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Summary
EG4 48V batteries that have been sitting idle connected to an EG4 inverter will have a small parasitic draw that is too low powered to be registered as power leaving the BMS. Over time this parasitic draw can drain the battery of stored energy while in an idle state, without the ESS recognizing the change to the SOC of the system.
Customer Impact
Affected customers may experience a rapid drop in battery SOC when turning on loads that require a greater draw from the battery. In some instances, this rapid drop can push the SOC under the shutdown percentage, leading to complete system shutdown and loss of power.
Resolution
The latest 48V battery Firmware from EG4 has been designed to perform a periodic voltage check of the internal battery cells to update system SOC. This voltage update will trigger an SOC decline and subsequent recharging before bulk SOC decays to a shutdown level. Affected customers should update to the latest FW as listed below:
314Ah Indoor: Z03T17
280Ah Indoor and Outdoor: S02T25
Lifepower4 V2: S02T34
LL-S 48V: S02T34
Posted : January 14, 2026 2:52 pm
I updated all 4 of my indoor 280ah batteries to this firmware version and it completely destroyed the BMS reporting data to the cloud server. EG4 support does not have answers on this after spending an hour and a half with them on a call.
Posted : January 20, 2026 4:40 pm
@solargear I also experienced the same issue when completing an upgrade yesterday evening on 3x Indoor Wall Mount 280Ah, and I was planning to contact support. Thank you for checking in with them - I will probably still do so just to log the issue.
I did confirm that my inverter still treats the battery system as having the same capacity and charge/discharge performance as the 3x batteries. I'm continuing to operate while keeping an eye out for any odd behavior and waiting for a fix.
Posted : January 21, 2026 12:25 am
Well, I am not the only one! I have 2 batteries but only 1 showing up with the same weird characters for the battery. The configuration shows 2 batteries but the monitor / BMS reporting is trashed.
Glad you posted this as this is installed off-grid at our cabin 2 hours away and I was going to drive up tomorrow to try to figure this out.
I noticed your version is 2.28 but the firmware update was 2.11 I thought?
Hopefully they can figure this out quickly!!!
Posted : January 21, 2026 1:23 am
Ok, stuff like this drives me crazy. Drove the 2 hours to the cabin...loaded the oldest versions of the firmware both RS232/RS485 that I could find for the Indoor Wallmount 280AH batteries.
RS485 -> Z02T04 (which is what I think they were before the update to Z02T11)
RS232 -> S02T11 (not sure which version they were before the update to S02T25)
Both batteries are showing again in the monitor. So a workaround until they fix the updates which toasted things perhaps?
Hope this helps!!
Thanks.
Posted : January 21, 2026 5:22 pm
EnergyBalanced reacted
@yooperjay Thank you for testing out that you can update the firmware with old versions (and supplying the files). I had a feeling that was possible but didn't want to try it out 😆 Also, I believe 2.11 was the Indoor FW version and 2.28 is the All Weather version.
I think I'm going to leave the current versions in and verify whether it helps with my SOC/voltage mismatch caused by parasitic loads. I'm local to my batteries so I can look at all the parameters in person if I need them (rarely do). For now, it's just messing up my Home Assistant reporting.
Posted : January 22, 2026 6:32 pm
Topic starter
Thank you for bringing this to our attention. We are actively investigating the issue and working toward a resolution.
Posted : January 23, 2026 6:11 pm
PowerUp reacted
Topic starter
@solargear @energybalanced @yooperjay
Ensuring that both the RS232 and RS485 firmware are updated to the latest versions should resolve this issue.
Posted : January 23, 2026 6:32 pm
PowerUp reacted
@solargear @energybalanced @yooperjay
Ensuring that both the RS232 and RS485 firmware are updated to the latest versions should resolve this issue.
This does not solve the issue. Both firmwares were updated to the latest and did not fix anything. I also tried to update the rs485 firmware with the allweather battery which resulted in the same issue. There is a serious disconnect at EG4, support is telling me that a new battery firmware will be released soon? Please explain?
Posted : January 23, 2026 6:58 pm
PowerUp reacted
@eric
Well, I believe updating to the latest firmware broke things which led us all here.
This is what I updated to which broke the monitoring ... weird characters, not showing the battery info or the proper number of batteries (screenshots from all of us posted in this chat).
EG4 WallMount 280Ah Indoor Battery
RS232 Firmware- S02T25
RS485 Firmware Z02T11
I will redownload the latest firmware from here and try again...
Posted : January 23, 2026 7:31 pm
PowerUp reacted
We just joined your Party. Our remote clients batteries are now BRICKED. S02T25 & Z02T11 on 280AH wall-mount.
The 12kPv system teases us by showing only one battery and switching every so often to only show the other.
With the strange names for the batteries. Seems that the path to recovery is to send a truck and schedule with the client to roll back the firmware.
It is sad that Eric @eg4eric takes all the heat for these issues and doesn't have the support of engineering.
Posted : January 26, 2026 4:31 pm
EG4 Eric reacted
Topic starter
@solargear
We will ensure this gets corrected. The latest firmware for all batteries is available on each product page. We were advised that installing both firmware updates should resolve it; however, if some customers are still experiencing the problem, we will continue to look into it and work toward a permanent solution.
Posted : January 26, 2026 8:20 pm
PowerUp reacted
Topic starter
@powerup
I apologize for the inconvenience! Our team is aware of this issue and are currently working on resolving this issue.
Does the monitoring show the correct battery capacity?
Are the LCD screens working?
Posted : January 26, 2026 8:25 pm
Are the LCD screens working? Yes, screenshots attached for both my batteries showing Z02T11
Does the monitoring show the correct battery capacity? No, not really only showing 1 battery in my case at 280Ah (see post above from January 20, 2026 8:23 pm). It seems an issue with the monitor / battery information. It does seem the "system" still thought it had 2 batteries / capacity (just looking at usage and the data logs) but the monitor page was not recognizing the correct number of batteries and showing weird characters in the information (which can be seen in the screenshots in this thread).
Posted : January 26, 2026 8:42 pm
If you look at the mobile app, the correct battery capacity shows there. For my own system, I have 4x indoor batteries and it shows as:
Batt Parallel Num: 4
Batt Capacity: 1120Ah
BMS Limit Charge: 560 A
BMS Limit Discharge: 800 A
Posted : January 26, 2026 8:50 pm
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