Help with 128 batteries each one is 280ah, and want to configure for 48v system.

[Shawn Hayes]

Just wanted to give an update and reach out with a question for anyone with Batrium BMS experience. I have ordered 64 LiFePo4 batteries (4p16s) and I am expecting them in the next couple of weeks. I ordered the Batrium Watchmon Core and 16 Blockmons M8’s and the Batrium arrived today.
I already know that based on my desired layout and battery spacing that I will have to lengthen some of the Blockmons M8 cabling. Just curious for those of you with Batrium experience, if you had to lengthen you’re Blockmon cables? If so, what your suggestions or recommendations would be based on your experience?

 

[kromc5]

I did not have to lengthen mine luckily but I have seen batrium discuss doing so with no issues in videos when I was researching.
What type of layout are you using?


I will have to lengthen one when I get my spare batteries, I will be combining two 4p16s on one barium.

 

[Shawn Hayes]

What type of layout are you using?

I’m doing a 4p16s layout. However I’m using a custom rack inside a metal cabinet, see below:
Layout for batteries:
Battery rack & cabinet:


So I will need to lengthen the first & last Blockmons cables to get to the ISOmon. Maybe even each one going from shelf to shelf between each row of 16 batteries.
4 batteries high and 4 wide per shelf, 16 per row. 64 total making 4p16s.

 

[kromc5]

I’m doing a 4p16s layout. However I’m using a custom rack inside a metal cabinet, see below:
Layout for batteries:
Battery rack & cabinet:


So I will need to lengthen the first & last Blockmons cables to get to the ISOmon. Maybe even each one going from shelf to shelf between each row of 16 batteries.
4 batteries high and 4 wide per shelf, 16 per row. 64 total making 4p16s.

That is an interesting layout, what will you use to connect the batteries dual 4/0 or 2/0?

 

[Shawn Hayes]

That is an interesting layout, what will you use to connect the batteries dual 4/0 or 2/0?

Actually I’m using solid copper 101 bar, 1/8” thick and 1” wide bus bars, similar to what you’ve posted in your setup.
I do have 4/0 welding cable as well, just in case I need it for any reason.

 

[kromc5]

Actually I’m using solid copper 101 bar, 1/8” thick and 1” wide bus bars, similar to what you’ve posted in your setup.
I do have 4/0 welding cable as well, just in case I need it for any reason.

Very nice the copper plate I think would be better solution, I have seen others using long copper plate to connect multiple batteries.

 

[Sanwizard]

Its probably just me being over cautious, but I would feel uncomfortable not being able to tell what is going on with every cell in a bank, and would set it up as 4 seperate 16s batteries in parallel at the busbar.
It will work fine both ways, but if one cell acts up, it may bring down the entire 4 cell bank, and therefore the entire battery.

Its also easier to do maintenance while keeping power on if they are seperated.
BUT, way more expensive if you are using Batrium BMS's.

 

[kromc5]

Its probably just me being over cautious, but I would feel uncomfortable not being able to tell what is going on with every cell in a bank, and would set it up as 4 seperate 16s batteries in parallel at the busbar.
It will work fine both ways, but if one cell acts up, it may bring down the entire 4 cell bank, and therefore the entire battery.

Its also easier to do maintenance while keeping power on if they are seperated.
BUT, way more expensive if you are using Batrium BMS's.

I agree with you on those points, I would be very expesive to have gone with just 16s and batriums plus all the extra cabling. That would be 12 16s banks for me just thinking about 24 runs of 2/0 cable is to much.

 

[Shawn Hayes]

Its probably just me being over cautious, but I would feel uncomfortable not being able to tell what is going on with every cell in a bank, and would set it up as 4 seperate 16s batteries in parallel at the busbar.
It will work fine both ways, but if one cell acts up, it may bring down the entire 4 cell bank, and therefore the entire battery.

Its also easier to do maintenance while keeping power on if they are seperated.
BUT, way more expensive if you are using Batrium BMS's.

