EG4 read/write cable

Storage14 said:

The "silence" of Signature Solar is quite AMAZING!

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Ah, sorry, this post was from before my time.

Yes they're the same cable. You can check that the pinout is in pins 1&2 to verify this.

I'm stumped...perhaps someone can shed some light. I have a USB cable and I'm fairly certain - from Signature Solar tech support - that I have the RJ45 end correctly wired with the black on pin 1 and the red on pin 2. Their old cable used the green and white pins but that evidently doesn't work on the newer batteries/software.

What no one is discussing is the USB-A connector...the part that you stick into your computer. Some people loosly call it a "dongle" and I'd love to know if there is something in that. Originally, I connected using my own DIY cable (see below) that was cut from a USB-A to USB-C cable with the USB-C end cut off and a RJ45 was connected "correctly" to that cable. But, the device manager (Win11) said my COM port was 4 and the BMS_test software would only populate COM 1 & 2 in their dropdown for "Port Number". I stuggled with this online with SS for hours. Once they saw a picture of my RJ45 connector correctly pinned, they stopped investigating my cable.

With no solution found, I decided to try the inverter cable (shipped to me from SS) with the BMS_test software. I plugged in the USB-A "dongle" end to my computer - IMPORTANTLY, I did not have the RJ45 end of the cable plugged in to the battery - and when I plugged it into my computer, I got a notification from Windows. That stumped me. How can connecting a cable with open ends notify of anything to anyone. Additionally, after this notification, the BMS_test software populated their "Port Number" dropdown with my COM 4. Very strange!! There is something in that cable's dongle!

There must be something in that "dongle" that is critical to Windows and the BMS_test software. I now see clearly that all working cables in messages above and elsewhere always have a big dongle at the USB-A end of the cable. No one seems to be talking about this end, but it seems more that just a USB-A connector.

Can anyone explain this and why no one is talking about it? Here are my two USB-A connectors.

SignatureSolarJess said:

Ah, sorry, this post was from before my time.

Yes they're the same cable. You can check that the pinout is in pins 1&2 to verify this.

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I think this cable should be included with a battery purchase at no cost, if the customer is to update the firmware to the most current version.
or Signature Solar to update all batteries to most current version prior to delivery.
The same should be for all inverters update to the latest firmware.

I've been down this wormhole for a few weeks and I can share what I know. Not an expert so don't trust me 100%

1) Yes, there is a chip in the USB end of these RJ45 to USB cables that allow it to communicate with the computer. I don't think you can just start hacking up USB cables and have your computer recognize anything.

2) There are two cables that are needed to get a EG4 PowerPro fully updated, and right now the "traditional battery firmware" files are missing from the available firmware download link on the EG4/SS website.

Cable #1 is a USB to RS-485 cable. This will go in the RS-485/CAN port and USB into a computer, and if a "traditional firmware" were available for download, you would use it to flash that firmware.

Cable #2 is a USB to RS-232 cable. This will go in the BAT COM port and USB into a computer, and the "heater logic firmware" will be updated using this cable/port combo.


It's all a bit of a mess right now. I was shipped an RS-485 cable with my new PowerPro. My first PowerPro didn't come with either cable. SS is shipping me a RS-232 cable after requesting one here/from service. From there I can get the heater logic firmware updated, but we are still lacking the other half of the files needed to fully update our batteries.

Scat said:

I think this cable should be included with a battery purchase at no cost, if the customer is to update the firmware to the most current version.
or Signature Solar to update all batteries to most current version prior to delivery.
The same should be for all inverters update to the latest firmware.

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Yes! These are included with our units, if anything is missing, please don't hesitate to reach out and we will get that sent out to you without charge!

Storage14 said:

The "silence" of Signature Solar is quite AMAZING!

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I've emailed them in the past and got radio silence as well, however calling them is an entirely different experience. Going forward, I will be calling first, emailing last.

This is crazy! I've spent $30K and can't get this cable thing worked out. I was sent an RS485 cable and upgraded the RS485 related firmware. I called SS and they are sending me a USB RS232 cable. I asked for the pinout to stay on schedule with my turn-up, but they sent me Pin 1 & 2, which doesn't work...and the documentation shows Pin 4 & 5. I pinned it 4 & 5 and 5 & 4, but it doesn't work either. I'll wait to upgrade the Heater Firmware when I receive the magic cable. Would be nice if they would communicate/deliver this better. Very confusing.

SolarCzar said:

This is crazy! I've spent $30K and can't get this cable thing worked out. I was sent an RS485 cable and upgraded the RS485 related firmware. I called SS and they are sending me a USB RS232 cable. I asked for the pinout to stay on schedule with my turn-up, but they sent me Pin 1 & 2, which doesn't work...and the documentation shows Pin 4 & 5. I pinned it 4 & 5 and 5 & 4, but it doesn't work either. I'll wait to upgrade the Heater Firmware when I receive the magic cable. Would be nice if they would communicate/deliver this better. Very confusing.

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Hi! I’m so sorry you’re having trouble! If you’d like to dm me your email address, I will get this escalated to ensure this is taken care of!