Leaking Electrolyte from Bigbattery Powerblock

[Hedges]

The circuit board isn't the only worry, there will also be large forces and vibration on the terminals. The cells themselves need to be fixed firmly in place, but still with flexibility for normal expansion under load. How on earth do you do that, with or without a circuit board?

I would want to hold the cells under compression and avoid mechanical stress on the terminals. Flexible busbars would seem the way to do that, although possibly holding cells under compression would mean the terminals don't move.

Alternative if compression isn't needed is to let them float and have rigid busbars. That would work with cells vertical and enough space between them for whatever pillowing is going to occur, but busbars couldn't attached during shipping.

I've seen some pictures of welded busbars that had bends, allowing flex as cells expand.

 

[Just John]

I would want to hold the cells under compression and avoid mechanical stress on the terminals. Flexible busbars would seem the way to do that, although possibly holding cells under compression would mean the terminals don't move.

Alternative if compression isn't needed is to let them float and have rigid busbars. That would work with cells vertical and enough space between them for whatever pillowing is going to occur, but busbars couldn't attached during shipping.

I've seen some pictures of welded busbars that had bends, allowing flex as cells expand.

I can't speak with authority for how these cells are actually used in China, but my understanding is the large ones are used in vehicles like a bus.
They are compressed in a fixture (limiting movement of terminals in 3 directions), and welded busbars are used. All that is really needed for a more demanding marine application would be to limit movement in the fourth direction (up) with a metal bar across the top between the cell terminals. I have seen this approach used on large batteries (like 48v rackmount). Of course then it would be difficult (not impossible) to use welded busbars. While braided busbars make sense, preventing the terminals from moving also makes sense, especially in a marine application that indeed will get a lot of up and down movement.

Now, for big battery, first they need to have more than one shelf (currently a stack of 4 cells presses on the bottom one). Due to variances in cells, they should probably put each cell on its own shelf, and perhaps use thin high density foam on the sides to make it stay in place, perhaps with a thin plastic membrane on the exterior to facilitate putting/shoving it in the "pocket". Then put a bar across the front of the stack, thus holding it in the last direction. Of course that still doesn't fix the problem if the cell is manufactured with a leaking vent cap. It also costs additional money to design and implement the changes to the sheet metal. To me, the better and cheaper fix is the bar across the top, and then just make the battery a horizontal one rather than vertical so the cells stand upright.

 

[sshibly]

Then you come up with who will pay?
The manufacturer of the faulty cells based in China?

good questions, do most businesses selling items buy some sorta insurance for liability???

 

[solarbot]

I would want to hold the cells under compression and avoid mechanical stress on the terminals. Flexible busbars would seem the way to do that, although possibly holding cells under compression would mean the terminals don't move.

Alternative if compression isn't needed is to let them float and have rigid busbars. That would work with cells vertical and enough space between them for whatever pillowing is going to occur, but busbars couldn't attached during shipping.

I've seen some pictures of welded busbars that had bends, allowing flex as cells expand.

Curved busbars are pretty common but it looks to me like they will still transfer plenty of load to the terminals. Some have used braided copper cable, but there are concerns about less reliable electrical contact and increased corrosion.

Firmly fixing the top and bottom of the cell while leaving the sides some expansion room would seem to be a promising approach, but harder to design and fabricate.

I would say there's still lots of room for progress in the art of prismatic cell mounting for mobile/marine, both on the DIY side and commercial. And I will equally say that it's clear BigBattery is far from an acceptable solution at the moment.

 

[Atomic Ed]

Curved busbars are pretty common but it looks to me like they will still transfer plenty of load to the terminals. Some have used braided copper cable, but there are concerns about less reliable electrical contact and increased corrosion.

Firmly fixing the top and bottom of the cell while leaving the sides some expansion room would seem to be a promising approach, but harder to design and fabricate.

I would say there's still lots of room for progress in the art of prismatic cell mounting for mobile/marine, both on the DIY side and commercial. And I will equally say that it's clear BigBattery is far from an acceptable solution at the moment.

