These tables compare Li-Ion BMSs available on the market today.

This information does not constitute an endorsement of any of these companies and products.

While the information presented here is believed to be accurate, Elithion takes no responsibility for any errors.

Please send us comments, corrections and additions.

Spreadsheet of BMSs

Parametric BMS selector

Go to the Parametric BMS selector utility.

BMS types

This table explains the difference between digital and analog BMSs, and between Protectors, Balancers, Monitors, Displays and Regulators.

Reports individual cell voltages Balances the battery Requests that battery be switched off Includes switch to turn off battery Digital:

knows where

the problem is

and by how much Protector ✓ ✓ ✓ ✓ Balancer ✓ ✓ ✓ Monitor ✓ ✓ Meter ✓ Analog:

knows there's

a problem,

but doesn't know

where and

by how much Protector ✓ ✓ ✓ Balancer ✓ ✓ Monitor ✓ Regulator ✓

Prices

Digital BMSs



Digital Protectors and Balancers

Note: log scales. Sources: Digital Protectors and BalancersNote: log scales. Sources: (15)

Analog BMSs



Protectors (thin line), Balancers (thick line).

Note: log scales. Sources: Protectors (thin line), Balancers (thick line).Note: log scales. Sources: (15)

Digital protectors

Sophisticated digital technology, able to measure and report every cell voltage, to balance the battery pack, and to cut-off the battery current.

To see additional information, hover your cursor over the icons.

Company

(1) Picture

(2) Model Topology

(3) No of cells

(4) Cell shape

(5) Current Temper.

(7) Curr.

sense

(8) "Fuel

gauge"

(9) Comm.

(10) Displ.

(13) Case

(14) Chargery

China

GuangDong B series Wired,

Centralized 1~12

Any - - - - ✓

Metal Clayton power

UK No longer selling off-the-shelf BMSs; custom BMS only e-chip No longer selling BMSs Emus

(Formerly Elektromotus)

Gintautas Paluckas

Lithuania BMS Mini Wired,

Centralized 6~16 Any 45 A cont. / 100 A pk. 5 ✓ ✓ CAN (CANOpen), LIN, RS-232, Bluetooth GUI Plastic ∝

Energus

Lithuania S516 Wired,

Centralized 5~16 Any 60 A cont. / 150 A pk.

or

600 A cont. / 750 A pk ✓

✓ ✓ USART (USB / Bluetooth) CycleAnalyst

GUI (Android) Open board JTT

Vancouver, BC

Canada

∝ P-Series Wired,

Centralized 5~13 Any 25 A ✓ ✓ Open board T-Series Wired,

Master/slave 4~240 Any 1 / 4 cells 300 A

✓ RS485, RS232

GUI Metal Lithium Balance

Denmark No longer selling protector BMSs Lithium Start No longer selling BMSs RoboteQ

US

Arizona

∝ BMS1040 /

BMS1060 Wired,

Centralized 6~10 /

11~15 Any 100 A 3 ✓ ✓ CAN (CANopen), RS485, USB

-

? Ventec

France iBMS

for electric bicycles Wired,

Master/slave 10 Any 50 A ✓ ✓ ✓ CAN

RS232 - - iBMS

for scooters 18 350 A ✓ ✓ ✓ CAN - - Company

(1) Picture

(2) Model Topology

(3) No of cells

(4) Cell shape

(5) Current Temper.

(7) Curr.

sense

(8) "Fuel

gauge"

(9) Comm.

(10) Displ.

(13) Case

(14)

Digital balancers

Sophisticated digital technology, able to measure and report every cell voltage, to calculate SOC, to balance the battery pack, and to request that the battery current be shut off to protect it. Does not include a switch to cut off the battery current.

To see additional information, hover your cursor over the icons.

Digital monitors

Sophisticated digital technology, able to measure and report every cell voltage, to calculate SOC, and to request that the battery current be shut off to protect it. Not able to balance the battery pack.

To see additional information, hover your cursor over the icons.

Digital meters

Sophisticated digital technology, able to measure and report every cell voltage. Not able to balance the battery pack; does not protect the battery (does not request that the battery current be shut off).

To see additional information, hover your cursor over the icons.

Company

(1) Picture

(2) Model Topology

(3) No of cells

(4) Cell shape

(5) Temper.

(7) Curr.

sense

(8) "Fuel

gauge"

(9) Comm.

