Best BMS for LiFePO4

When looking for the best BMS for LiFePO4, you might get overwhelmed with different choices. This article will make you pick the right one.

There are a few parameters in which you would be interested in. These are:

  • Current
  • Voltage
  • Amount of cells
  • Balancing current
  • Place of manufacture
  • Low temp disconnect
  • App connectivity
  • RS485

From here, we will list the most used BMS’es for LiFePO4 batteries.

Most Used BMS for LiFePO4 Battery Cells

1. JK smart BMS

The JK or JIKONG active balancer BMS is a great choice for 48V systems. The app layout is easy to navigate with many options. It comes with three temperature sensors for high and low-temperature cutoff. The BMS uses active balancing.

  • Current: 100 to 200A
  • Voltage: 48VDC
  • Amount of cells: 4S to 24S
  • Balancing current: 0.6 to 2A
  • Place of manufacture: China
  • Low temp disconnect: Yes
  • App connectivity: Yes
  • RS485: Yes

2. JBD or Overkill Solar

This BMS is getting more popular amongst DIY battery builders. And for a good reason. it features all the necessary elements needed in a BMS.

The BMS is made in China and is also sold by Overkill Solar. Overkill Solar claims to do an additional calibration before shipping it to customers.

  • Current: 6A to 300A
  • Voltage: 12V to 96VDC
  • Amount of cells: 1S to 30S
  • Balancing current: 20-40mA
  • Place of manufacture: China
  • Low temp disconnect: Yes
  • App connectivity: Yes, XiaoXiang
  • RS485: Yes

The balancing current is relatively low, so an initial top balance and having a passive balancer is advised. The app is very easy to navigate and adjust parameters. I recommend this BMS as a reliable but still a budget option.

3. DALY

Daly has been a popular choice since the beginning. A lot of people have chosen this brand because of the many guides which you can find online. It has a vast range of options for you to choose from. It has smart options and standard options. The smart option work with Bluetooth and an app. The standard option is a plug-and-play version.

  • Current: 10A to 500A
  • Voltage: 12V to 120VDC
  • Amount of cells: 3S to 32S
  • Balancing current: 30mA
  • Place of manufacture: China
  • Low temp disconnect: NO
  • App connectivity: Smart version, yes. Standard version, no
  • RS485: Yes

https://www.evlithium.com/hot-lithium-battery/daly-bms.html

An important thing to mention with Daly is that while the discharge current is 100A, the charge current is only 50A. The balancing current is rather low at 30mA. Below you can see the spec sheets. It also has no low-temperature disconnect. A real turn-off when you live in a cold climate.

4. REC BMS

REC is a Slovenian company who makes a reliable BMS. The BMS can be paired with a shunt and is Compatible with SMA sunny island. The standard REC Q BMS can be used up to 16S, and with the master unit, you can connect 240 cells in series. It also has a relay and digital outputs. The current doesn’t pass through this BMS like the DALY or JBD BMS.

  • Current: Doesn’t go through the BMS
  • Voltage: 13V to 68VDC
  • Amount of cells: 5S to 16S
  • Balancing current: 2A
  • Place of manufacture: Slovenia
  • Low temp disconnect: Yes
  • App connectivity: Connected to the web for remote access
  • RS485: Yes

Their customer support is good and compatible with Victron (cerbo GX), so you can have the battery shown on their display.

This BMS can be used with an alternator because its output can turn off a relay.

5. Batrium BMS

CellMate-K9 is the most recent version of their product line. The Batrium BMS is ideal for DIY powerwalls. With it’s many available expansions and great graphical interface, this BMS is a great option. The current doesn’t pass through this BMS like the DALY or JBD BMS.

  • Current: Doesn’t go through the BMS
  • Voltage: 12V to 48VDC
  • Amount of cells: 3S to 16S
  • Balancing current: 500mA
  • Place of manufacture: Australia
  • Low temp disconnect: Yes
  • App connectivity: Connected to the web for remote access or app
  • RS485: Yes

Data logging for over 10 years with a built in clock. Additional input and outputs are available with expansion boards. You can extend the BMS if you want to add more cells to the system later.

WatchMon-CORE kit for CellMate-K9

6. QUCC

The QUCC is a BMS that uses a relay instead of MOSFETs to break the circuit. This results in the cost being lower, but that doesn’t make it more reliable.

If you have a capacitor in your system from an inverter and the relay closes, the arc between the two contacts can cause both contacts to melt. This can prevent your relay from opening again.

Orion BMS

Coming soon

Heltec BMS

Coming soon

BMS Buying Guide

How Do I Choose a BMS for LiFePO4?

Do you want to adjust the parameters in your BMS? If so, then choose a smart BMS. Most of the BMS’es you can find are smart.

Do you need a low-temperature cutoff? Having that kind of protection might be necessary if you live in a climate where it gets cold.

Is your battery pack top balanced? A BMS with a higher balancing current will be the best choice if it’s not top-balanced.

Do you value products made outside of China? If so, there are many options, but you will pay a higher price for them.

FAQ

Do LiFePO4 batteries need a BMS?

If you are building a DIY battery, you should add a BMS. They can work without, but the cell voltages will drift away from each other over time. One cell will lower the whole battery voltage and will be damaged. That’s why a BMS with a balancer is needed.

If you buy a ready-made battery, the BMS will be included.

What is the difference between smart and dumb BMS?

A smart BMS connects to an app through Bluetooth, wifi, RS485, or a CAN connection. You can change the settings in the graphical interface. A standard or ‘dumb’ BMS is plug and play. The settings cannot be changed.

What is the difference between a switch BMS and relay BMS?

A switch BMS uses MOSFETs to turn off the current. A relay BMS turns off the current with a relay. It’s worth noting that a relay is not always made to interrupt current as a breaker can. So the relay contacts can ‘stick’ to each other.

What is the difference between active and passive balancing?

Passive balancing will remove or add capacity from a particular cell and dissipate it as heat. Active balancing takes the excess from one cell and delivers it to a cell with a lower voltage. Active balancing has fewer losses -and is thus more efficient.

What size BMS should I use?

As mentioned in my other article, you should not go over 100Amps in your system. If you do, you need to increase the voltage of your system. I still don’t understand why people would buy a 300A 12V BMS. It’s a waste of wiring costs and a safety hazard. Below are my recommended inverter sizes for a particular system voltage:

  • 12V: inverter below 1,200W
  • 24V: inverter below 2,400W
  • 48V: inverter from 2,000W to 5,000W

Using these guidelines will not only save you on wiring costs, but it will also save you money on a BMS and a charge controller.

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