Don't know if you noticed earlier in thread or not, but it turned out it was not even a Bigbattery product that leaked on that poor person but something from another vendor entirely.

Not trying to defend Bigbattery or anything but its not fair to blame them for this leaky competitors unit.

 

[solarbot]

Don't know if you noticed earlier in thread or not, but it turned out it was not even a Bigbattery product that leaked on that poor person but something from another vendor entirely.

I did notice it wasn't BigBattery, but it just bumped that whole sad story back to life. Plus there was a link in this thread to the "banned" post by MrGreen, which triggered me and reminded me among other things of how unsuitable those products are for marine use, in spite of claims.

 

[Atomic Ed]

I did notice it wasn't BigBattery, but it just bumped that whole sad story back to life. Plus there was a link in this thread to the "banned" post by MrGreen, which triggered me and reminded me among other things of how unsuitable those products are for marine use, in spite of claims.

Thanks. Understood, just didnt know if you were aware of it or not.

 

[sshibly]

Interesting article,

https://www.washingtonpost.com/business/2021/07/14/cpsc-sues-amazon/

 

[Atomic Ed]

Interesting article,

https://www.washingtonpost.com/business/2021/07/14/cpsc-sues-amazon/

Wow it said about 60% of products on scAmazon are from foreign sources.

 

[colemab]

Checking back in to say that the replacement renogy CC and Big Battery Hawk have both been 100% rock solid. I just placed an order for 2 more of the hawks (which would give me 6 total). I'll be sure to report in if there are any problems getting the 2 new ones added in.

I would eventually love to have 8 of them but I'm starting to wonder if anyone has hooked 8 (the max listed on specs sheet) of them up? Whats the largest non-diy off grid LifePo battery bank you all have seen?

 

[upnorthandpersonal]

Whats the largest non-diy off grid LifePo battery bank you all have seen?

Probably something like this:

 

[HRTKD]

Wow it said about 60% of products on scAmazon are from foreign sources.

I don't know if the article was update after you posted, but the article currently says this:

Nearly 60 percent of all physical goods sold on Amazon’s e-commerce marketplace come from third-party merchants.

 

[CarlN]

The biggest I've seen is eight Lithionics 315amp 12v drop-ins in a sailing catamaran.

 

[Atomic Ed]

I don't know if the article was update after you posted, but the article currently says this:

Not sure but when I read it, it said foreign sources.

 

[colemab]

So units 5 and 6 came in. And have orange handles? Also a new QR code sticker and a new info sticker on the side. I now have 26.1 kWh total.

 

[iSwannie]

That is good to hear. I currently have 4 of the 24v Hawks. Ian is saying I need a balancer but Victron said I didn’t. I am seeing some unbalancing at the top charges. Are you experiencing anything similar?

 

[colemab]

That is good to hear. I currently have 4 of the 24v Hawks. Ian is saying I need a balancer but Victron said I didn’t. I am seeing some unbalancing at the top charges. Are you experiencing anything similar?

Not sure what you mean. The BMSes manage the internal charging/ balancing in each unit. My units almost always read the same volts on the display if that is what you are asking.

 

[iSwannie]

Is your system 24v? Mine is 48v so I have (2) 24v banks in series with 2 sets in parallel. A total of (4) 24v 170ah Hawks.

 

[colemab]

Yes, I'm currently on 24v. So started with 2 in parallel then 4, now 6. The thought was that I'd either max out at 8 @ 24v or I could always reconfigure to be 2S4P @ 48v.

 

[iSwannie]

Yep, I did the same thing as you are thinking because I was so deep in the cost now I had to stick with the 24v Hawks. However, when you put these 24v 170ah Hawks in series it creates the issue I am having. I am not sure how to resolve this. It really seems like a balancer is needed between the 2 banks in series. Anyways I guess we can keep experimenting or getting recommendations from others that are using multiple 24v batteries to create a 48v system.