I tend to agree on the point of monitoring each cell level. But yes, Batriums’ are expensive. However, I’ve been looking at cell monitors that just monitor cells, not “BMS”. This way I can monitor each cell and see what each one is doing. However, I’ve only seen a couple so far. They typically monitor anywhere from 8 to 24 cells . With me having 64 cells, that gets expensive as well.
I’m using 64 cells, however I ordered 68. So 4 will be spares, backup or in case damage occurs during shipping. So I’ll will have 4 extra that I can keep charged on stand by for issues that may arise.
Down the road I may add another single 16s pack in the future for “backup/redundancy”. That way I have more power full time and a backup option if any cell gives trouble.
This is a new off grid hone build for me, so just getting the first system operational is my goal. After construction is completed and we are living there, I’ll worry about those things when that time comes.

 

[kromc5]

I tend to agree on the point of monitoring each cell level. But yes, Batriums’ are expensive. However, I’ve been looking at cell monitors that just monitor cells, not “BMS”. This way I can monitor each cell and see what each one is doing. However, I’ve only seen a couple so far. They typically monitor anywhere from 8 to 24 cells . With me having 64 cells, that gets expensive as well.
I’m using 64 cells, however I ordered 68. So 4 will be spares, backup or in case damage occurs during shipping. So I’ll will have 4 extra that I can keep charged on stand by for issues that may arise.
Down the road I may add another single 16s pack in the future for “backup/redundancy”. That way I have more power full time and a backup option if any cell gives trouble.
This is a new off grid hone build for me, so just getting the first system operational is my goal. After construction is completed and we are living there, I’ll worry about those things when that time comes.

That is similar to my thinking, worst case I can build 2p16s as the busbars would be compatible except the back one. Even though the upfront cost is high the batrium it gives you the flexibility so I'm not limited the bms for other configurations. I also wanted to get up and testing quickly. Since it all new I hoped learn, test and get the data to see what it would ultimately take to go off grid. The next part I worry about is combing two 4p16s and hoping they work well together. Once that is complete, I plan on doing the zoom with batrium to check all my settings.

 

[kromc5]

One issue I started having during testing as the load increased so did the divergence. I had gotten early as I set the inverter and charger to high bulk charge. The goal was to get to 55.20+-, I noticed that when charging to just 80% like I wanted they would diverge more during discharge, they do charge up together being just .01 or .02 apart near the end. I have reduced the charge and changed the bypass voltage to try and get the few runners back down with the rest of the pack. Just waiting on 9 to get back to the rest. I also lowered the bypass amps so its a steady 1.49.


1, 2, 9 are always higher, 9 being the highest which is the batteries in the very back.

 

[kromc5]

I shut everything down and waited till they were all even via the batrium. I changed the settings so the charge would be minimal. Once it restarted number jump up .32 over the rest in just a few minutes. This has me stumped on why this behavior has started after running for 4 days.

 

[rhino]

I tend to agree on the point of monitoring each cell level. But yes, Batriums’ are expensive. However, I’ve been looking at cell monitors that just monitor cells, not “BMS”. This way I can monitor each cell and see what each one is doing. However, I’ve only seen a couple so far. They typically monitor anywhere from 8 to 24 cells . With me having 64 cells, that gets expensive as well.

I'm just curious if you had considered using the CellMate K9's instead of the Blockmons? If my calculations are right, to monitor (and passive balance) all 64 cells using the K9's would have been about half as much as using Blockmons. With WatchmanCore + 1000A smart shunt + 64 sets of fuses and fuse holders + 4 K9's came to $1162 to monitor all 64 cells.

Edit: if you extrapolated that out that would come to $145 for an 8 cell BMS.

 

[kromc5]

I'm just curious if you had considered using the CellMate K9's instead of the Blockmons? If my calculations are right, to monitor (and passive balance) all 64 cells using the K9's would have been about half as much as using Blockmons. With WatchmanCore + 1000A smart shunt + 64 sets of fuses and fuse holders + 4 K9's came to $1162 to monitor all 64 cells.

Edit: if you extrapolated that out that would come to $145 for an 8 cell BMS.

The watchmon core came out not long after I purchased the v4, I actaully called back then and went with Maxine's recommendations for everything.

 

[Sanwizard]

I'm just curious if you had considered using the CellMate K9's instead of the Blockmons? If my calculations are right, to monitor (and passive balance) all 64 cells using the K9's would have been about half as much as using Blockmons. With WatchmanCore + 1000A smart shunt + 64 sets of fuses and fuse holders + 4 K9's came to $1162 to monitor all 64 cells.

