SOK 48V battery package question

[KevinC_63559]

Hi guys...

My current little project is 12V, with (2) Fiunie 100amps (I suspect no-name, no-warranty that would be enforceable, but they were cheap on Amazon (under $200 delivered) and have bluetooth BMSes - so good for my starter project).

As I wait for my Victron based components to be delivered, I'm thinking about phase 2 of my project, which will be 48V base and probably 5-10 times as much of an investment. With that in mind, and due to the excellent support I'm getting at CurrentConnected, I'm considering their SOK 48V battery packages. One of the products features is the ability to get to and replace any component that fails with little more than a screwdriver and wrench. My question is: How much is that worth? What would likely fail? If the BMS fails, and replacement BMSes are available (likely, given the supplier rep), I could see huge value in that. If a battery cell fails (I'm presuming 16 cells inside the case), is it cool to just replace one? That seems to violate my understanding that all batteries in a series need to be from the same manufacturer and of similar age. So if one cells dies, since they are all in series, wouldn't I have to replace them all? Which is the most likely scenario?

Thanks in advance,

Kevin

 

[robby]

Having the ability to service batteries on site is a huge advantage. Just taking out and packing a 100lb battery is tough enough, add in the shipping fee to them and you will be crying!
Replacing one cell with a new cell is not a major problem. The cell they send you will be the same gangfeng cells. The new cell will just degrade faster until it matches the other 15 cells then it will level off and age in sync with them.
Some people like welded cells but personally I don’t see an advantage unless you’re putting them in a mobile system that is subjected to vibration.
The BMS is the most likely failure point and having the ability to easily get replacements is golden.

 

[Bluedog225]

It was worth a lot to me so I took the SOK rack route. A little annoying that they stopped selling the 4 battery rack in favor of the 5 battery rack. For my next 4 batteries, I’ll have to cut one down to make it fit the space.

Also, be careful when purchasing. There is a “pro” model and and a “dumb” model. And I’m told you cannot mix.

I’m not sure about the technical details on this but I think they cannot feed the same inverter? Or maybe communications don’t work. Anyway, a detail to work out before ordering.

Heavy. I’d recommend a helper for lifting them into place. I regret not having one.

When I purchased, it was in the face of some market uncertainty and a current connected pending price increase. That price increase didn’t pan out. Turns out prices have fallen and many expect them to go lower.

Current connected customer service has been pretty good so far.

 

[KevinC_63559]

Thanks folks. Had a humility moment... thinking how much lighter LiFePO4 batteries are - only about 25lbs per 12V100A. Didn't do the simple math: 4X25 = 100lbs each. At 65, that is an issue.

On the other hand, having the integrated communications (in the pro model) means I could presumably use the system's Cerbo GX to monitor everything in one spot vs. having to bluetooth into each 12V100 individually - and that is worth something significant.

 

[KevinC_63559]

Did more reading today... (what has become a daily event).

On the the big differences between the SOK Pro, the budget unit, and DIY racks of 12V100A in series battery is UL certification. May sound like a minor thing, especially if any part of your systems is NOT UL certified (and thus your exposed to insurance agencies rejecting claims), but...

UL1973 feels like a minimal rating, since its the General ESS safety certification
UL9540A feels like a really nice to have rating, since it certifies the units from having thermal runaway fire protection
UL9540 is more optional, being designed around smaller (<50KWh) non-residential applications.

The SOK Pro has the first two and is in pending status for the last. The SOK budget model does not, nor will it. Individual batteries may or may not...

Bottom line, if UL ratings are important to you - go Pro.

 

[G00SE]

I think it’s significant to be able to replace individual components.
There has been at least one instance in the past where someone was able to replace a SOK BMS. I think this would be feasible with most any common server rack battery.
But the bad cell proposition is a big deal. If you can replace one bad cell in an afternoon that’s a far quicker and cheaper turn around than freight.
I’d also rather have 15 matching cells and 1 slightly “newer” than a non functioning battery.
Each one of my cases has a spare cell for an oh crap moment.
I don’t think one could go wrong with their pro variant with the UL listings

 

[KevinC_63559]

I think it’s significant to be able to replace individual components.
There has been at least one instance in the past where someone was able to replace a SOK BMS. I think this would be feasible with most any common server rack battery.
But the bad cell proposition is a big deal. If you can replace one bad cell in an afternoon that’s a far quicker and cheaper turn around than freight.
I’d also rather have 15 matching cells and 1 slightly “newer” than a non functioning battery.
Each one of my cases has a spare cell for an oh crap moment.
I don’t think one could go wrong with their pro variant with the UL listings

Yeah, coming to that same conclusion. Cost more... worth it.

 

[Brucey]

I think Current Connected had mentioned that one of their clients got hit by lightning which took out a bunch of their batteries. Wasn't covered under warranty but the owner was able to replace just the BMSs and get back in operation. Having to ship seven or more big batteries back to a depot for replacement is way more of a hassle.