question

you would only need to upgrade the MPPT module if the old module can't cope with the charging current from the new panel. The MPPT will connect to the pi via an isolated serial interface, eg the Victron VEdirect/usb cable.

If you are writing your own software to bring data into the raspberry pi over bluetooth, then you will be able to use Dbus service to transfer this data to the Venus os.

Yuo don't mention if the system voltage is 12v or 24v - the latter would be preferred for any except really low inverter power. using lithium battery instead of AGM should be no problem at either of these voltages, provided you can program the correct voltages and current limits. If you have access to the BMS data from the batteries, this can also be integrated into the Venus system.

Upgrading the inverter firmware may be a bit tricky though. If it's really old, then the VE flash program will be needed.

Thank you for your reply. That means installing LifePo4 (2 x 300ah) must be possible?

I am looking at the LiTime 12v 300Ah.

The system is 12v (Niesmann + Bischoff Flair 800i from 2013)

I have bought the MK3 usb cable which will arrive tomorrow. Installing the VE Flash can be done if that is neccesary. I work on Mac but have an old windows laptop which i think might be needed.

What steps do i need to do, first try to update the MultiPlus. How do i know which version i have and need to download and install. And how can i be sure to setup the right settings before connecting the new Lifepo4 batteries, first with an old AGM connected?

Here is the manual from the Litime battery:

https://cdn.shopify.com/s/files/1/0667/7220/5788/files/LiTime-LiFePO4_Battery-12V300Ah-US.pdf?v=1667808952

Also, do i need a booster? I read that with lifepo4 that is needed but i don’t know if i need it with the MultiPlus

Yes, you will need a windows machine, software can be found at https://www.victronenergy.com/Executables/VEConfig/VECSetup_A.exe

Once you connect the Mk3 to the usb and inverter, power the inverter on, with no loads. you can connect direct to the li battery to do this, the control circuit load is fairly small. once you have the correct settings, you can then finish the installation.

Run ve config, there is a menu option to find the software version. VE flash is an optional part of the same package.

Read:

https://www.victronenergy.com/media/pg/VictronConnect_Manual/en/firmware-updates.html

https://community.victronenergy.com/questions/74614/multiplus-compact-12200080-firmware-update-from-20.html

may also be relevant.

Problem with the LiTime 12v 300Ah is that although the BMS is self contained, there does not appear to be any communication to the BMS. this means that you won't get any warning for low voltage shut down, or overcharge shutdown - so must program system max and min voltages to give a 100mV margin - so as the system shuts off charge / discharge before the batteries turn off - they go effectively open circuit when this happens.

No, you don't need a booster. The working voltages are compatible.

hope this all helps.

Can't you configure the Multi with VictronConnect from a Mac?

The 142 firmware might need an update first however.

Thank you, i could update to v209 but that is the latest.

I can connect via VictronConnect now but i think the firmware is too old to be configures via this app. I need to do that with the old VEConfig software.

So i need to connect the LiPeFO4 batteries, than chante settings? And with a margin of 100mV?

How do i do that. Set limit for charge to for example 14.5v instead of the manual 14.6v?

The two important values are the disconnect voltages.

Next, the disconnect voltages (charging) are well above the max recommended charge voltage of 14.4 / 14.6V. However cell corrosion occurs faster at high voltages, so stick with the 14.4V. Very little extra energy will be stored in the last 100mV.

At the low end, the inverter cut off voltage should be equal or above the low voltage reconnect, so settig this to 12.5V would be good. Most damage occurs to lithium cells when over-discharged, rather than over-charging. The inverter reconnect voltage can be set to 12.8V, or as close to this as possible.

Anyone an idea what i need to setup for that type of battery? (2 pieces)

I got a reply that i don’t need a booster. But a lot of video’s i watched online say i need a booster (dc/dc charger) because otherwise i will kill the alternator. Even some examples show a booster in combination with a multiplus. Why don’t i need that?

And why do others have it?