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12V 40A, 100A or 200A Smart Simple BMS
For 4 Lithium LiFePO4 Battery Packs in Series (4S)
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12V 40A, 100A or 200A Smart Simple BMS<br>For 4 Lithium LiFePO4 Battery Packs in Series (4S)
CAN Communication - 12V 4S Smart Simple BMS (Battery Management System)
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12V 40A, 100A, or 200A

Smart Simple BMS (Battery Management System)

with Bluetooth and Battery Temperature Sensor

For 4 Lithium LiFePO4 Battery Packs in Series (4S)

BMS Fundamentals Explained

Instructions for Paralleling Strings of Batteries

CAN Feature is NOT in USA stock. Delivery in 4 weeks.

Price with Options:

(Discounts, if applicable, will show in the "Shopping Pallet")

Notice: The prices shown are for merchandise and do not include shipping. Shipping will be billed separately.

Prices shown may be changed without notice.

12V 40A, 100A, or 200A 4S Smart Simple BMS (Battery Management System)
Constant Discharge Current Needed?
Bluetooth Module?
LCD Touch Screen Display?
Fan (for 100A or 200A)?
Delivery Date Needed? Enter it here:

Special Instructions? Enter them here:



  • UART: UART is Universal Asynchronous Receiver/Transmitter. It transforms the data to be transmitted between serial communication and parallel communication. As a chip to convert parallel input signals into serial output signals, UART is usually integrated into other communication interfaces.
  • RS485: Please choose the model RS485. RS-485 adopts balanced transmission and differential reception, so it can suppress common mode interference.
  • Bluetooth module: if you need this function, please choose the Bluetooth module. If you do NOT buy it, we will NOT send it to you.


Constant Discharge Current: 40A, 100A, or 200A

Over-discharge Current Protection: 120A, 300A, or 600A

Charge Voltage: 3.65V

Charge Current: 20A, 50A, or 100A

Over Charge Voltage: 3.75V

Over Charge Voltage Protection Delay: 1S

Over Charge Voltage Release: 3.55V

Power Balance Voltage: 3.5V

Balance Release Volt: 3.5V

Balance Current: 30mA (40A) or 35mA (100A or 200A

Over Discharge Detection Voltage: 2.2V

Over Discharge Detection Delay: 1S

Over Discharge Voltage Release: 2.7V

Over Current Detect Delay: 1MS

Over Current Protection Release: Off-load

Short Circuit Protection: External Load Short Circuit

Short Circuit Detection Delay: 250uS (40A) or 960uS (100A or 200A)

Short Circuit Detection Release: Disconnect Load (40A) or Off-load (100A or 200A)

Charge Temperature Protection: 32F (<0C) (Can be customized)

Discharge Temperature Protection: 158F (>70C) (Can be customized)

Main Circuit Resistor: <20 milliohms

Self-consumption Working Current: <100uA (40A) or 500uA (100A or 200A)

Self-consumption Sleepy Current (When battery is over-discharged): <20uA

Working Temperature Range: -4~158F (-20~70C)

Storage Temperature Range: -40~176F (-40~80C)

Accessories Sold Separately:


USB to UART Cable

USB to RS485 Cable

Bluetooth Module

Power Indicator

BMS LCD Control Screen

Wiring Instructions:


First, Preparation before installation


Make sure the batteries are of a good consistency, the voltage difference is no more than 0.05V, the inner resistance is no more than 5 milliohms, and the capacity difference is lower than 30mAh. Connect the batteries in parallel first and then in series. The better the battery consistency is, the higher the performance of the BMS.


Second, Wiring instructions


Attention: Please use our wires for our Simple BMS. Don’t use other factories’ wires because they don’t match up with our BMS.


Step 1, B-(blue thick wire): Connect to battery pack total negative pole –


Step 2, Disconnect the wires for batteries from the BMS side.


Step 3, Connect the wires to batteries. Start from the thick black wire to total negative pole (B1-), then connect the 2nd red thin wire to the 1st battery positive pole (B1+) B2+, B3+, B4+ … till the last red thick wire.


Step 4, When you are finished connecting all the wires to each battery, don’t plug into the BMS directly. We suggest you use a multimeter to measure the voltage of two adjacent metal terminals (You can see the white connector with silver metal pins on the BMS). If the voltage is 3.0~4.2V (LiNCM), 2.0~3.6V (LiFePO4), 1.5~2.75V (LTO), then the wiring is correct.


Step 5, Ensure the wires are connected to the batteries correctly and the voltage is normal. Then you can plug the wires into the BMS.


Step 6, P-: Connect P-(black thick wire) to load – and charger –

(if you ordered “common port”).


Charger+ connect to C-(yellow wire) load+ connect to P-(black thick wire)

(if you ordered “separate port”).


Step 7, charger+ and load+ connect to battery+. Please use thick wire.


Third, Measure the total voltage of the pack and the output voltage of the BMS. If the voltage is the same, it means the wiring is correct. You can use the BMS now. Otherwise please check the wiring again according to the tips above.

Frequently Asked Questions about the BMS/PCB:

1, Which current PCB should I use?

Take a 13S 48V pack as an example: Which PCB you should use depends on the power of your motor or the current limitation of your controller. Below 350W, you can use 16A. Below 500W, you can use 18A, Below 800W, you can use 35A, Below 1KW, you can use 60A. Above 1200W, the same. If you are not sure, please contact us.

2, Can I use a bigger size of PCB than is indicated?

Suppose you need 60A PCB but you chose 80A, that will work.

80A allows for a higher current. A bit higher price is the only drawback.

But if you choose 50A, it will be too small. So you can use a higher spec but not a lower one than it should be.

3, What kind of charger should I choose?

A Lithium Battery must be charged by a Lithium Battery Charger. You can’t charge it with a lead acid battery charger because the lead acid battery charger might damage the MOS pipe of the PCB.

4, if I have a PCB, do I need any balancers?

Yes if you add QNBBM balancers, that will be perfect.

The Main function of the PCB is to prevent batteries from over-charging over-discharging, over-heating etc.

With balancers added, the batteries lifespan will be longer and the capacity will get fully used.

5, How do I judge if my PCB is broken or not?

If you’d like to judge if the PCB is fine or not, please use a multi-meter and see if the voltage of each cell is close to one other or not. When the voltage difference is 1V, the battery will have this kind of performance: the driving distance will be short, it will be cut off when started, the charging time will be very short. Under such a situation, a battery is defective. When the PCB is broken, the battery can’t be discharged. When you measure the battery voltage, it will be normal.




There are 2 ways to get an exact quote for the base shipping for your 12V 40A, 100A, or 200A 4S Smart Simple BMS (Battery Management System) order.

1.  Contact us at (801) 566-5678 9am-5pm Monday-Friday or email [email protected] or go through our Contact Us page




2. Place your order by clicking in the shopping pallet “Proceed To Checkout”

a. Enter your information so we can get you a shipping quote

b. Select the “Shipping Method” of preference

c. Confirm the “Choose one payment method” has “Shipping Quote Request” selected

d. Click the “Check Out” button

e. You’ll receive a confirmation email of your request, as will we


We’ll research the exact shipping cost and send you an invoice to your PayPal or email or you can add it to your pallet in $1 Shipping Increments for your 12V 40A, 100A, or 200A 4S Smart Simple BMS (Battery Management System) order.



Quantity discounts show in the “Shopping Pallet”.

We love to meet or beat any competitor’s price!

Contact us with questions

9am-5pm Monday-Friday (mountain time)

(801) 566-5678

or email

[email protected]

or through our Contact Us page

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