Edit: if you extrapolated that out that would come to $145 for an 8 cell BMS.

Holy crap! Now that is one expensive battery if the BMS alone costs that much!

 

[kromc5]

I'm just curious if you had considered using the CellMate K9's instead of the Blockmons? If my calculations are right, to monitor (and passive balance) all 64 cells using the K9's would have been about half as much as using Blockmons. With WatchmanCore + 1000A smart shunt + 64 sets of fuses and fuse holders + 4 K9's came to $1162 to monitor all 64 cells.

Edit: if you extrapolated that out that would come to $145 for an 8 cell BMS.

I really like the k9 idea due to being able to run the fans to keep the units cool. I shutdown everything today and pulled a few batteries to check them since 1,2,9 want to charge up so fast. The m8's get warm very quickly so I limit the top current. Appears you can link 4 of the k9. If I could trade up that would fantastic but highly unlikely. If the balance issues continue I may pull 1,2,9 run a full dischage with logging then do so with the with 7,10 to compare.

 

[Shawn Hayes]

I'm just curious if you had considered using the CellMate K9's instead of the Blockmons? If my calculations are right, to monitor (and passive balance) all 64 cells using the K9's would have been about half as much as using Blockmons. With WatchmanCore + 1000A smart shunt + 64 sets of fuses and fuse holders + 4 K9's came to $1162 to monitor all 64 cells.

Edit: if you extrapolated that out that would come to $145 for an 8 cell BMS.

Actually I did consider the K-9, however the K-9 is still very new. I only bought 16 Blockmons, 1 each for each pack of 4 cells. The idea being each Blockmon will balance a pack of 4 if needed. I hope that works as planned.....
Batrium said they did not yet know how much active/passive balance the K-9 would do yet. So that made my decision. If the 16 Blockmons don’t work out, I figure I can always replace the Blockmons with the K-9 once it’s a little more established, once I see how the Blockmons perform. Therefore only buying 16 helps on the budget too, if it doesn’t work.

 

[kromc5]

Actually I did consider the K-9, however the K-9 is still very new. I only bought 16 Blockmons, 1 each for each pack of 4 cells. The idea being each Blockmon will balance a pack of 4 if needed. I hope that works as planned.....
Batrium said they did not yet know how much active/passive balance the K-9 would do yet. So that made my decision. If the 16 Blockmons don’t work out, I figure I can always replace the Blockmons with the K-9 once it’s a little more established, once I see how the Blockmons perform. Therefore only buying 16 helps on the budget too, if it doesn’t work.

It will not be as high vs the m8 but a future firmware update will bring it 14.9ah.

 

[solardad]

I shut everything down and waited till they were all even via the batrium. I changed the settings so the charge would be minimal. Once it restarted number jump up .32 over the rest in just a few minutes. This has me stumped on why this behavior has started after running for 4 days.

@kromc5 i believe what you encountered is “normal” cell deviation for lifepo4 cells, at the top and bottom of the curve, above 3.375 and below 3.0 volts the cells will tend to swing out of balance (increased delta). There is very little available power above and below those voltages and not worth the effort I believe. My charge/bulk rate is 54.6v while my float is 53.8v for a similar sized bank two 2p16s banks (64 cells) and my delta is usually between .01 to .03mv.

 

[solardad]

Actually I did consider the K-9, however the K-9 is still very new. I only bought 16 Blockmons, 1 each for each pack of 4 cells. The idea being each Blockmon will balance a pack of 4 if needed. I hope that works as planned.....
Batrium said they did not yet know how much active/passive balance the K-9 would do yet. So that made my decision. If the 16 Blockmons don’t work out, I figure I can always replace the Blockmons with the K-9 once it’s a little more established, once I see how the Blockmons perform. Therefore only buying 16 helps on the budget too, if it doesn’t work.

The M8s only passive balance at 1.75a I believe per cell block so if you have 4 in parallel then that is 1120ah for that Little M8 to manage. I would look to active balancer if you want to use the upper end of the curve with these cells.
Here is a Very good review of a cheap active 5a balancer. I would use them in conjunction to the Batrium.