if that occurs .. BUT man they get blazing HOT but NEVER actually stop working .. the BMS will shut itself off which is great -- but that does not stop the potential heat issue from continuing ..

and its always the LEFT (BLACK) side -- but that could be just happenstance ... we simply don't have time or the wherewithal to figure out the issue -- but going to say probably a short between battery #3 and the temperature sensor ...



View attachment 284513

I wonder if they are all going to eventually be using the updated PCB that Yixiang started using shown in this video:

 

[Dagoth Ur Does Solar]

So did I get it right that the gist of this was that OP had either a bad batch/bad QC and that this isn't an issue for most cells?

 

[ghostwriter66]

So that’s 50 miles of that case wrapping getting abraded? Not to mention dust covered.

Def a great stress test, fingers crossed.

YEP. There is slight wiggle room between each battery - very slight - but so far we have not had any rub together to a point where the case is showing ... and I guess if that does happen we will just wrap thick electrical tape around it ...

BUT YES _ the first time these arrived I thought for sure that 50% would be shot or dead ... they will use a high pressure spray to clean the tops off and then high pressure air to dry them ...

Again - when you see this the first time you want to yell - WTH !!! But 10,000 batteries later - no issues ... They do wipe down the sides during installs ...

 

[ghostwriter66]

I just never saw the need for a PCB board vs long leads. But then again I don’t assemble batteries for hours on end.

The issue is that THIS way it so much faster PLUS you don't have a rats-nest of wires you are trying to figure out what goes where ...

 

[ghostwriter66]

There shouldn’t be anything but balance current on those boards and that should not be happening at assembly. This sets off a lot of alarm bells in my mind

We are thinking that there is some sort of bleed over / touching going on on that board from basically sloppy PCB building -- of course the factory told us that when they do a run - they do like 15000 a day .... going to say that at that speed quality control is you and me ...

 

[ghostwriter66]

So did I get it right that the gist of this was that OP had either a bad batch/bad QC and that this isn't an issue for most cells?

OR he just cranked it down way past the 08 Newtons recommended ...