[RE-wrenches] LFP Inter-Battery Communication

Sat May 17 09:40:15 PDT 2025

Good info Maverick on the 3 hours. From Discover rack batts (5) & 
Schneider

  The closed loop charge voltage is around mid to high 55V, the current 
will only decrease once the target charge voltage is reached.
  You can see the target charge voltage on both lynk II and Schneider 
side.
  This will not damage the battery and it is beneficial for the batteries 
since balancing only kicks in usually  at the very top.

Dave Angelini Offgrid Solar
"we go where powerlines don't"
    [1]https://offgridsolar1.com/ [2]  [1]
e-mail  offgridsolar at sti.net
text 209 813 0060

On 2025-05-17 7:49 am, Maverick Brown via RE-wrenches wrote:

> Jason,
> 
> I think it is valuable to have SOC information available if you also 
> have an InsightHome device that can show the SOC data for reference 
> etc. For legacy inverters, voltage still makes the decisions.
> 
> I don't know of any battery that communicates together to balance 
> between individual battery entities. That still leaves the necessity to 
> charge via voltage high enough to get all batteries to high and similar 
> SOC.
> 
> The E-BOX says via Pylontech protocol that its battery voltage range is 
> 46.5V to 56.8V, so I think 48V LBCO is fine and certainly 44 is too 
> low.
> 
> There is a ".8" version of battery firmware and a ".16" version. I can 
> send you the .16 version that I have (SPBMS16SRP2205V1.5.18.C16). I use 
> HyperTerminal to install the software and it is the absolute easiest 
> battery to view the details using the Pytes USB to Serial cable (other 
> cable brands could also work). HyperTerminal was provided free by 
> Pytes. I can send you that as well. A lot of this might still be on 
> their  website.
> 
> I lieu of having a Pytes Hub to stack the existing bank as multiple 
> groups of 10 batteries, you could upgrade each battery to .16 firmware 
> and make two communicating stacks of 10 that don't communicate 
> together. If you have InsightHome, you can wire the CAN port of the 
> left 10 to Insight and the RS485 port of the right stack to Inight and 
> make "two battery banks" show up in Insight. On the Pytes, the CAN RJ45 
> Blue pair is CAN and the Orange Pair is RS485 (from the RS485 port). If 
> you have InsightFacity you can use both CAN ports. CAN devices show up 
> automatically and RS485 device need to be setup via InsightLocal / 
> Setup / Device Detection / Detect Device / RS-485: 1 to 10.
> 
> On the Charge Controllers, I would set Absorb to 55.2 for 3 hours.
> 
> I even started using EQ at 56.0 on some systems.
> 
> Good luck today!
> 
> Maverick Brown
> Off-Grid Solar Commander since 2006
> Maverick Solar Enterprises, Inc.
> * Solar Commander Remote Power
> * SunFlow Systems Cathodic Protection
> maverick at mavericksolar.com
> 512-460-9825
> 
>> On May 16, 2025, at 6:22 PM, Jason Szumlanski via RE-wrenches 
>> <re-wrenches at lists.re-wrenches.org> wrote:
>> 
>> The advantages of closed loop communication between LFP batteries and 
>> inverter systems are pretty obvious. But when you are operating in an 
>> open loop because you are working with a legacy inverter that does not 
>> support battery communication, how important is it for batteries to be 
>> wired together?
>> 
>> I started contemplating this today when I ran into a Pytes stack of 20 
>> E-Box 48100R (5kWh) batteries. Whoever installed them wired all 20 in 
>> a single communication daisy chain. Come to find out, this version of 
>> the battery only supports 8 or 16 in a communications network. The 
>> bank is connected to a couple of XW+ inverters, so it is operating 
>> based on voltage. The owner must have had to use an unconventional 
>> method to turn the batteries on, because typically you would only 
>> press the switch on the master battery. In this case, that doesn't 
>> work because the communication chain is broken at some point.
>> 
>> The reason for my visit was the battery is sitting at 43 volts because 
>> the generator didn't start and the low battery disconnect was set to 
>> 44 volts, well below the 49 volts recommended by Pytes. Side note:  I 
>> could not set the low battery cut out higher than 48V with these 
>> inverters.
>> 
>> I was there to get these jump started with a Chargeverter. I rigged it 
>> up and got things going, but various batteries were alarming out. 
>> Ultimately I just disconnected the communication cables on all the 
>> batteries and they all started charging from the Chargeverter which 
>> was connected to the common bus. Awesome!
>> 
>> So back to the original question... Are the batteries really doing 
>> anything in terms of balancing when they are connected in a 
>> communications daisy chain when they are not enclosed loop 
>> communications with an inverter? How important is the communication 
>> anyway? And in this case, assuming that the maximum batteries in a 
>> communication chain is eight, I would probably be better off setting 
>> up four separate communications with four master batteries in groups 
>> of five. Again, I'm not sure how important that is in terms of 
>> balancing. What if I had different quantities per communication group? 
>> They're not talking to each other anyway!
>> 
>> Not to muddy up this thread, but I will say that the Chargeverter 
>> saved the day. Within 20 minutes, I was able to get the inverters 
>> turned on and the SCP to help me identify what went wrong. Then I 
>> turned on the inverters and got them charging the batteries 
>> simultaneously with the Chargeverter and solar. It really just needed 
>> a jump start! I had rigged it up in a way that I could easily do this 
>> and then safely disconnect the Chargeverter while the rest of the 
>> system continued to charge the batteries. It was my first experience 
>> with this little gem, and I'm happy to have it in my toolbox now.
>> 
>> Tomorrow I am going back to restart the charging process and hopefully 
>> get the batteries up to 100%. I also plan to check the firmware, which 
>> I am almost positive is mismatched in this stack of batteries. All of 
>> my off-grid systems are a boat ride away, so I'm going to pretend it's 
>> a weekend and I'm not working. Haha.
>> 
>> Jason Szumlanski
>> Florida Solar Design Group  
>> _______________________________________________
>> List sponsored by Redwood Alliance
>> 
>> Pay optional member dues here: http://re-wrenches.org
>> 
>> List Address: RE-wrenches at lists.re-wrenches.org
>> 
>> Change listserver email address & settings:
>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>> 
>> There are two list archives for searching. When one doesn't work, try 
>> the other:
>> https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/
>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>> 
>> List rules & etiquette:
>> http://www.re-wrenches.org/etiquette.htm
>> 
>> Check out or update participant bios:
>> http://www.members.re-wrenches.org
> 
> _______________________________________________
> List sponsored by Redwood Alliance
> 
> Pay optional member dues here: http://re-wrenches.org
> 
> List Address: RE-wrenches at lists.re-wrenches.org
> 
> Change listserver email address & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
> 
> There are two list archives for searching. When one doesn't work, try 
> the other:
> https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/
> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
> 
> List rules & etiquette:
> http://www.re-wrenches.org/etiquette.htm
> 
> Check out or update participant bios:
> http://www.members.re-wrenches.org

Links:
------
[1] http://members.sti.net/offgridsolar/
[2] https://offgridsolar1.com/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20250517/cb5919cb/attachment.htm>