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The insurance policy on your lithium bank
A BMS watches every cell and steps in before over-charge, deep discharge, or cold-weather charging can do permanent damage. These are the marine-grade units we trust with Victron Smart and NG lithium banks — and the MG controller for bigger builds.
Swipe the table sideways to see every column →
| BMS | Works with | Key point | Best for | From |
|---|---|---|---|---|
| Victron SmallBMS | Smart & NG lithium | Simple charge/load disconnect control with pre-alarm | Compact DC systems that want clean, basic protection | $49.30 USD |
| Victron VE.Bus BMS & BMS V2 | Smart & NG lithium | Controls MultiPlus/Quattro directly over VE.Bus | Systems built around a Victron inverter/charger | $117.30 USD |
| Victron Smart BMS CL 12/100 | Smart lithium, 12V | Built-in 100A alternator current limit | 12V boats charging lithium straight from an alternator | $122.40 USD |
| Victron Smart BMS 12/200 | Smart lithium, 12V | 200A system BMS with battery and load ports | Higher-current 12V systems and bigger loads | $186.32 USD |
| MG Master LV | MG lithium, 24–48V | System master controller, 400/600/1000A ratings | High-power MG Energy builds and refits | $849 USD |
The BMS pairs with the battery line, so start from your bank: Victron batteries here, and note that drop-ins like the SuperPack and Epoch carry their BMS inside. A BatteryProtect adds low-voltage load shedding to any bank.
How to choose, in three questions
What your bank requires, what your system looks like, and how charging comes in.
Does my battery even need one?
Drop-in batteries (SuperPack, Epoch, most motor packs) have a BMS sealed inside — nothing to add. Victron's Smart and NG lithium deliberately use an external BMS so protection can command the whole system, not just the battery. If you're running Smart or NG cells, a BMS from this page isn't optional.
What's in the system?
If a MultiPlus or Quattro is the heart of your boat or rig, the VE.Bus BMS is made to command it directly. Simpler DC-only setups do fine with the SmallBMS and its pre-alarm. Bigger MG-based installations run through the Master LV. The BMS should match how your system is actually wired.
How does charging arrive?
Alternators deserve special care with lithium — a hungry bank can work one to death. The Smart BMS CL 12/100 solves it with a built-in 100A current limit; on other setups a DC-DC charger between alternator and bank does the taming. Tell us how you charge and we'll close that loop.
Why buy from Blue Marine
True Blue Victron distributor
Warranty and setup support handled by us, not a ticket queue.
ABYC-certified advisors
We match BMS, battery, and charge sources so protection actually protects.
Free US shipping over $49
Fast shipping from Seattle and 60-day returns on non-lithium items.
Real people, real boats
Call (800) 628-6306 Mon–Sat.
Not sure which BMS your bank needs?
That's a five-minute conversation. Tell us your batteries, inverter, and charge sources — we'll name the exact BMS and the wiring approach that fits.
BMS FAQ
What does a BMS actually do?
It monitors the cells and acts before harm: stopping charge when a cell runs high or gets too cold, shedding loads before deep discharge, and raising an alarm first when possible. Lead-acid forgives abuse by dying slowly; lithium needs a guardian that reacts in the moment — that's the BMS.
Why don't Victron Smart and NG batteries have it built in?
By design. An external BMS can command the rest of the system — telling the MultiPlus to stop charging, the alternator path to back off, and loads to shut down — instead of just disconnecting the battery internally. For integrated boats and rigs, that whole-system response is the stronger protection.
What's different about the Smart BMS CL 12/100?
It has a built-in 100A current limit on the alternator input. Lithium banks accept charge so eagerly they can overheat an alternator that was sized for lead-acid; the CL meters that current without extra hardware. If you charge from an alternator on a 12V boat, it's the tidy answer.
What happens when the BMS trips?
Whatever caused it stops: charging halts on a high or cold cell, loads disconnect on a low one. Most trips clear themselves when the condition recovers, and pre-alarm outputs (SmallBMS included) can warn you before a shutdown so you're never surprised at anchor.
Do I still need fusing and a battery switch?
Yes. A BMS protects cells; fuses protect wiring and people. Every bank still wants proper overcurrent protection and a way to isolate it — see DC distribution & fuses, and check each device's datasheet for recommended sizes.