(10) Fan

drive

(11) Contac.

drive

(12) Displ.

(13) Case

(14) CasaDelGato No longer selling BMSs Ken Hall No longer selling BMSs

Analog protectors (PCM)

A protection circuit is a BMS that also includes a way to interrupt the battery current to protect the battery (unlike a protection circuit, a standard BMS must rely on external devices (charger, motor controller, contactors) to reduce or stop the battery current when the BMS tells them to)

Protection circuits usually are meant for small batteries (cell phones, laptops) as they can usually only handle a few Amps of battery current

Sources of commercially available circuit protectors for small Li-Ion batteries:



Analog balancers

Simple analog technology, just able to detect that some cell's voltage is too low or too high, but unable to report which one. Able to balance the battery.

To see additional information, hover your cursor over the icons.

Analog monitors

Simple analog technology, just able to detect that some cell's voltage is too low or too high, but unable to report which one nor to balance the battery.

To see additional information, hover your cursor over the icons.

Company

(1) Model Picture

(2) Topology

(3) No of cells

(4) Cell shape

(5) Temper.

(7) Curr.

sense

(8) "Fuel

gauge"

(9) Comm.

(10) Displ.

(13) Case

(14) Price

[US$]

(15) Thunderstruck

US, CA BMS-X Distributed Any Prismatic

M8 bolt only - - - Wire

- - $ 150 + $ 15 / cell

Regulators / equalizers / balancers

Regulators (also called "equalizers" or "balancers") are sometimes used in Li-Ion packs as a simple protection against overcharging. A regulator is required across each cell.

A regulator performs balancing during charging by bypassing charging current from the fully charged cells, so that other cells in the battery can finish charging.



Elite Power Solutions Battery Balancer. Elite Power Solutions Battery Balancer.

What regulators do:



Regulator remove excess energy from cells whose voltage is above a certain threshold, but that's all they do

What regulators don't do:



Regulator can't keep individual cells in a battery from overcharging

Regulator don't monitor the entire battery, and don't report on its status

Regulators do not protect a pack from undercharging

Regulators are not able to tell the charger to stop charging: a human has to keep an eye on the regulators (which usually have LEDs) and shut down the charger

Regulators cannot not tell external devices to slow down or stop charging or discharging; therefore, a pack with regulators can still be under-charged, and overcharging may damage the regulators

Regulators can't protect themselves from overheat: they will be damaged if a CCCV charger's end current is higher than the regulators can bypass

EXCEPTION: The EV West bottom balancer actually does things the other way around:

Instead of top balancing, it bottom balances: it removes energy from a cell until it's empty

Instead of being permanently mounted on a cell, it is used only once, at manufacture, to empty a single cell at a time

Instead of being installed in addition to a non-balancing BMS, this bottom balancer is intended to be used without any BMS at all

Sources of commercially available regulators for Li-Ion cells:



Linano - Prismatic cell - Europe

CBM1 - Cell Balancing Module - 3.60V- 1.7A - Europe

Hot Juice Electric - US - Texas. No longer made.

Elite Power Solutions Battery Balancer sold by Electric Blue Motors - regulator for a single LiFePO4 prismatic cell For 90 Ah prismatic cells Probably on the order of 200 mA balance current Fixed 3.7 V voltage Not ideal for LiFePO4 cells: the shunt voltage is a bit too high Won't work with Thundersky cells: the shunt voltage is too low Won't allow LiPo and cobalt lithium cells charge fully: the shunt voltage is too low $ 13 each

Bat Guard , by LL Labs (no website), sold by Anida in Dallas, TX, US High power regulator: 4 A max current While shunting, a yellow LED is lit. If the fuse blows, a red LED will light, but cell will soon be toast, so a human has to watch the LEDs at all times Fixed 3.67 V knee voltage, 3.7 V max voltage Not ideal for LiFePO4 cells: the shunt voltage is a bit too high Won't work with Thundersky cells: the shunt voltage is too low Won't allow LiPo and cobalt lithium cells charge fully: the shunt voltage is too low Between $ 40 to $ 60 each, depending on quantity

, by LL Labs (no website), sold by Anida in Dallas, TX, US

Notes

Company: Trade names are the property of their respective owners. A few other companies are getting ready to offer Li-Ion BMSs, but are not yet ready to be listed here (for example, Evie Systems). Picture:

