Multiplus-II configure for LiFePo when using Lynx Smart BMS?

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Ingo Pfeiffer asked Sep 6, '21

Multiplus-II configure for LiFePo when using Lynx Smart BMS?

Hi

I have installed 2x200Ah Victron Lithium Smart batteries via Lynx Smart BMS and Lynx Distributor to Multiplus-II 12/3000/120-32. I have tested the inverter function but not yet the charging due to below question(s). Additional info: There is no GX/Cerbo in my system and I intend to just use the Victron Connect IOS app.

Now to my question:

The manual for Multiplus-II states in chapter 2.3 a lot of specifics for lead acid/gel batteries and also in chapter 5 informs that the charging function is preconfigured for AGM/Gel batteries.

Chapter “2.3.2 Li-ion batteries” then only states: “Victron LiFePO4 Smart batteries: Use the VE.Bus BMS”…

—> can you please explain

a) if the Lynx Smart BMS (is this a VE.Bus BMS??) will control the charging coming via “Multiplus on shore power” automatically and correctly for the Lithium Smart batteries and there is NO need for a change of the Multiplus’ charger configuration

or

b) if the configuration of the Multiplus needs to be changed (using PC and MK3-USB connector)?

In addition, I hope/expect the Lynx Smart BMS, as it receives the battery temperature info, will stop charging when batteries reach 5C!? please confirm this assumption as well if possible.

Thx for reply

Multiplus-II Lithium Battery BMS VEConfigure 3

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Answer 1 · 2021-09-06T20:38:54Z

Matthias Lange - DE answered · Sep 06, 2021 at 08:38 PM

a) the Lynx Smart BMS don't have a VE.Bus only VE.Can. I would recommend you to add a GX device or at least connect charge and load disconnect from the BMS to the Multi and program it to two signal BMS.

b) you need a MK3 Interface to change the settings of the MultiPlus

Without any communication to the MultiPlus or any other load/charger there is no way for the BMS to stop the charging. The only thing that the BMS can do is to open the contactor and disconnect the battery but I'm not sure if it will do that in case of low temperature.

As mentioned above I strongly recommend you to add some kind of communication between the BMS and loads and charging sources.

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Ingo Pfeiffer commented · Feb 09, 2022 at 04:48 PM

Hi @Matthias Lange - DE (sorry for spamming you by tagging... tschuldigung... ;-)...)

Long time since your reply, and now I have a follow-on question:

for a) I plan to forward the Lynx-provided ATC-signal to the ATC-relay of the Multi. That should do the needful without GX-device, correct?

for b) I still have not fully understood, if I need to change the MultiPlus setup to Lithium battery or not. I cannot come fully to an own conclusion from reading the manual for MK3-USB/VE.Bus Configuration Guide, chapter 10.4.10 Lithium Battery Mode (link below), which case A), B) or C) would be applicable in my setup without GX... assume though I might be case B) or C)

Can you explain more what needs to be done to safely use the Multiplus-II charger in my setup?!

In B) it is stated: "Victron V12.8 and 25.6V batteries, requiring a VE.Bus BMS - Please use VEConfigure instead and install the VE.Bus BMS Assistant, as well as check the Lithium battery checkbox".

--> you wrote Smart Lynx has VE.CAN not VE.Bus... so, where would the VE.Bus BMS Assistant be installed? On the MultiPlus?

In C) it is stated: "Intelligent batteries, connected to a GX-device with DVCC enabled - Checking or not checking the box doesn’t matter; it has no effect. In systems with such a battery, all charger settings are overridden by parameters coming from the CAN-bus. Examples are Victron 24V Lithiums with a Lynx BMS, BYD, Pylontech, MG Electronics, Freedomwon, Redflow, and others.

--> Is Smart Lithium 12.8V battery an "Intelligent Battery"? Is the "connection to GX-device" mandatory? The example "Victron 24V Lithiums with a Lynx BMS", isn't that my setup but 12V and no GX-device??

I would highly appreciate further clarifications on this... big thanks for spending time to understand and comment from your experience/understanding point of view

https://www.victronenergy.com/media/pg/VE.Bus_Configuration_Guide/en/description-of-settings.html#UUID-ab2f26e1-6e55-c3b6-5ced-12812bc0828e

Thx - Ingo

PS - for the low-temp disconnect, I learned this winter, that with ATD=allowed and ATC= disallowed and Lynx contactor closed, thus onboard-system powered up, the Lynx contactor opens and disconnects the batteries from the onboard system when my buckboost is starting to charge at low battery temp (not connected to ATC-signal yet). I would guess the same behavior, Lynx contactor opening up, will be happening when ATD=disallowed. Not been in that situation yet...

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