When designing a Victron lithium battery system there are so many BMS options to choose from that it can become a bit confusing. This article is a guide to selecting the right one for your project.

Small BMS
Suitable for the smallest simplest systems, this is the most basic model. For use with systems from 12 to 48 volts.  It does have a pre-alarm output to warn of impending system shut down. A typical use would be in a solar powered remote security camera installation.  This BMS requires Battery Protects to control DC devices
This has similar features to the Small BMS.  It adds the VE Bus port and means that this BMS can directly control a MultiPlus or Quattro using the VE Bus Assistant.  It also means that the BMS will show up on the Cerbo GX and can be seen remotely on the VRM.  This is the only BMS that can be seen on the VRM.  This BMS can be used in any system from 12 to 48 volts and gets used in boats, vans and RV's.  This BMS requires Battery Protects to control DC devices
BMS CL 12-100
This is for 12 volt systems only and was designed with Sprinter Vans in mind.  It has the ability to take a measured amount of power up to 100 amps from the vehicles alternator. The alternator has to be producing more than 13 volts for this to work as the BMS will not step up the voltage. It has Bluetooth connectivity but will not show up in a Cerbo GX or remotely on the VRM. It can control a MultiPlus or Quattro remotely with the two wire BMS Assistant.  It has a pre-alarm output and can be used as a remote switch.  This BMS requires Battery Protects to control other DC devices.  This device has cooling fins because the alternator control function generates some heat,
Smart BMS 12/200
This is similar to the BMS CL 12-100 and is for 12 volt systems only, it can take power from the alternator in the same way.  It's designed with small vans in mind but could also be used on small boats.  It has Bluetooth connectivity but wont show up on the Cerbo GX or VRM. With this model you can omit the BatteryProtects for loads or charge sources up to 200 amps.  This makes for a very simplified system but it does mean that the BMS is quite chunky and weighs in at almost 5.5 Lbs.  This is particularly suitable if you want to install the 12/2000 MultiPlus because it can just be connected in without any special programming or cables.  You will still need to program the charge profile of the MultiPlus for Lithium batteries.
Lynx Smart BMS
Part of the Lynx distribution system, this BMS is for systems from 12 to 48 volts.  It is the most sophisticated and expensive model but it does contain three products in one.  As well as being a BMS it is also a battery monitor and a contactor. We are recommending this BMS for all our large marine installations but we have also sold a few for use in larger van and RV installations.  This BMS adds lots of features to the basic functions. It is designed to be used with the Cerbo GX so any alarms will show up there (but not on the VRM.)  It also has Bluetooth. It has a pre-alarm.  It has plug and play functionality when used with MultiPlus and Quattro inverter chargers. It has an auxiliary power supply for the Cerbo so it is kept alive after a system shutdown which greatly simplifies troubleshooting. When used in conjunction with the Lynx Distributor it will monitor blown fuses and report them to the Cerbo.  The contactor acts as a remote battery switch and avoids the need for any other switch. It also acts as a failsafe shutdown in the event any of the other control mechanisms fail or get bypassed or are mis-wired.  This means the batteries are always protected. This is going to be the first choice for any large or complicated installation.

I have simplified things a bit, I recommend looking at the datasheets for the individual items. There is one obsolete item that I didn't mention, the Battery Management System BMS 12/200. If you are still confused, don't worry. At PKYS we are her to help you navigate this complicated field. We can help you select the right equipment for your project. Be sure to contact us for more details.

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