• Click to see the complete picture (if available)

Topology (more info):

• BMS: does not include a switch to cut off the battery current

• Protector: includes a switch to cut off the battery current

• Centralized ("spaghetti"): single BMS controller with n+1 wires going to n cells

• Centralized with slaves: single BMS controller connected to a few slave boards, each with n+1 wires going to n cells

• Modular: single BMS controller with n+1 wires going to n cells; expanded by adding more, identical BMS controllers

• Distributed: small board mounted on each cell; BMS controller connected just to the 2 cells at either end of a battery

Number of cells: this is the acceptable range in the number of cells in series. The number of cells in parallel does not matter.

Cell shape:

• Small cylindrical: cylindrical cells to be welded, such as the 18650 or the 26650 sizes

• Large cylindrical: cylindrical cells with screw terminations at either end

• Prismatic: boxy cells with screw terminations on top, such as Thundersky

• Pouch: soft bags with tabs on one end, such as Kokam

• Any: there are no electronics on the cells, so the BMS works with all the above, using wires

Balance: The BMS is able to remove energy just from the most charged cells, to allow the other cells to reach the same level of charge. A balanced pack will have the maximum possible capacity. This is not as important for Hybrid Electric Vehicles.

Temperature: The BMS is able to measure and report individual cells' temperature. (The 'more info' tells you if the temperature measurement is not for every cell.)

Current sense: The BMS includes a current sensor or at least an input for a current sensor, to measure battery current. This enables the BMS to react to excessive current, and to calculate the SOS or DOD.

"Fuel gauge": a.k.a.: "Gas Gauge". The BMS calculates the SOC (State Of Charge) or DOD (Depth Of Discharge), by integrating the battery current. Devices that simply use the voltage to estimate SOC are not included here.

Communications: In general, the BMS must communicate with the rest of the system, to report the status of the pack, and be able to limit charging and discharging of the pack, in order to protect it.

• Wire: separate wires are used, each with a single, specific function, such as to turn on the charger relay.

• CAN: CAN bus, common in vehicles and European industrial equipment.

• RS232: serial point-to-point communication, usually used only for initial set-up and testing, but some time also available for communication during operation.

Fan: The BMS is able to control or drive a cooling system

Contactors: The BMS is able to control or drive a set of contactors between the battery pack and the load, including a precharge relay. Many motor controllers already have this function built in, so BMS controller that includes this function is not required.

Display: Either the BMS includes a SOC display, or the company sells a display that is compatible with the BMS.

Case: Whether the BMS controller is enclosed (metal or plastic case), or it is an open PCB assembly. Unless otherwise noted, any cell-mounted boards are assumed to be open PCB assemblies.

Price: from manufacturers' websites or discussion with them or their clients. Conversions into US $ based on rates effective at the time of writing. Unless otherwise noted, prices are for small quantities.

Custom BMSs

Companies that offer custom BMS designs:

DIY BMSs

Some open source, DIY BMS projects:

Cell manufacturer BMSs

BMSs from cell manufacturers, only sold together with their cells. Therefore, these BMS are not considered to be commercially available. They are presented here only for reference

To see additional information, hover your cursor over the icons.

Cell company

(1) BMS company

(1) Picture Model Topology

(3) Function No of cells

(4) Temper.

(7) Curr.

sense

(8) "Fuel

gauge"

(9) Comm.

(10) Fan

drive

(11) Contac.

drive

(12) Displ.

(13) Case

(14) Price Elite Power EPS - Distributed Digital balancer 200 ✓ ✓ ✓ Wire - - ✓ Plastic $370 / 16 cells

$470 / 24 cells

$1425 / 100 cells

Thundersky Ningbo Yangming

(no link: attack website) BMS40 Wired,

Master/slave Digital monitor 10,20,

30...100 ✓

✓ ✓ ? ? Incl.

Metal Valence Valence U-BMS Modular Digital balancer 4~768 each

✓ ✓ ✓ CAN - ✓ - Plastic Cell company

(1) BMS company

(1) Picture Model Topology

(3) Function No of cells

(4) Temper.

(7) Curr.

sense

(8) "Fuel

gauge"

(9) Comm.

(10) Fan

drive

(11) Contac.

drive

(12) Displ.

(13) Case

(14) Price

Also.

Other

The following are not BMSs, but perform related functions.