[RE-wrenches] LFP Inter-Battery Communication

Sat May 17 16:13:52 PDT 2025

Thanks Maverick. I do have the cable and the software from Pytes. I checked
all batteries and there were all C version and on .8 Firmware. Pytes also
sent me the .16 version file, but I elected to just connect them in four
stacks of 5. This will make it easier to upgrade later because I believe
you only need to upgrade the host batteries and the slaves will all update
automatically.

The Pytes software is pretty great. When they are in a comm string, you can
see all connected batteries from the Host in the same interface. You can
see all kinds of real time data and historical events.

After I got the 20 jump started and charging today I went to the neighbor's
house with a stack of 8 Pytes. They were not coming alive when connected
together. I connected to the Host battery and the software found only 7
batteries. This stack has two C versions on .8 and six B versions on
1.3.17, which is compatible with C version when thety are on .8 (but not if
they are in .16).

It turns out that the one battery not taking was a B version, and the only.
Thing in the Pytes software that is different Is this battery has no
"Barcode" associated with it. It lists the Barcode as ---. I have no idea
what that means, but given that it is the only battery without this field
populated, it has to have something to do with the communication chain
being broken. I tried to place it at the end of the communication chain and
also to use it as the host, and none of that worked. I ended up leaving
seven connected together and the bad battery just on its own with no comms.

I couldn't reach Pytes support, so I'm waiting on answers.

I'm thinking that this communication glitch is what was causing the Midnite
AIO to shut off due to a battery absent error occasionally. In the battery
Event logs, I can see an ADDR fault, so that suggests that the stack of
batteries shut down due to an address error, and then probably started back
up, but the AIO remained off until turned on with user intervention.

Not to jumble this up with the other thread about Solar Assistant, but I
wonder if you connect multiple stacks of batteries to SA if it would
aggregate them and average the SOC. I'm also curious if the individual
battery data is viewable.

Jason Szumlanski
Principal Solar Designer | Florida Solar Design Group
NABCEP Certified Solar Professional (PVIP)
Florida State Certified Solar Contractor CVC56956
Florida Certified Electrical Contractor EC13013208

On Sat, May 17, 2025, 12:23 PM Maverick Brown via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> Jay,
>
> Oh yeah…
>
> Logic: Jason’s customer has 20 batteries in parallel. Longer Absorb will
> help let them all catch up… 3 hours is not a fact, just a starting point.
> It could be lower or higher. Another consideration is the XW Charge
> controller voltage calibration verses what the batteries think they have.
>
> Hopefully, Jason has the USB Serial cable and can investigate the
> individual batteries.
>
> ;-)
>
> Maverick
>
>
>
> 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 17, 2025, at 10:21 AM, Jay <jay.peltz at gmail.com> wrote:
>
> Hi maverick
>
> Can you explain the logic of 55v for 3 hrs?
>
> Thx
> Jay
>
>
>
>
>
>
> On May 17, 2025, at 7:50 AM, Maverick Brown via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> 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
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