Hello jmagg, @jmagg
Welcome to the forum. In any case, it’s a good idea to familiarize yourself with the Victron world and familiarize yourself with it. I myself have an installation, albeit one that’s currently running smoothly and with devices that are a good five years old (1x Multiplus II GX, 2x Multiplus II – 3-phase ESS), and I’m facing the same problem: how do I get to the 2025 version?
What I know so far is that my original, childishly naive idea of being able to directly start an upgrade process using a serial number or in combination with a known firmware version, via a program, a portal, or a database, isn’t possible.
First, you come across the mantra-like and repeatedly repeated argument that you should only perform an update if you have problems. Fortunately, this doesn’t apply to you, because when performing a new installation, it’s generally recommended to start with the latest possible firmware version.
I’ve also heard and read that the size of the processor is somehow crucial for the upgrade process. I don’t understand why this fact can only be determined through reverse engineering and opening the device. It may be that I’m simply incapable of asking the right questions or searching in the right places in the Victron web universe.
Based on my knowledge, and I admit that it may be flawed and inaccurate, and knowledgeable experts are welcome to correct me, you definitely need an MK3-USB interface. This allows you to establish a connection between your Multiplus and a Windows PC and perform the upgrade, provided you have previously found the appropriate firmware in the Victron universe.
To access the correct firmware version, you need access to the Victron Professional Portal. Access is available to any user, not just those who are professional users, as the name suggests. So don’t be shy, please register!
After registering, you will have access to previous and current firmware versions. There, you’ll find a PDF file called “manual-VE.Bus-firmware-versions-explained-EN.pdf” as well as a text file called “VEBus firmware numbers.txt,” which contains a kind of identification number for your model. The difficulty here is figuring out which model you actually have. In addition to the obvious and understandable distinctions, there are other options besides the processor size, such as external sensors with different power ratings. All of these factors make it almost impossible for a casual user like me to select the correct identification number and then use it to select and download the correct firmware file.
Otherwise, Victron email support simply refers you to the dealer, who should do it for you.
I don’t know of any other upgrade method, and even after asking, I haven’t been able to find any other way to upgrade. In my opinion, this is unfortunately very cumbersome and requires knowledge of many additional, often unknown, facts. It seems out of date to me in 2025. However, this may be due to the fact that Victron has created a vast array of devices for many different markets and applications over many, many years.
In any case, it’s worth getting to grips with them, because once you have the devices running, they do exactly what they’re supposed to for a long time without any problems. I can certainly confirm this for my installation, which is over five years old.
Kind regards - Ewald
